My Rain Gauge is Busted podcast series

Here at My Rain Gauge is Busted we talk about all things climate and farming. We explore stories from farmers, researchers and innovative folks, about:

  • our weather
  • the seasons
  • the climate
  • what’s normal and what isn’t.

We also explore the great work underway that is setting us up well for the future.

Subscribe to My Rain Gauge is Busted

You can subscribe and listen to My Rain Gauge is Busted wherever you get your podcasts:

Your feedback is important to us so make sure to rate and review our episodes and share with your friends and family.

Season 2

Episode 6: How to be certain when the outcome is uncertain

Jemma Pearl:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Jemma Pearl, and here we talk about all things climate and farming.

This episode is part two of our discussion with Think Agri’s Kate Burke. In part one Dale Grey, Graeme Anderson and I asked Kate about seasonal risk decision making and what her tips are from her more than 30 year experience.

In this episode we talk about making decisions with uncertainty and the different business structures that can assist with spreading risk.

Kate Burke:

Graeme summed up before it's humans making decisions. And one of the reasons I wrote the book was because I felt the human component of advice wasn't getting through in the technical publications in industry. And the human component of advice probably wasn't even getting a lot of airplay at seminars and things. So I wanted to join that link up that the impact that uncertainty has on the way you've thinking on your neuroscience, the impact that trauma has, lets face it floods, droughts their traumatic conditions. So then that affects your ability to make good decisions. And it also explains why I probably spent the first 15 years of my career and on the first five years of my consulting career, getting frustrated that people couldn't take the emotion out and just follow my logic.

Kate Burke:

And we hear that from advisors all the time and from extension officers and from scientists, and logic's fine, but we've got this emotional part of the brain that keeps hijacking the logical part. And weather makes us emotional. They've been writing poems about the emotion of weather for 150 years. But the really cool thing is the science of the brain says that if you actually put data in front of you, it helps your brain access the logical side of your brain. And it actually can calm down the emotional side of the brain. So I remember reading an article by this guy called Travis Bradbury about uncertainty and this research that he was quoting. And that's when it made me think. That's why it's worth, people need to understand this, that why it's good for them to not just rely on gut feel and intuition, and that gut feeling intuition are fantastic when your brain's tracking along well. But if you are stressed or in a state of high emotion, your intuition can sometimes trick you.

Graeme Anderson:

Kate you've understood and you helped lots of businesses manage the dealing with seasonal variability and make the most of good years and limiting risks in the tricky years. And you also across a bit of, what's sort of lining up for us in terms of climate change. So just wondering, have you got any thoughts about...is there anything different farms should be trying to set up for apart from just trying to do good management of seasonal variability? If they're trying to set up their farm for the next 20 years of what we understand might come with climate change, any thoughts?

Kate Burke:

Yeah, look a really good question. And again, I think it's goes back to, I suppose, the three A's of awareness, acceptance, and action or you might even call it four A's awareness, acceptance, agreeance and action. And what I mean by that is, it's your farm so it's your responsibility to make sure you are aware of the possibilities of what could happen in the next 20 years in terms of your rainfall, variability and your temperature exposure. So again, using the data analogues that are being produced by the people like yourselves and CSIRO and some of the universities it's useful to know that could look like Deniliquin in a few years time and there in further down the track, it could look like Griffith. And so that gets me thinking, well, what do I need to do on my 300 acre block if I'm going to have a climate like Deni.

Kate Burke:

So that's the first thing is just be aware of the possibilities and accept them. Someone said the other day that unfounded optimism is not leadership. It's actually denial. It was a lady called Susan David. And I think we've seen a lot of unfounded optimism in other aspects of our life and leaders in recent times. So that's the first bit, awareness and then acceptance. Now, we've got to get on with the job. So we don't really know what that job is yet, but there are a couple of the things. The first thing I think is to make sure you've got a really highly operational and profitable business. And then what the highly operational and profitable businesses look like in the areas that you might be farming in? So Wimmera farmers are really starting to farm like Mallee farmers anyway, nowadays, particularly in when they see dry years coming.

Kate Burke:

So that's an example. I think the tricky bit is this agreeance bit before you decide what actions you're going to take, if there's multiple business partners in your business and your advisors, and for some people, climate change is still a political beast and some people might not quite be there yet, and there might be a generational gap. So the 30 year old in the business learnt about it at uni, the 20 year old learn about it at school, the 60 year old might still see that's something associated with a political flavor that they're not that keen on. So getting through all that, to the agreeance bit, to make meaningful change for a business, that's part of it. And then there's the action bit. So there're the actions in individual years and there're the actions in the future. We're seeing it already. Some people are shifting or buying land in different places or changing the way their enterprise looks. But I think if we follow that sort of... I guess, just think about awareness, acceptance, agreeance, and action. We can get through anything really.

Graeme Anderson:

Great observations and comment there because the world's still going to need food. And when we look in different climates, we see people farming successfully. So it's not actually the climate that determines whether someone's a great time of it or not. It's about these other things. But, it will change over the time. It's just sort of learning as we go. Surround yourself with good people. And like I said, I think we were talking on one of the other podcasts Jemma, just even the things that are in our favour, such as just improved forecasts and things like. Now on our phones we've got a pretty reasonable seven day forecast that farmers 30 years ago, would've just dreamt of some technology that had the week's weather in your pocket. Amazing.

Kate Burke:

We've got so many good tools around and I think it's silly not to use them and use them well. Using them well, doesn't mean looking up every 10 day forecast until you find the one you want. Using them well means making sure all your paddock records are up to date, for example, and that you've actually done an analysis compared to your potential yield that you understand that you've got some soil moisture probes and what's going on and you're linked into the weather stations that are around there, all the things we can do really well. And you're dead right about wherever you farm people can make money. It's just about understanding the system required for that climate and doing it well. And I think one other aspect relates back to before talking about intuition and using information, a trap for young players is to look at the older, whether it's older advisors or older farmers who have got 30 or 40 seasons under the belt. And they're making lots of intuitive decisions in their head and they're actually pretty good at it because they've got a filing cabinet of 40 years.

Kate Burke:
If you're a young agronomist, who's got a filing cabinet of two years, it's actually really risky for you to be making all those decisions in your head. And if you're a young farmer with a filing cabinet of two years, it's also really risky to be making all those decisions in your head without any data, because you don't have that internal intuition that comes out with positive outcomes. A lot of it comes from experience. So I think it's really important to just for younger listeners to understand that it's worth the discipline and making the effort to use good tools that are available to us now.

Jemma Pearl:

As Kate mentions having the data to help make decisions is really important. We asked how important was having soil test information and why have we seen a drop off in their use.

Kate Burke:

A very good question and I'm being quiet because I'm trying to add up the years that I have been work. Are we in 22? So 32 years and I still don't have the answer to this. Human nature, it's discipline. It's about discipline. Ultimately it's a choice of an individual to take on that practice and unfortunately, in advisor land and agronomy land, there's a big shift away from soil testing. So when the top crop and maximum economic yield may check programs was strong when pivot was doing soil testing and wasn't charging for it, charging for the sampling but not the sorry charging for the analysis, but not the sampling.

Kate Burke:

It used to be a lot more done. And human nature is if you don't want to do something, you can rationalize why you shouldn't do it. So the one time we got a bad result, that has then convinced us that we shouldn't do it for the next 30 years. And unfortunately... So there was a lot of misinformation out there. I think I'm not sure whether soil testing has picked up in recent years, but I am finding... it seems to me that people have got the nitrogen message in the last few years and have got better at it. I hope that with one good thing about higher input costs is it does give people the motivation to do more soil sampling and soil testing.

Kate Burke:

Yeah. Look and it's not perfect. But I think the famous economist, John Kane said that it's better to get the whole roughly right than part of it precisely wrong. And still the soil testing results I've looked over the years, just the variability within a farm you'd have the same paddock history, but there could be a 100 kilos per hectare of urea equivalent different between one paddock and another. So you think about that in today's prices, like it's huge. So we've got an allocation of capital that needs to go into our nutrition. Let's make sure it gets in the right spots rather than making broad assumptions, I reckon.

Graeme Anderson:

We always love talking about agronomy and weather, but in your observation, and in your book dealing with a lot of different farms, what are the key things you think that make a successful farm business or farm family business? Because often we can spend most of our time talking about agronomy and what needs spraying and what needs doing and all that operational stuff and technical stuff, but just in your observation, what are the things that stand out for those businesses that impress you in terms of how they go about it all?

Kate Burke:

Yeah. Really good question. And I guess I'll answer it on the basis of not just observation, but a lot of research and collation of other people's research, both qualitative and quantitative. And it comes down to three themes really. And that's those three themes evolve around the title of the book, crops, people, money. And the whole of the system. So the business is that really impress me, see the farm as a whole, whether they know they're doing that or not, they do that. They are the type of person who is good at relationships and that helps them get things done. They're really good at logistics. So their timing's good. Their management's good, their organization is good.

Kate Burke:

They're technically strong. So they understand why they need to do what they need to do and when. And in terms of business structures and finance structures, their level of capital expenditure and their overheads is commensurate to the size of the business. So they're not overly geared with machinery on a thousand acres, for example, but they're not under geared on 5000 acres and they're losing timing. So they get that balance right in terms of fixed costs. And probably the most critical factor is that they recognize that it's their farm and that they're the ones responsible for the actions on that farm. So they're not the type that changes agronomists every four years or bankers every five years.

Kate Burke:

They own their decisions and they're good to work with. They get advice. They've got that capacity basically to work through the decisions and work as a team. That's it in a nutshell really. Crops, people, money and you, the art of excellent farming.

Dale Grey:

So I had one that I wanted to explore, which was the concept of a business or a farming system being what's termed anti fragile. So when something happened, it doesn't break. It's actually robust sort of system and it can cope with all sorts of things. And historically we've seen mixed farms quite capable of that, but more so in... I think there's a lot of continuous croppers who believe that their system can. Do you have any sort of personal thoughts about either of those different ways of farming and what might be better, or is it really a case that some farmers are good at it and some aren't?

Kate Burke:

Getting into dangerous territory there. So anti fragility really good term. Robustness, a very good term and thanks for the reminder, because one of the characteristics of the farms that impress me is they do have that robusticity built into their business. So they can handle production shocks or financial shocks or personal shocks. Basically the higher the cost structure of running a business, the bigger the buffer you need sitting behind you to be able to manage that risk if things don't go well. And in terms of mixed farming versus crop only farming, I think it depends on what else is going on in the back end of the business.

Kate Burke:

And it also depends on where you are farming. So there's been some really good research done over the years, both modeling and real data that indicates that last 10% of crop land, it really escalates the input costs. And depending on where you're farming that can be problematic. So there's a reason why in certain areas, it makes more sense not to crop every paddock every year. And that's just down to the principle of diminishing returns that your first dollar gives you more value you than the last dollar you spend on something. So I do worry sometimes on some businesses that are persisting with cropping every paddock every year. I think you don't necessarily have to have livestock in your system to have an anti fragile farm. You had plenty of examples that just manage that by lowering their crop intensity, which then lowers the cost base. I've seen fantastic livestock and cropping mixed enterprises and I've observed some not so good ones.

Kate Burke:

So again, that comes down to this whole of the farm effect that statistically the difference between performance of farms in an area, the biggest variable is all the characteristics that make up the individual farm rather than it... So in other words, it's not what they do, it's how they do it.

Jemma Pearl:

Decision making is not a skill we are necessarily born with, Kate explains how important it is to be disciplined in seeking information and considering the consequences, even if the outcomes are unsavoury.

Kate Burke:

It's really interesting. And having the ability to see forward and see possibilities clearly is actually not that common a trait. So you sort have to teach yourself to do it. If you do something like the Clifton and strengths finder, there's one characteristic called possibilities. And in the type of personality that a lot of farmers are, it's not a common strength. So they're more likely to see what's there right now in front of them. A lot of the guys and girls that have that natural ability to think three months ahead or four months ahead and think through the options, not only the logistics? It's a really good trait to have. It takes a while to get through that. It's the human nature. And it's a survival mechanism not to think about stuff that can hurt you. Our brains are still working on the same evolution thousands and thousands of years. So although we have all the data now that we can look at all these different possibilities. Our brains are still saying to us, oh frost that's bad. So we don't want to go down there.

Kate Burke:

If we go over and touch that tiger it might eat my hand off. So it takes discipline. It takes courage and discipline to go down that path. And I think we saw that this year where the frost... I think we're getting good at that now in terms of thinking about rainfall and various potential yields. I think we've still got a way to go when it comes to frost, particularly when you can see the potential in front of you. And I even fell into this track myself a bit this year, trying to convince myself that well, the temperatures really need to be below zero, not just below two. And then once you actually get out there and start looking you think, oh dear. But there was a lot of... There are still are getting nasty surprises at harvest. And that's because we are not thoroughly investigating and in some sort of a logical methodical way what's happening out in the paddock in terms of frost damage.

Dale Grey:

Silence in the bin, Kate. It is not the time you should be first knowing you've got a problem.

Kate Burke:
No, it's not but it's understandable. Its human nature. So I think that's where... Again, it's really... It's the advisors. I do see it as one of the advisors' role is to sort of nudge people towards thinking about the things they don't want to think about and let them know. Look, we are seeing a lot of frost in the area. How about we catch up and go and have a look at the frog pad because every year there's been frost around, that's been in your worst paddock, or if you don't know the farm that well, it might be, hey Jan, I'm seeing a lot of frost around other paddocks where you all had difficulties with frost in the past. Would you like me to go and have a look or let's get your yield maps out from the last time you had a frosty year or things like that. It's just inviting that conversation. And ultimately, it's up to the individual to... It's up to the individual business owner and manager to take that next step and start to be more methodical about it.

Dale Grey:

I think Kate, if we were honest, not every agronomist would like doing that job either.

Kate Burke:

It's horrible.

Dale Grey:

They're thinking of the potential repercussions of finding something that's... you are right. There's literally no joy in doing that, but ultimately if you're helping people make better decisions that's good.

Kate Burke:

Yeah. Look, I found myself in that.... I don't do traditional agronomy anymore, but I did find myself out in paddocks and got a real surprise in a certain district late last year. And I was a bit shocked as to what I saw. And there was a couple of crops that were really badly impacted by frost. So I did ring around some friends and some other clients and just sort of nudged them back out to have another look. And we found some good stuff and some not so good stuff. And luckily, because we had such a soft finish and a bit more rain there was some enormous compensation in lentils in some areas. I just couldn't not do it, even though it wasn't necessarily my role in that situation.

Jemma Pearl:

We greatly appreciate Kate joining us on not one, but two episodes. Dale, Graeme and I definitely enjoyed spending time and learning from Kate’s years of experience.

We explore the concepts mentioned in this episode further in an up coming episode with Cam Nicholson.

In the shownotes you can find more information and links to decision making.

You can also get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria and The Tribe.

Episode 5: The art of seasonal risk decision making

Jemma Pearl:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Jemma Pearl, and here we talk about all things climate and farming.

In this episode Agriculture Victoria’s, Dale Grey, Graeme Anderson and I, talk to Think Agri’s, Kate Burke. We had such a great time talking to Kate, that we have had to split the interview out over two episodes.

In this episode we talk about seasonal risk decision making and some of Kate’s tips from her many years of experience.

We asked Kate to recall how seasonal risk information has changed over this time.

Kate Burke:

I reckon where one of the good things is that we've got a lot more information at our fingertips compared to when I first started working in AG. My first year of working was 1990, which I think from memory was an El Nino year, but I didn't ever know what an El Nino was then. And I do recall canola flowering just outside of Dooen in about June, July. So we're a lot more informed. I guess what we've noticed though, is... when I go to 2002, which was the first real, proper drought that I experienced in my career. And I'd been in the career 12 years by then. We just assumed that the '83 phenomena, and that you get a great year after a bad year.

Kate Burke:

And in 2003 was okay for some, not great for others, but then we started to get all these other horrible years happening. And, I recall in '97, is actually going to a seminar that Zvi Hochman and some of the other CSIRO guys, and they sort of put up this model where they were basically saying that we were about to enter a 10 year cycle of ordinariness. And I remember thinking at the time, oh, what a load of something. And because I didn't know anything, but you think you know everything when you're in your mid twenties and they are right. So I think...but we still have this mentality in our head that dry years shouldn't happen very often. So even though we went through that millennial drought and learned how to manage risk and particularly in the Mallee in Victoria and in Western Victoria and towards the end of the millennial drought through work.

Kate Burke:

Through the work that you guys did with your climate dogs and with the break, we got to understand about variability and why it had happens and the penny started to drop. But then, when it happens again saying 2015 or 2017, 2018, 2019, all of a sudden we are back in disaster mentality.

Kate Burke:

And it's not pleasant, no one wants to live through those circumstances, but we just have to get used to it and manage it, I think. Because they're not happening once or twice the generation now. They're happening a few times a decade. And, until we accept that and then start to work with it. And I think it's really important for advisors. Because it is not our job to go out in sympathy and lose our ability to make rational decisions during tough times. It's our job to do whatever we have to do and to be that calm voice of reason and use whatever tools we've got.

Graeme Anderson:

I was just wondering from your point of view, how important is seasonal variability that you've seen on the impact of the farm businesses you work with? And what are some tips for the... How to do you set up a farm businesses try and roll with that variability? And, make the most of the good years and limit damage in the bad, especially when you don't know what's going to happen.

Kate Burke:

Really good question. And I think it's a matter of... Obviously it's vital to get your head around this and understand where you fit in the scheme of variability. It was a real eye opener for me when I started seeing people present just simple rainfall variability and using standard deviation or coefficient variation of annual rainfall. To look at that variability and just see the differences there are around the cropping regions in both Victoria and in Southern Australia in general. And once you understand that you're in Mildura and that one year your rainfall could be twice as much as it was the previous year. And that's quite normal for your region. It really changes how you think about things.

Kate Burke:

Similarly, it also helps you understand that when the good years are eventuating, you've got to take that opportunity. And in those more variable and less pleasant years, it's really a matter of bating down the hatches or not bating down the hatches, but basically minimizing losses in the extreme poor years. I think one thing we make a bit of a mistake when we try to level out our business and minimize the variability within the business, because by doing that, we could actually be foregoing opportunity. And there's a difference between variability and volatility and the risk that comes with both of those, I think.

Graeme Anderson:

Yes, Kate. When I guess it's interesting when we're in a pre the Autumn break and planning out the season, of course, we're always really hopeful that each year is going to be a ripper. So what steps do you used to try and set up? How do you set up to be ready to make the most of things? But what sort scenarios, or what do you use when you helping set up a business for how to play it the year out as it unfolds?

Kate Burke:

So considering we only have rippers say two in 10 years, I sort of don't start with that. What I like to do though, is look at our base level of where we're at now. So, and think about, well, if we're, we're in the game of cropping, we're basic dry land cropping, we are farming soil moisture. So how full is the bucket at the beginning of the year is the first place I look at. And then I think, well what are the climate models telling me about what might happen in the next three months? So let's assume that we're coming out of a dry spell, for example, but there's a...all the models are suggesting that it's going to be above average for the next three months. And let's use the current example what we're in a La Nina phase, depending where you are and where these summer storms sit.

Kate Burke:

Well, gives you a hint that you might end up with some subsoil moisture by sowing time. On the flip side of that you can have years... So what happens if that rain doesn't occur and what happens if you are in the area that missed out last year and you've got a really dry soil profile and you haven't been able to get any of these storms through. So you're probably going to have a below average soil moisture bank. And obviously you can measure that too. So I tend to start with where you're at, then into terms of projecting forward and what the possibilities are. That's where I use some of the tools that you and your colleagues have produced along with the tools that come out of the bureau and have a look at the form guides.

Kate Burke:

So have a look at those models from around the world and your summaries of them and see what they're saying about the next few months and whether they're saying the same thing or not. And if they're all suggesting the same thing, that's when I think, okay, that's interesting. Either we get excited or we get a bit concerned depending on whether it's a positive or a negative indicator. And if they're all over the shop, it's like oh, well, we just have to face every ball as it comes. If we were playing cricket, for example.

Kate Burke:

So do that. And in some years you can be... So 2015 was a classic where already talking high possibility of El Nino and IOD positive for that year. And so my alarms just go right off when I hear that. And if you've got 10 out of 12 or eight out of 10, whatever number of models you've got all saying the same thing and I get really nervous if it's a more benign type situation, I think you do need to be mindful and have a bet each way in terms of how we're setting up the season and what we're planning for.

Jemma Pearl:

A lot of people like using averages as their baseline for decision making, but is this wise?

Kate Burke:

So I suppose I stole this statement from Bill Malcolm from Melbourne university that averages are an artificial construct and averages work okay if there's not very big extremes. But because we are getting so many extremes now we're getting like the lowest on record one year then three years later we've got the highest on record and we've got a few in between.

Kate Burke:

And this variability doesn't look like it's going away. If we make an average out of that and plan for that average looks a bit meaningless. So I tend to take an average of the good years and average of the bad years and an average of the ones in between. That's basically that's how I do it and say, well, what does that mean for us? And then try and match those up with the climate indicators. And I found that really quite useful last year. Because instead of targeting average in terms of yield potential, we were leaning towards higher than average. And looking at the averages of other years where we'd had cool finishes, for example, because of a La Nina or IOD negative and factoring that in, even though it wasn't necessarily presenting in rainfall.

Dale Grey:

Kate, you're spot on. I do so many talks around Southeastern Australia and look at the historical rainfall. I ask people, do you put up the data and go? How many of those growing seasons are close to the average? And the answer for just about every location is about 10% that are close to the average, 60% of them are nowhere near it, like they're either grossly wet or grossly drier.

Dale Grey:

And well, that's right. So if you're banking on the thing that might happen one in three times, you're missing out on the other 66%. Yeah, it's-

Kate Burke:

I guess that's a real... I guess the practical implications of this is when we're making decisions on things like nitrogen, it's really concerning if we are sitting with someone and let's say the Wimmera average is 3.2 tonne to the hectare of wheat, could be even a bit more than that over the last few years. And we're sitting there and all our advice is based on 3.2 tons of the wheat to the hectare, and we're not taking into account what the climate's delivered us up until that date and what the possibilities are for the next four months. There's a lot of dollars involved in that shortcut.

Graeme Anderson:

And talk us through some of the difference, Kate, like just between in those last few years in that yield and the difference. If you're driving in the... Because when things are going right or when you're backing your judgment, because things are lining up that this could be one of those upside years. How does that translate out to differences in yield and the businesses like?

Kate Burke:

Yeah. First thing I'll say is it's not easy, because last year I was getting very nervous

Kate Burke:

In September and I was sweating on all those conversations I'd had on other podcasts and seminars and my own clients. So it isn't easy. I guess you're talking five and six ton in a medium rainfall area in those really favourable years, opposed to say the three ton that equates to an average. And then the flip side of that is if you look at just the IOD positive and El Nino years, so the fair dinkum drought years. Once you add frost into there, you are sort of looking anywhere between zero and two ton to the hectare. So just take last year for example, we've set up crops for three ton, leave two ton to the hectare of wheat behind at current wheat prices, that's anywhere between 600 and $800 a hectare left in the paddock.

Kate Burke:

Now, obviously we can't get all of that, but effectively that money pays for the putting the crop next year's crop in plus your overheads. I did some sums on this Graeme, sort of using I think it was 2017 as the year in the Wimmera based on one of the local accounting firms, benchmarking figures. And the amount of money left behind was extraordinary. It was basically, it was... I worked out something like for the Wimmera it was $80 million on a really simplistic way of working it out. You can read all about it in the book. So I suppose when we think about government grants and political support and all these things, there's a lot of value staying out in the field in good seasons.

Graeme Anderson:

I guess like you were alluding to earlier with perhaps increasing variability, it's sort of just upping the ante between which one of those years have we got in front of us and the importance of capturing those good years, which are then relying on decisions made by the human. So when there's plenty of extra moisture around, how do you capture it so that it converts across to the balance book? I guess and because it's always easier in hindsight, but it is fortune favours the brave.

Kate Burke:

Yeah. And I think that's right and it's easy. It's easy reflecting on if I just use the Wimmera again, sort of that central Wimmera, the Southern part of the central Wimmera ended up having another fantastic year, but you don't have to go too far north to miss that. And so knowing what's happening on your place and knowing what... Even though the climate indicators might be saying, well, we should be heading for this type of year, but if it's not running on your place, you need to be making decisions around that too. And so what I'm saying, if it looks like a duck and quacks like a duck, it's probably a duck.

Dale Grey:

Yeah. If you've only had decile two or three rainfall to date, there's not many years, Kate that suddenly flipped to eight. They're pretty rare.

Kate Burke:

Yeah, like some of them happen, but not often.

Dale Grey:

In 1993, everyone remembers that one.

Kate Burke:

That's true. We always remember the favorable. And I guess the flip side to that though, Dale is also this whole concept of what's in the bank before the season. So 2011, it didn't rain a lot in the season of 2011 but-

Kate Burke:

In crop was awful. We had incredible soil moisture and it was a real challenge for people to have that confidence after 10 years of horribleness and then bit traumatized by floods. It was a big challenge to encourage people to believe that there was the potential there. And I think we've got less excuses now with the monitoring tools that we've got and the more accessible information.

Dale Grey:

I think that year might have been a turnaround for a lot of people Kate because a lot of people saw what they were capable of growing with very little in season rainfall. And seeing is believing, as they say. So people that were stripping four and five ton crops in relatively low rainfall areas, but all based on store soil profile. Now they've remembered that. And they're more likely to be acting more favourably, I think in the future.

Kate Burke:

And the other real learning curve that year was we sort of had this attitude and I guess it comes from down south a bit of all there is excess water there. So we don't need to be so diligent on summer weed control. And but then we saw firsthand areas where you couldn't get the boom spray and they'd be full of pigweed and crassula and all these funny water weeds. And then you'd see the other half, the bit where we did eventually get some spraying done. Come back into those crops in August and you think, oh what's going on here? And that area that wasn't sprayed was so nitrogen deficient and probably had a bit of root disease. And obviously it had sucked up some moisture. That really got a lot of people over the line in terms of understanding the importance off season weed control, regardless of the rainfall. And even the 80 year old sheep breeder whose son's madly in love with cropping, all of a sudden stopped complaining about his sheep feed getting sprayed out.

Dale Grey:

Yeah. There were fabulous in paddock comparisons that season because that's right. There were parts of it missed and it was just chalk and cheese and that was their right until harvest as well.

Kate Burke:

Yeah, it was fascinating. Certainly something that always has stuck in my mind. And I guess it's one of those well... We never really knew the answer to that. And well, then we did.

Jemma Pearl:

That is where we will leave part one of our discussion with Kate. In the next episode we hear from Kate about her observations of some of the decisions people make when considering uncertainty.

In the shownotes you can find more information and links to seasonal risk decision making content.

You can also get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria and The Tribe.

Episode 4: Spinning around with the Southern Annular Mode

Jemma Pearl:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Jemma, and here we talk about all things climate and farming.

Jemma Pearl:

In this episode Agriculture Victoria seasonal risk agronomist, Dale Grey, and I talk to Bureau of Meteorology climate scientist, Andrew Marshall, about the Southern Annular Mode. Andrew has been with the Bureau for more than 12 year and spends the majority of his time looking at multi-week to seasonal forecasts and understanding the different influences on Australian weather and climate.

Jemma Pearl:

The Southern Annular Mode, or SAM for short. Is probably one of the lesser-known climate drivers, that has a significant effect on rainfall and temperature in southern Australia, both east and west.

Andrew Marshall:

The Southern Annular Mode is one of these things that we call climate drivers or modes of variability. One of these major influences on Australia's climate, there are several of them, they range from up in the tropics, the El Nino Southern Oscillation and the Madden-Julian Oscillation, Indian Ocean Dipole. And then around our part of the world there are high pressure blocking events, and then when you get down towards Antarctica, there's the Southern Annular Mode. So that's really the major mode of variability that affects us, which really is centred over Antarctica, but it makes its way here and affects our climate.

Jemma Pearl:

One of the interesting aspects of the Southern Annular Mode that is different from El Nino Southern Oscillation and the Indian Ocean Dipole, is that the Southern Annular Mode only affects the Southern Hemisphere. In the Northern Hemisphere, they have the Northern Annular Mode.

Andrew Marshall:

And actually my work started off looking at the Northern Annular Mode first, before I even thought too much about the Southern Annular Mode, about 14 years ago, I was working at the UK Met office in England, in Exeter. And yeah, a lot of my work was on the Northern Annular Mode, so I had a really good introduction to the annular modes through that project work there. I was there for two years and then came back here and started to look at the SAM and thought, "I feel like I've looked at this before a little bit," because yeah, there are a lot of similarities. It was easy to step into the SAM work here, having looked at the Northern Annual Mode stuff before.

Jemma Pearl:

The Southern Annular Mode is becoming more and more a part of the vocabulary when talking about conditions in southern Australia, but it has taken some time to get to our current level of knowledge.

Andrew Marshall:

that's a really interesting thing, thinking about the SAM and the early observations, the late 50s, 60s and 70s, when this work really got started, but it wasn't really until the 00s, until 2007, I think Harry Hendon and co-authors, published a paper that was really the first paper, I think, looking at the impacts on Australian climate in those different seasons. So yeah, it took a good 40 years or so before we really started to truly understand the SAMs impact on Australian climate.

Andrew Marshall:
I mean, even though the Indian Ocean Dipole was really first probably discovered in '99, I think it was, so a good 20 years after the SAM, our understanding of it and its influences on Australian climate has lagged actually. So it's been more that I think when we learn about the Indian Ocean Dipole, we learned pretty quickly about its impacts on Australian climate, whereas the SAM has taken a bit more time to understand, with regards to its local effects.

Jemma Pearl:

So, what are we talking about when we say Southern Annular Mode?

Andrew Marshall:

So around the Southern Hemisphere, around the middle latitude, so around the 45 degree south, south of Tassie, that kind of latitude around the Southern Hemisphere, we have these really strong westerly winds that we often call the mid latitude westerlies, or the mid level jet, sometimes you'll hear it described as.

Andrew Marshall:

These are the really strong winds that circumnavigate the Southern Hemisphere, and so you often get storms embedded within these westerly winds. So really, the position of these winds has a huge influence on those frontal systems and things, where those fronts, where they impact different parts of Australia or other parts around the Southern Hemisphere, they are really guided by the position of those westerly winds.

Jemma Pearl:

In 1957 the world’s research bodies working in the Arctic and Antarctic agreed to take and share more data. This year was known as the International Geophysical Year. This explains why the data for SAM pre-1957 is less reliable. Dale explains which locations we do collect data from to assist with the SAM.

Dale Grey:

Yeah. So, the physical data that we have that measures the SAM was the SAM Index, was invented by Dr. Gareth Marshall from the British Antarctic Survey. And he used a number of locations around the 40 degree latitude mark, and a number of locations in the 65 degree latitude mark down around Antarctica. And the difference between those ones was able to determine whether it was a negative or a positive SAM phase.

Dale Grey:
We would know some of the ones at the 40 degree line, places like Hobart and Christchurch. The next one round is Puerto Montt in Chile. And then we have Gough Island, Marion Island and Ile Nouvelle Amsterdam or the Island of New Amsterdam. And around Antarctica itself, we have places that we may have heard of before, like Mawson and Casey Station. We have Dumont d'Urville which is a French station and Mirny and Novolazarevskaya, which are both Russian. And we have Faraday, which is the British Antarctic Survey there as well, their station.

Dale Grey:

So the data from these ones is what first was used to construct the SAM Index, using actual physical measurements. These days, though, we just use the modeled pressure measurements at those latitudes, probably at much larger locations that just at those individual points. But that's the reason why the SAM Index doesn't go back farther than 1957 in terms of physical measurements.

Andrew Marshall:

it's been since the beginning of the satellite era, the late 1970s when we have been able to fill in a lot of those gaps and come up with more, I guess, coverage of the data around those regions, to get a fuller understanding of the SAM and how it varies.

Jemma Pearl:

There are three different phases of the Southern Annular Mode, positive, negative and neutral.

Andrew Marshall:

Positive SAM is when those westerly winds that circumnavigate the Southern Hemisphere, when they contract towards Antarctica or towards the South Pole. And when that happens, we see a drop in surface pressure at the higher latitudes, so over the South Pole, over Antarctica, and we see an increase in the pressure around the mid latitudes, so that's the positive SAM phase, and the opposite, the negative SAM phase is when those westerly winds, that westerly wind belt expands towards the equator. And when that happens, we see higher pressure over the South Pole, we get a drop in pressure around the mid latitudes. And so the transition between the positive and the negative SAM phase is when we see those pressure changes happening in concert with those changes in the position of the westerly winds.

Andrew Marshall:

And of course the neutral SAM phase is the average position of those winds, when we don't see those movements towards the equator or towards the South Pole. And these fluctuations, I should say, these meandering winds can occur over days or weeks or months, or even seasons. So the timescale really varies as well for these changes in the wind flow, and shifting north and south can occur over various timescales.

Dale Grey:

I'd like to think of the positive SAM, like the water going down the plug hole. The winds are getting faster as it's getting sucked into the pole, and anything that's in that area is getting dragged in closer to the pole. Now obviously, it's not going down and disappearing down the hole but it's that centrifugal motion I suppose where things are spinning faster and they're getting pulled in towards the pole. Then obviously the negative SAM is the opposite there. That force isn't there as much and it kind of allows those frontal systems to drift up closer to Australia a bit less unimpeded.

Dale Grey:

Positive SAM which is when those winds speed up, would indicate a big differential in temperature, so is that colder around Antarctica, or warmer at the mid-latitudes, or both?

Andrew Marshall:

Yeah, that's right. And that links really closely to the temperature as well, the temperature over the South Pole. So those winds and the speed of those winds really is coming from, I guess, the response to the temperature differences between the South Pole and the mid latitudes, and the stronger those temperature differences, the faster those winds can rotate. So it all feeds into the temperature and then the pressure relates to the temperature. And yeah, this is how you see all these different variables, all feed in and feed off one another to influence the movement of those winds and the speed of those winds as well.

Andrew Marshall:

I'd say it was mostly fed by the temperature over Antarctica. And this is where, what we see in the winter, particularly in the stratosphere, in the winter time, in our winter time, the stratosphere becomes quite cold because it doesn't see much sun. And so this is when we get what we call the polar vortex, so the stratospheric polar vortex. And over the South Pole, you have very, very strong westerly winds, and by very strong, I mean, they can be up to about 200 kilometers an hour, and they spin incredibly quickly around the South Pole. And when this happens, you see this drop in temperature, faster wind speeds, and it's not until about November, December that this vortex breaks down, with the return of the sun and the return of warmth to the South Pole. And so this all feeds into what happens at the surface and how the SAM responds as well to these temperature differences. So you really see this strong impact from the changes in temperature over the pole, on the SAM activity.

Dale Grey:

I think you've just described for me why I suspect we get that flip in the SAM's response in Victoria, that it does a particular thing in winter, but in summer it does the opposite. Is that to do with because we're getting the different way Antarctica's behaving because it sees more sun in summer and something changes? Is that what's going on, or not?

Andrew Marshall:

That's a really good question, that's not really the driver of those changes in the seasons. So the main reason for those different seasonal impacts is to do with the subtropical ridge, which is something else that we've got to throw into the mix here. Out of the equator, as you know, so the equator is, of course, a huge hotspot of course, because it's the hottest part of the planet, and so what we see is a lot of air movement from the tropics into the subtropics. So that's just out of the tropics, both in the Northern and Southern Hemispheres. So if we're just talking about the Southern Hemisphere, thinking about Australia, we have this airflow moving out of the tropics up high, and then descending down to the surface over Australia.

Andrew Marshall:

That's why generally over the middle of Australia, it's arid, it's dry because we see a lot of descending air, we don't see too much rainfall there. And this is known as the subtropical ridge zone, so the ridge connects regions of high pressure. So it's very high pressure over this region across Australia generally, and this is known as the subtropical ridge. What happens is when we move into the summertime, the monsoon develops over northern Australia. So we see a lot of low pressure centers forming over northern Australia, the rainfall moves in, these wind change and these monsoon lows push the subtropical ridge further south. And so what this does is then it shifts the mid latitude wind belt further south.

Andrew Marshall:

So it's like the monsoon moves in, it says, "Okay, you guys get back," and it just pushes everything further south. So that's why in the spring to summer period, you see different impacts to the SAM, compared to in the winter, because in the winter, the monsoon heads into the Northern Hemisphere and everything relaxes back a bit further north towards the equator. And so that subtropical ridge shifts further north, the mid latitude westerly wind belt shifts further north as well, and then you see these different impacts on Australia. So it's really driven by that position of the subtropical ridge, which then of course is influenced, as I said, by the monsoon taking shape in the summertime.

Dale Grey:

That explains in winter, that pressure ridge is more further northwards. The Antarctic air masses are closer to Australia and the negative SAM, which allowing the fronts to move closer to Australia can potentially make it wetter south of the divide in particular, and then we have the positive Southern Annual Mode spinning faster and pulling those fronts away, and potentially drying off that area.

Dale Grey:

Then we get to summer and the pressure ridge has moved further down and all of a sudden, the behaviour of SAM completely does the most bizarre thing. You get this flip where the positive SAM now potentially gives greater rainfall particularly to eastern parts of Victoria. Spring has a bit of an effect in far east Gippsland I suppose. During the positive SAM seemingly you get more of this easterly flow coming into that region out of the Tasman Sea.

Andrew Marshall:

Yeah, exactly, and that's how I can quite clearly see it in my mind's eye when I look at these rainfall patterns. Because as you said, in the winter, you see those dryer regions over the southwest and the southeast of Australia, associated with the positive SAM. Moving into the summer, those shift further south. So it's really just western Tassie that gets the drying impact in the summer. But that drying, as you say, over the mainland, the southwest and southeast parts, particularly the southeast, that's replaced by, as you say, this onshore easterly flow. And in fact, when you look at the winter signal, you can see that onshore easterly flow a bit further north. So it's more of that northern New South Wales, northeastern New South Wales region where you see some increased rainfall. It's not a huge spatial signal, but it is there, you can see it. And then as we move into the summer and the whole lot shifts further south, you can see that really developing quite strongly around the eastern New South Wales and eastern Victorian regions.

Dale Grey:

I think we did allude earlier Andrew as to how quickly the SAM changes. When you see the SAM graph it's this wiggling line normally that changes over a weekly scale normally I suppose, but it's not something that's sitting still very long Andrew. It's constantly on the move.

Andrew Marshall:

we do fairly well with predicting the SAM, considering that it occurs right across different timescales. As I mentioned earlier, well, as you just said, it can vary daily, weekly, monthly, seasonally, and it often can depend on what else is going on. So the SAMs influenced, for example, it can be strongly influenced by El Nino and La Nina. So when we have these El Nino's, La Nina's, we can see sustained periods of SAM activity. So La Nina, like we had last summer, typically gives us a positive SAM, so we can see a positive SAM response often. So the SAM has been positive for many months over the last spring, summer to early autumn, and then when we have El Nino, we often get the negative SAM phase. So that can give us extra skill for predicting the SAM.

Dale Grey:

I've often thought particularly in winter, the SAM is not something... I'm thinking as a farmer here... It's not something you can predict oh the SAM's going to do something therefore this is what might happen on the farm. I've often thought the SAM is something that's probably best looked back in retrospect. You go, "Gee, it's really quite dry and oh look. The SAM has actually turned out to be positive over many months during the winter." It's something that creeps up on you when you look back in retrospect rather than necessarily looking forward a fortnight and thinking, "What's going to happen?"

Andrew Marshall:

Of course, it depends on the timescale that you're interested in for any particular decision that you're making. So for those short term decisions a week or two out, then you can look at the SAM forecast and you can get a good indication of what's coming. But really, as you say, if you're looking beyond the month, then it's really not until about the spring and the summer when you're going to get predictability beyond that timescale when the SAM can really be drawn out across months and seasons, linked to other things going on around the place.

Andrew Marshall:

For any given SAM event, there are also other things going on and that's what can make it quite challenging at times to, I guess, to isolate its effects from everything else going on. So often you can see a SAM happening at the same time as an MJO event, or a SAM happening at the same time as IOD, or as you mentioned, a blocking event, and in the spring, you see SAM blocking often line up. So you do often see, when you see SAM activity, then you'll often see a block out over around the Tasman Sea and also possibly one to the southwest of Australia.

Andrew Marshall:

So there's a whole mix of things going on here, and that's really what my work does a lot of the time, is to try to tease apart these different drivers and to understand their individual influences, but also their combined influences. And I think it was Kate Doyle from ABC, who described the SAM as being the teenager of climate drivers, it's temperamental, misunderstood and increasing in strength. And I think that's actually quite a nice description for the SAM. It pretty much sums it up, I think, and pretty much agrees with what you're saying

Jemma Pearl:

Sometimes the Southern Annular Mode doesn’t behave as expected. Because one or more of the other climate drivers enhance or nullify the expected conditions locally.

Andrew Marshall:

I did a trip to part of the Pilbara and Gascoyne a few months ago and spoke to a lot of farmers out there. And something that I noticed when I was preparing for that trip, because I was looking at these different climate drivers, and part of my role was to talk about these drivers and their impacts on that region. And what I found was that when one driver is acting alone, there's not much of an impact on that part of the world. But when you see these combining drivers, you can see these compounding effects. And so you can see that happen, and we saw that in the summer of 2019, 2020, when we had a central Pacific El Nino event, which tends to elevate the risk of fire danger over much of Australia.

Andrew Marshall:

Also, the positive Indian Ocean Dipole has a similar impact, the negative SAM, a similar impact. And we even saw, at that time, the MJO in spring moving into a couple of phases, which also can give us higher risk of extreme fire weather. And I've just finished, I've just published a paper on this work actually, looking at these different climate drivers and their impacts on extreme fire weather, because we can see how they influence extreme rainfall or dry conditions, in this case, and extreme temperatures. So when we do get these compounding drivers, we can see these effects, I guess, reinforced by this mix of drivers. And the opposite can be true as well, where we might be looking at the previous month rainfall and it might be that we've seen pretty average rainfall, but we had two strong climate drivers, but it could be that those climate drivers had competing effects on this region, that ended up having average rainfall. So we can see these drivers interacting and their effects combining, or even cancelling out to influence rainfall over different parts of Australia and temperatures and other things too.

Jemma Pearl:

Andrew explains some of those classic SAM events and describes the conditions we experienced at the time.
Andrew Marshall:

So for example, if we're talking about the SAM in winter, so there was the middle of the year 2010, for example, where we saw a positive SAM, and this was during the development of that really strong La Nina event that happened in 2010 to 2012. And so what we saw was very strong low pressure over the South Pole, and of course, the higher pressure, the ring of higher pressure that passed over Southern Australia. And so we saw that classic impact on Australian rainfall, where we had drier conditions over the southwest and the southeast. So we saw some very dry conditions there, June to July of 2010.

Dale Grey:

It was quite dry in the Victorian Mallee that year. I know it eventually became wet, but for some people that was too late because the SAM had done the damage. It had stitched up the rainfall in winter before the La Nina and that sort of weak negative IOD kind of kicked in.

Andrew Marshall:

I mean, just looking at the rainfall signal over Victoria, I mean, most of Victoria was dry for that event. So yeah, that was quite a memorable event that one. Yeah, we have some other examples, if we're talking again about the winter but perhaps looking at negative SAM, there was July 2007, quite a strong event, and again, we saw impacts there. So we saw some wetter conditions over the southwest and southeast, but a really dry spot over much of the east, further north of that position. So remember I spoke about in the winter, we do get that rainfall response further north, so large parts of southeastern Queensland and northern New South Wales, actually much Queensland had very dry conditions. So that was another example.

Jemma Pearl:

The Southern Annular Mode affects not only rainfall, but temperature as well. Andrew explains how SAM influences extreme temperature and rainfall conditions.

Andrew Marshall:

I've done quite a bit of work myself on this, with regards to the extremes. About seven years ago, I did a fair bit of work on the impacts on extreme heat and a little bit on extreme rainfall as well, but yeah, mostly looking at temperature signal. What we find is that when the SAM is in its positive phase, we tend to get some cooler conditions over much of the country, and this is something that Harry Hendon and co-authors showed in their 2007 paper as well. But then I went on to look at extreme heat. Generally the extremes, particularly when it comes to extreme temperature, tend to follow closely to that temperature variability.

Andrew Marshall:

So during the positive SAM, you have a lower chance of having extreme heat conditions and heat waves, but when the SAM is negative, you tend to get those higher chances of extreme heat. So this is often because for the negative SAM phase, you can get both the reduced rainfall signal, particularly in the spring to summer over the southeast, but also you get stronger westerly wind anomalies, and so they can drive some warmer conditions into the southeast. So yeah, negative SAM, we tend to associate negative SAM with a higher likelihood of extreme heat conditions.

Jemma Pearl:

We know climate change is likely to affect the climate drivers, but the SAM appears a complex beast to nut out, and its long term changes on Victorian rainfall appear unclear.

Andrew Marshall:

We've had a positive trend in the SAM over the last say 50 years or so, and this is linked to both the loss of ozone in the stratosphere, and greenhouse forcing. I think a bit more so to do with the ozone loss, because we know that ozone gathers in the stratosphere, and we see a lot of ozone in the stratosphere over the South Pole. So when we've seen ozone loss over the years, of course going back a few decades, we had the harmful chlorofluorocarbons and the chlorine related to that chemical, interacted with very cold clouds and caused ozone loss in the stratosphere.

Andrew Marshall:

So what that does, of course, because the ozone in the stratosphere warms up the stratosphere, so we have a loss of ozone, it cools down and that polar vortex, those kind of winds speed up. And so what we see is generally those westerly winds speeding up in the SAM, tending towards a more positive trend. So that's what we've seen in, as I say, in the last 50 years or so. But yeah, this trend is consistently positive in the summer and it's been shown to be weakish in the winter, but it's still there. So there's been a lot of work that's been done to understand these impacts of changes in our climate and our warming trend as well, on SAM trends.

Andrew Marshall:

So another influence on that of course, is coming from expansion of the tropics. So we know with our warming trend, the tropics is expanding and that's also pushing these systems further south and that's that warming trend influence, that affects the wind flows. And so if those winds are being pushed further south, then of course that's affecting things like the water supply. Yeah, so when these things influence those westerly winds that circumnavigate the Southern Hemisphere, then they're going to then feed onto the SAM activity, and we're going to see changes in the SAM that are linked to the changes in those westerly wind flows.

Andrew Marshall:

So our key question, I think, over the last few years has been does the positive trend in the SAM, can that explain the decline in winter rainfall over southwest and southeast, that we know is there and we've seen. And there's been a bit of work done, say for Tasmania as well, looking at changes in rainfall and long-term changes in rainfall. So I think there's a lot of work still to be done there, in understanding the impact of these changes on different regions around the country, and I know there's a lot of ongoing work in research on that now. So I think watch this space and we'll learn some more about this pretty soon, I think.

Jemma Pearl:

We greatly appreciate Andrew spending time with us in this episode.

In the shownotes you can find the links to the Southern Annular Mode forecast and more detail about the SAM. You can also get in contact with Andrew if you would like to ask a question.
You can also get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 3: The 101 of climate change science

Jemma Pearl:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Jemma Pearl, and here we talk about all things climate and farming.

In this episode Agriculture Victoria’s, Graeme Anderson and I talk to Neville Nicholls about climate change science and more specifically how we know that the green house gases are warming the world. At first it might seem that our understanding of these processes is quite knew, but it actually isn’t.

Neville Nicholls:

John Tyndall was one of my favourite scientists and in 1859, I think it was, he gave a demonstration at the Royal Institute in England and he demonstrated that carbon dioxide and water vapor were what we now call greenhouse gasses. He didn't call them greenhouse gasses, but he pointed out that unlike oxygen and nitrogen, they both absorb and emit what we call long wave radiation now. He called it heat energy and he wrote these beautiful books.

Neville Nicholls:

He was a wonderful experimentalists.

Graeme Anderson:

What they'd noticed was yeah, we get energy from the sun during the day and that warms up the earth's surface but at night when the sun sets that heat that the lands absorbed during the day, it should just radiate back out to space. And what they were noticing then, they were pretty clever cookies these physicists, they just noticed that ... They said, "It should actually be by our calculations around 30 degrees cooler every morning. Most of that heat should just radiate straight back to space but it's not. It's still there. What's trapping that heat and preventing it from escaping?"

Graeme Anderson:

So, they started a bit of an experiment, which was basically capturing gases in our atmosphere and passing heat radiation through it in a chamber to see which of these gases is trapping heat and so one of the things they did. Well, 98% of the atmosphere is just nitrogen gas and oxygen so those two make up 98% of the atmosphere and they passed the heat radiation through those two and the heat slips straight through. So, they said, "Well, if our atmosphere was just nitrogen gas or oxygen gas we would freeze every night so these other percentage of gases." They called them the impurities at the time. Let's start testing them and started trying to pass the heat through those gases and they trapped all of the heat. It wouldn't let the heat through.

Graeme Anderson:

So, that was basically the discovery of greenhouse gases. This is back in the 1850s. So, those laws of physics, they hold true to this day and basically that's the natural greenhouse effect that there's gases in the atmosphere that trap some of that heat and keep our temperature the way it is.

Neville Nicholls:

They've been proven and proven and proven, confirmed time and time and time again. Yeah. And again, there's some wonderful characters in the history of climate change, as there are in the study of natural climate variations as well. Wonderful characters who went out on a limb and tried to work out what was going on, but yeah, Tyndall's observations and his experiments, yeah. You can find people duplicating Tyndall's experiments now using modern equipment but doing exactly the same thing that he did. So yeah, carbon dioxide, it's a greenhouse gas. Water vapor's a greenhouse gas. Methane's a greenhouse gas. Oxygen and nitrogen aren't.

Jemma Pearl:

Now if I am correct Swedish chemist Svente Arrhenious was the first person to make the link between changes in greenhouse gases and changes in temperature.

Neville Nicholls:

Tyndall of course never thought that humans would ever affect the amount of carbon dioxide in the atmosphere. He thought we were too puny to do that, but he thought and he says in his book that these variations in the constituents in the atmosphere might explain all of the variations in climate that the geologists were just starting to identify, past variations on the scale of the dinosaurs type of timeframe.

Neville Nicholls:

Now, that's wrong. The primary determinant really is probably orbital variations but the greenhouse effect can amplify these variations, so it's a partial explanation. Wasn't quite as dramatic as Tyndall thought, but yeah, he never thought. And Arrhenius is I think the first person who thought, "Yeah, humans are probably starting to affect it on sufficiently wide, large amounts to actually have an effect." But still, that's a very brave forecast back in 1896.

Graeme Anderson:

So, what sort of happened with what is a now eight billion humans on the planet and we've used a lot of fossil fuels and the extra emissions of some of those gases that are put into the atmosphere actually mean that there's more heat getting trapped and while the sun still sends us a similar amount of energy. It's got an 11 year solar cycle and stuff. But basically what's happening is a bit more of that heat is being trapped in our atmosphere and what they're measuring is that there's increased warming in our lower atmosphere and when you head out to outer atmosphere it's actually getting cooler out there. So, we're actually changing the ratio of energy that's leaving the system.

Neville Nicholls:

Then another guy called Callendar in the 1930s started doing the same thing and he was the first person who really collected enough temperature data to realize the world was starting to warm a little bit. And he, again, attributed it to fossil fuel burning. He was attacked mercilessly by my predecessors as meteorologists. Again, they just didn't believe this was feasible, so then he kept on going at it. And then people in the '40s and '50s, '60s repeated his calculations and confirmed that it was right as we got better and better understanding of how radiation is transferred in the atmosphere. Yeah, people confirmed all this stuff that had been going on for a hundred years but show how slow science can be at times.

Neville Nicholls:

People used to tell me that climate was a new science and I used to say, "Oh, probably the second oldest science we've ever had." After medicine, the first thing you'd try to do is work out how to fix this broken arm. But after that, you started to worry is there enough rain that we'll get enough antelope coming past this year. So I think climate science have been around a long time and modern climate science probably dates from the start of the 19th century as well it's an old science. I sometimes feel that all I'm doing is trying to fill in some of the gaps that my predecessors already had worked out.

Jemma Pearl:

Graeme has a great way to describe what is happening in the atmosphere and one we can all relate to.

Graeme Anderson:

So, I'll use the analogy, Jemma, of imagine two cars parked on a sunny day. Both of the dashboards are warming up and then those dashboards are generating, radiating off heat. If you imagine one of the cars got the windows down and one of the cars has the windows up, when you go to the end of the day to jump in one of those cars one will be a lot hotter than the other and why is that?

Graeme Anderson:

That's right, yeah. So, both those cars are getting the same energy from the sun, the same amount of energy hits the dashboard but the car with the windows up has really changed the ratio of how that heat can leave the car. So, adding more greenhouse gases to the atmosphere is just basically like winding up the windows. We're just slowing down the rate that that heat can leave and that means that we start to see increasing temperatures and I guess that's what's largely been observed around the world.

Graeme Anderson:

In most places we've seen over the last, especially last 50 and 100 years, increasing temperatures. 90% of that heat's gone into the oceans but that sort of trend and we're at the early phases of that. So, the whole story of climate change is, well if we keep adding more emissions then we're really going to start to increase the amount of heat but also then starts to have questions into, well how does that effect our longer term variability? We know what good old fashioned variability and what our rainfall records have done in the past but how might that change in a world that's a lot warmer? So, that's where a lot of the climate change modelling comes in to try and look at what happens if that.

Graeme Anderson:

Certainly, when you look at the last 50 years and changes in temperatures and weather, for the huge amount of science that's being done on it, it's sort of showing that you can only replicate the increases in temperatures when you include increasing the greenhouse gases in the climate models. So, there's been a lot of work done on that end. I guess that's why there's all this discussion and effort now going into making sure we choose a low emissions future.

Graeme Anderson:

The bit about the climate change stuff is we know there's areas where there's high confidence such as around that extra trapping of heat, so the future's going to be warmer, 90% of that heat's going into the oceans but it's actually going to be pretty warm on land as well. We know too about how the planet works is that if you warm up the whole planet basically, the tropics is the hottest part of the planet, the tropics along the equator so if you warm everything up, the tropics expands either side of the equator and it sort of nudges weather patterns closer towards the poles.

Graeme Anderson:

So, from Southern Australia's point of view, if you warm up the world basically, the Westerlies and that bring all of our South Westerly cold frontal weather along Southern Australia, that all just gets nudged 500 kilometers to the South for every certain amount of warming. So, that's just the physics of how the planet and the weather systems work. So, a lot of the climate change models, they're confident that we're going to have increased heat, we're confident that it shifts weather patterns pole wards, we're confident that actually when you warm up the atmosphere it means it rains heavier so it increases rainfall intensity but there's also lots of things that the climate change models aren't sure about and that's why there's a range of models in terms of some places predict a much greater amount of drying than others. Some predict greater heat extremes than others and some really don't tell us a lot about what will happen to core modes of variability such as the El Nino Southern oscillation and how the Indian Ocean pattern might change.

Jemma Pearl:

With all that extra heat in the ocean, what effect might that have on variability?

Graeme Anderson:
I was saying earlier 90% of the heat's being absorbed in our oceans. In the last few decades there's been increasing amount of heat entering the Indian Ocean and warming out in the central and Western areas of the Indian Ocean and that's a bit unusual. So, what happens is if you look at the last hundred years of Indian Ocean Dipole phases, which influences our wet or dry seasons. It means that if you've got areas of ocean out in the Indian Ocean that are perhaps changing to a point where they're not like they were for the last hundred years, it means that we need to prepare ourselves for not getting a repeat of the patterns of traditional variability. So, if more of the heat sits over on the Western part of the Indian Ocean then it has real impacts on how it might influence some rainfall in future. So, there's a lot of parts of climate change that aren't well understood except it just means that well, we've got to plan for a bigger range of variability in future.

Graeme Anderson:

In a world of eight billion people we know that there's always been natural variability and the ability to have droughts and heat waves and flood events and all of that. So, when you add climate change and the physics and how that effects good old fashioned variability, it just does add and puts a lot of extra pressure on our systems in terms of what sort of intensity of rainfall we've got to be able to manage for peak flows, how we manage for bigger droughts, how do we manage for increasingly bigger heatwaves and those sort of things. So, that's part of it.

Graeme Anderson:

We're always going to have seasonal variability in there but in a warmer world the dynamics of some of this changes quite a bit. So yeah, a lot of it will be driven by the equator. I guess part of the question though is that while the climate change and the modelling and the science is confident around some areas of it, there's a lot of uncertainty there, especially about there could be some bigger surprises in there that we haven't really discovered yet. So, from a practical point of view in farming we've just got to be prepared to understand, make sure we're good at reading weather forecasts, make sure we understand what's in seasonal forecasts and then taking what lessons we can out of recent trends and understanding what might be coming with climate change projections and then improving that in how we set up our farm businesses.

Graeme Anderson:

So, we can see a lot of great stuff that farmers are doing to basically get better set up to handle that variability and agriculture's done a great job growing a lot of food and fibre amidst some pretty tricky seasons in the last 20 years but when everything goes right we can grow more food and fibre than ever but within 12 months we can be having an absolutely horrible run of seasons or weather event, so part of it's just trying to set up a system for how do we cope with that greater variability.

Neville Nicholls:

Oh, variability. There are some things which are easy to predict really in terms of climate. There are some things which are a bit sus and some things which we really just don't know. I really don't know how El Nino and the La Nina are going to change. There's been a lot of work over 20 or 30 years trying to work out this and people have come up with ideas, but if you look critically at it, it's really difficult to get anything a strong idea of how it might change. So I think we're really still working on that. It's a work in progress and I'm hoping my younger colleagues will continue their great work and will get a better idea because that's crucial for the farmers.

Neville Nicholls:

If suddenly the El Nino gets worse or become more frequent, yeah, that's something we need to know about. Yeah, the farmers need to know. Unfortunately, I'm not sure we can say that very confidently as yet. One thing we can say with great confidence is we're going to be dealing with a warmer climate. We have no way of avoiding the warmer climate. Even if we stop burning fossil fuels now, even if we found some carbon capture and storage system that actually could work on a large enough scale, we've put so much in there, we're going to have to deal with a warmer climate.

Neville Nicholls:

What effect does that have? Well, it affects animals. It affects people. It presumably affects plants as well. Not as much as rainfall, which is the other thing which is more problematic. There are parts of the world where the models are extremely confident that it's going to get drier. The parts of the world which have Mediterranean climates, so the far west of southwest western Australia, southern Africa, the Mediterranean itself, parts of America. The models all predict a continuing drying and we've seen that drying now for 30 or 40 years as well. So the models which don't know the data in a sense that we look at, they're looking at it from a completely different perspective. They say these areas should be drying, so I think it's not something that we're 100% confident about, but there's a fair degree of confidence that some of those areas will get drier.

Neville Nicholls:

Large parts of Australia, we don't know because the models don't have a strong consensus. All over inland eastern Australia, for instance. The models are not coming up with the same answer. There's a wide range of answers. So I guess my two messages, I tried for 30 years to sell these two messages. On the one hand, we do know something about how our climate is changing and will continue to change. It will get warmer. On the other hand, that doesn't mean that every extreme of the climate is going to get worse. It doesn't mean that everything that will happen with the climate is bad.

Jemma Pearl:

So is it all bad news?

Neville Nicholls:

There are opportunities as well as threats from climate change, so we know heatwaves will get worse and that has really bad effects on people, particularly people who are my age. So it's not great. On the other hand, cold events are going to get fewer and that's terrific for people like me. Melbourne is not nearly as bad an environment as it used to be 30 or 40 years ago because it has warmed. Partly, that's because the city has expanded and got bigger, but there's also an element of global warming causing that to be improved. Yeah, fewer cold events, pretty good when you're trying to walk out on a cold Melbourne morning and thinking, "I don't need my gloves anymore because of global warming."

Neville Nicholls:

So I guess a nuanced. I just sometimes regret that there's not more of a nuanced understanding of what we know. That there are things we know with confidence. The world's going to continue to warm. There are things we suspect, like there are parts of the world that have been drying and we suspect will continue to dry. Rainfall overall, over the entire globe, probably should increase a bit. Not a huge amount, but it should increase.

Neville Nicholls:

There are going to be, at least in some parts of the world, more extreme rainfall events and thunderstorms probably but not a huge increase, again. And there are some good things about it and there are opportunities. There are opportunities for farmers. There are opportunities for all sorts of people to take advantage of climate change, not just to sit and think of it as a threat all the time. It's not just a threat. It is a threat but it's also an opportunity. I sometimes feel that those messages don't get through very much and I think it's unfortunate.

Jemma Pearl:

We greatly appreciate Neville joining us again on this episode. Graeme and I definitely enjoyed spending time and learning from Neville’s many years of experience.

In the shownotes you can find more information and links to climate change content.

You can also get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 2: El Niño does not equal drought

Jemma Pearl:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Jemma, and here we talk about all things climate and farming.

In this episode I talk to Monash Universities, Neville Nicholls, about the El Nino Southern Oscillation and more specifically what the El Nino phase means to conditions in Australia.

Neville Nicholls:

I'm Neville Nicholls. I'm an emeritus professor at Monash University in the School of Earth Atmosphere and Environment. I've been there since 2005, and before that, I'd spent 35 years in the Bureau of Meteorology. I was originally trained back in 1971 as a forecaster. Never did any forecasting. My family think Australia is much the better for me never having made a weather forecast. But I went straight into research and stumbled across the El Nino and droughts, and I've been studying them ever since, with a bit of climate change thrown in over the last 25 or 30 years as well. I'm retired. So that's what emeritus means. It means you can turn up, but they don't pay you, but I still retain some interest.

Neville Nicholls:

The important thing about El Nino is we can use it to predict the weather, and the main reason we can use it to predict the weather is because of the way it's tied to the annual cycle. So once it starts around March or April, it tends to build and build and build until the end of the year and then collapse early in the following year. So that gives the really crucial bit that helps us make predictions of droughts and tropical cyclone activity around the Australian region and many other parts of the world. It's this long life cycle, that it's not just a random phenomena, unlike most things in the atmosphere.

Neville Nicholls:

I've always thought myself, having a strong to very strong one about once a decade, El Nino, I mean, a strong La Nina about once a decade, and a couple of weaker ones on either side in there as well, and a few things where not much happens. But as with Australian climate, it's not a nice normal distribution. There are more droughts and floods in Australia, than there should be, and that's because we're affected by the El Nino. Everywhere in the world that's affected by the El Nino Southern Oscillation has much higher variability of rainfall or temperature it affects temperature, than other parts of the world. And that's why Australia's a land of droughts and flooding rains, is because of El Nino Southern Oscillation.

Jemma Pearl:

The term El Nino can be confusing as it means different things to different people, while also being one part of a wider system.

Neville Nicholls:

We're talking about a few things all at once. So it seems like a simple concept if we define El Nino, but it is several things, and people like me tend to use the different meanings interchangeably, just to add to the confusion. So, perhaps if I start with the simplest one.

Neville Nicholls:

The simplest definition is that it's unusually warm water in the eastern equatorial Pacific that occurs every few years, peaks around Christmas time. It's been known to the local fishermen and the local farmers on the South American coast for hundreds and hundreds of years. It's called El Nino because El Nino is Spanish for boy child, and so because it appeared around Christmas time, people attributed or once thought of it in a sense as the Christ child. And it brought unusual gifts to an area along the coast of South America. Once you get off the equator, there's normally a cold current that comes up from the south. And when El Nino comes, you get this warm water, which actually comes from the tropics. So you get tropical gifts if you like, appearing on the coast. So again, it was a gift. So for all those reasons, this thing was called El Nino, and that's one meaning of it. That's the local South American meaning, is that it's this unusual warm water that last months, but peaks around Christmas time every now and again.

Neville Nicholls:

We then have to get down to, how do you monitor it? So we monitor it one way with Nino indices, that's indices of sea surface temperatures along the equatorial Pacific. But we also use something called the Southern Oscillation index, which is just really the difference in atmospheric pressure between Tahiti and Darwin. And those things combined, those monitoring things are what we use to monitor this El Nino Southern Oscillation. So there's a whole variety of indices, some of which are clearly related to El Nino, some of which are, but aren't obviously related through their definition. So it's complicated, but I'm hoping it's not too complicated.

Jemma Pearl:

The question is, when did we first discover that El Nino affected Australian rainfall?

Neville Nicholls:

So perhaps if I can describe how I got into research in El Nino, and that was in 1971, when I'd finished training as a forecaster and decided never to forecast, went into research. In 1972, basically the first job we had in the research section of the Bureau of Meteorology I went into, was to look at a severe drought that was occurring in the Papua New Guinea highlands at the time. Now at the time Papua New Guinea, I think it was called a protectorate of Australia, and was about to become fully independent, and they were struck by this devastating drought, caused loss of many lives. And the Australian government thought they should do something about it. So they asked the Bureau of Meteorology to examine the drought and work out what's causing it.

Neville Nicholls:

And we looked at it and we wrote a report that said, "Well, it was a drought because there wasn't any rain or not as much rain as normal. And there wasn't as much rain as normal because there wasn't much cloud." And that's about basically what it was, about all we could say, until the following year. The following year, as data dribbled in from all across the world, I realized that 1972 had been a really strong El Nino event. So people knew about El Nino events at that stage, but we couldn't really monitor them in real time. Research vessels monitoring sea surface temperatures, but it would take months for us to get the data. So it was a year after the drought and after the El Nino, that we actually knew it was an El Nino that was related.

Neville Nicholls:

And I went back and looked at previous El Ninos and realized something that Sir Gilbert Walker, a meteorologist in India, had known a long time ago, that rainfall in this area was related to El Nino events and El Nino Southern Oscillation events. And then it's grown from there as people built models, statistical models and computer models, of how El Nino worked. Everything just got mixed up, and we end up with this idea that we call the whole phenomenon, ENSO or El Nino Southern Oscillation. But one of the extremes of the El Nino events, which is what the big focus was on for many years, was on the droughts rather than the La Nina side. So, that's one of the reasons why it's complicated.

Neville Nicholls:

Another reason it's complicated goes back further in time, well before me, back to 1877. And in 1877, there was a really severe drought in India, British controlled India, and Henry Blanford, who was the Indian meteorological reporter to the Indian government, what we'd call the director of meteorology now, he recognized how bad the drought was. There were big inquiries about this drought and caused a lot of political problems back in England. But he recognized that atmospheric pressures were very high over India and the surrounding regions at the time. So he sent messages out through telegram, I guess, to all the meteorologists that he knew of, basically in the empire, in the British Empire.

Neville Nicholls:

One of these messages came to Charles Todd who built the overland telegraph between Adelaide and Darwin, but was also the meteorological observer for South Australia at the time in 1877. He just put it away. He recognized that pressures were very high over Australia as well. Just put that little observation away until the next drought. In 1888, Todd wrote an article about droughts in Australia and had gone back somehow and found data and realized that Indian droughts and Australian droughts tended to coincide and usually in the same year. So they'd been in 1877, but also this one in 1888 and previous one. And that's really the first evidence we've got of someone recognizing these, what we now call teleconnections between climate in completely different parts of a world. And again, that was just put away. I don't think anybody ever found it again, that observation until I actually wrote a paper about the 1888 drought, a hundred years later.

Neville Nicholls:

But Blanford's successes continued to work on the Indian droughts and this very high pressure that was seen across India. And Sir Gilbert Walker in the 1910s and 1920s started to correlate everything with everything else to look at what was correlated with Indian rainfall. And he developed this index, this statistical relationship that he called the Southern Oscillation. And it was an oscillation between the Indian Ocean area and the Pacific Ocean area in pressure. So when pressure in India went up for a long time, it stayed down in the Pacific. And he recognized that this was related to lots and lots of weather events, including rainfall over Australia, rainfall over India, but also in many other parts of the world.

Neville Nicholls:

So for many years, the Southern Oscillation was what it was known as. This was probably up until the 1960s when other meteorologists realized that it was also related to this phenomena being investigated separately, this El Nino phenomena of occasional hot water or anomalously warm water in the eastern equatorial Pacific and realized the two were related. So they all eventually got dumped together, clumped in together called the El Nino Southern Oscillation. And since that's happened, it's been another 60 or so years of research, of people adding more confusion and occasionally a little bit of light as to what's causing what and how it can be used. So it has really long historical roots, and I really love the fact that an Australian was the first, back in 1888 to recognize these huge teleconnections across enormous distances that we now call the El Nino Southern Oscillation.

Jemma Pearl:

So the two phenomena started being officially recognised together as ENSO in the 1960’s.

Neville Nicholls:

Yeah, there's two stories of that. The conventional wisdom is that it was a climate scientist called Jacob Bjerknes. I always forget whether he's Norwegian or Scandinavian. Probably Norwegian. And he certainly wrote it down in the sixties, in about 1966, something like that. But the Dutch, who colonized Indonesia and were in control of Indonesia, had realized that they were related probably in the fifties. And there are a lot of reports written by the Dutch meteorologists, one in particular called Belaga, but they just sit there in libraries, never referred to. I suspect I'm the one remaining climate scientist with his interest in this area who actually remembers these documents. But they did a lot of terrific work relating El Nino and the Southern Oscillation, and realizing, yeah, they were a truly linked phenomenon, that it wasn't just one thing causing the other, but it was the ocean and the atmosphere interacting, which caused these big variations, and caused things like El Nino. So I want to attribute, first of all, Charles Todd, and then the Dutch meteorologists who were working in Indonesia at the time.

Jemma Pearl:

Now that we have better defined what we mean by El Nino, you are probably wondering how does one form?

Neville Nicholls:

The trade winds, are a dominant force over the Pacific Ocean. They blow basically from the southeast. When they hit the equator they tend to blow directly west. Doing that causes what's called upwelling. Just because of the way the earth rotates, if you've got winds coming from the east, along the equator, they tend to diverge. Instead of going straight along the equator, they fan out. That means you've got water leaving the surface of the equator, and so that gets replaced by cold water from below. And the water below is colder, so that keeps cool water right along the equator, a few degrees each side of the equator from the South American coast, basically nearly all way over to the western Pacific. So that's what normally happens.

Neville Nicholls:

But then if those winds from the east are disrupted, particularly over in the western side of the Pacific, you sometimes get anomalously strange westerly winds that sets up what's called a Kelvin wave in the ocean. And as a result of that, that disrupts the upwelling right across the Pacific, and it allows the ocean to warm up anomalously. There are a whole variety of factors, which cause that warming, but the major one is that this upwelling of cooler ocean is disrupted. And so suddenly the ocean all over the equatorial east Pacific and central Pacific becomes warmer than normal. So the driving force is what happens to the winds.

Neville Nicholls:

Of course the trick is what causes these changes of the winds in the western equatorial Pacific?

It's due to an interaction between the winds and the ocean very much around the Indonesian, New Guinea, far west Pacific region, I think, and to do with the change in prevailing winds. For half the year the prevailing winds there are from the east, the other half of the year they're from the west. It's just what's called a monsoon reversal of the wind. And it's a tricky thing, but those winds directly affect the ocean temperature. If they're stronger than normal, they cause mixing of the ocean, and so the ocean's surface tends to be a bit cooler. But in turn the sea surface temperatures there affect the overlying atmosphere. And they affect it in a way that was looked at by this guy, Bjerknes, who was one of the first people who put El Nino and Southern Oscillation together.

Neville Nicholls:

And you do the maths and you can see that, by looking at those interactions, you can explain some of the really, really crucial things about El Nino. And there are several things about El Nino. It's not a random thing. It doesn't just come and go completely randomly. It tends to start around March and April. It tends to last about 12 months long. It tends to peak around Christmas, no matter what index you use. Whether you use the Southern Oscillation index or any of the Nino indices, that's basically what happens. And that's a crucial thing that we have to explain with any explanation of what happens with El Nino, that it's not random, it lasts about 12 months and it starts and finishes around the same time. You look back at all of the big El Ninos that we've seen in the last 120 years, nearly all of them have that pattern. And I think you can explain that because of this interaction between the prevailing winds and the underlying ocean in the west Pacific, Indonesia and far eastern Indian ocean, I guess.

Neville Nicholls:

So that again has to be a part of the whole thing that we're trying to explain of ENSO and El Ninos is that there's clearly positive feedback from May through to November, but that feedback disappears and the El Nino starts it dissipate. My explanation of it is that it's due to the reversal of the prevailing zonal winds, the east-west winds over the west Pacific and eastern Indian ocean.

Jemma Pearl:

What do we know of the mechanism that actually causes it to be drier?

Neville Nicholls:

I think it's something that unfortunately we've never really tied down as well as we'd like to, but in hand waving terms, what happens is that you've got this positive feedback north of Australia. It's over a large part. It's still a long way from Victoria but it's a lot closer than the central or eastern equatorial Pacific. So, you've got this phenomenon that's caused by this large-scale tropical ocean atmosphere interaction stretching all the way from the eastern Indian ocean to the west coast of South America. And you've got two things happening through May through to November.

Neville Nicholls:

At that stage, this anomalously warm water is starting to appear in the equatorial Pacific and in the eastern equatorial Pacific, central equatorial Pacific. At the same time during an El Nino, the sea surface temperatures around northern Australia are colder than normal and that lasts through till the end of the year. And at the end of the year, you get a remarkable change that you suddenly get warm water around northern Australia at the end of an El Nino. That's one of the first signs that an El Nino is on the way out.

Neville Nicholls:

Now, that cold water is associated with very high atmospheric pressures over our region, stretching from India through to New Guinea and south to Hobart. So it's a huge area of very high pressure associated with that. It's high pressure, so it's a stable system so there's less cloud. You've got subsiding air over much of Australia, anomalously subsiding air, so all of those things act to actually increase the likelihood of drought over Australia.

Neville Nicholls:

If you've got a big patch, a long-lasting patch of high pressure, you're going to force the cold fronts to track further south, along with the rain depressions that normally bring us what rain we get. They tend to be pushed further south by this large patch of high atmospheric pressure. Now, it's a hand waving explanation but I think there's quite a germ of truth in there that that's what's happening. But it's not this little patch of water ... It's a fairly large patch in the eastern equatorial Pacific. It's not that by itself directly affecting the rainfall in Birchip. It's much more things which are closer by that are part and parcel of this whole phenomenon that we call the El Nino southern oscillation.

Neville Nicholls:

So while I said the El Nino's not random, I meant it's not random once it starts and the fact that it only starts over certain time year. It doesn't suddenly appear in November, for instance. It starts around March and April and I think that's to do with this changing prevailing wind.

Neville Nicholls:

But you still need something to start it off and that can be a random thing and it can be a partially random thing like the MJO, the Madden-Julian Oscillation which causes shorter term fluctuations of the atmosphere and the ocean all around the world, but particularly obvious around Indonesia and New Guinea.

Neville Nicholls:

I think almost certainly you get a big pulse from an MJO. That might affect the sea surface temperatures in a way that's just sets it right to actually start what's a positive feedback. So something happens. A change in the wind in the Indonesian region affects the ocean in a certain way and then you start to get the build up. They get bigger and bigger and bigger and slowly build up into what we see as an El Nino towards the end of the year. So yeah, I've no doubt that the MJO plays a role but I don't think we've ever been able to really tie it down and I think that suggests that it's not the only thing you can do to start it up.

Jemma Pearl:

Given Neville’s many years studying the El Nino, I wanted to know what were the key things he looks out for.

Neville Nicholls:

I'm probably a bit idiosyncratic and old fashioned with this and lots of my younger and smarter colleagues build computer models of the El Nino and they would put their faith in what the models are saying. And I'm increasingly drawn to that but my old fashioned view, if I was just looking at data, the first thing I would look at from April onwards is Darwin pressures. If a pressure Darwin is consistently well above average in April and certainly by the time you get into May, then it's time to start getting a bit concerned.

Neville Nicholls:

It's not the time to sell the farm but it's a terrific predictor. In 1982, a colleague and I were sitting there looking at very high pressures through May in 1982 and we kept on asking our northern hemisphere colleagues, "Is there an El Nino?" And everybody kept on saying, "No. Of course there's not an El Nino. If anything, it's going to be the opposite. It's all cool out there." And it wasn't until about a year later that people realized that the explosion of El Chichon, a South American volcano had corrupted the satellite images of sea surface temperatures and cooled them enormously. And it really was very warm under there.

Neville Nicholls:

So I've always had a fond spot for Darwin pressure because A, it's simple. B, we know how good the observations are because we take them and it's really simple. So April and May Darwin pressures. It's not perfect. Nothing about the El Nino is a perfect predictor and it's not something you want to bet your last shirt on, but there's enough information in there to make you think, "Are there things we can take a little bit more quietly this year or does it look like a year we can actually put more money into planting things?" So you can do things around the edges with a prediction even as early as that, I think, just looking at the Darwin pressure.

Jemma Pearl:

It is not uncommon to have two La Nina years back to back, but what about El Nino’s?

Neville Nicholls:

It's something I've always wondered about and worried about that yeah, we can go back and find back to back La Ninas without too much trouble. But yeah, much harder to find back to back El Ninos but I would hate any farmer to actually say, "Well, we've got through that El Nino, so everything's home and hose from now on." I'm hoping no one would ever say that because climate has a way of kicking us, as I'm sure all your listeners know better than I do. But just when you think you've got a hold on it, it does something terrible to you.

Jemma Pearl:

One thing that the Break team were interested in hearing from Neville about is what do we know about whether climate change in making it harder to predict El Ninos.

Neville Nicholls:

So I guess from my professional point of view, the worst thing about climate change is that it makes it harder for me to diagnose what's going on in the natural climate. The El Nino southern oscillation thing is part of a natural climate. It's been going on for hundreds, probably many thousands of years and we're just at the point that over the last few decades of getting enough of a handle on it to actually for it to be useful. Then along comes climate change and makes us really struggle because we're dealing with the same things.

Neville Nicholls:

One of our big indicators of how the climate system's working in the natural climate system is sea surface temperature, but if sea surface temperature's just gradually warming as they have particularly over the last 50 years, that just makes it hard for us to diagnose what's happening. And it makes the simple models that I tend to think of using statistics, it makes you really nervous about using them. And you have to then rely on the more advance computer models that my younger colleagues produce.

Neville Nicholls:

Yeah, so climate change, it's an issue for the way it disrupts the natural climate variability and our ability to diagnose what's going on. It does make it harder. The warming we've seen of a degree or more than a degree in the last hundred years, that's a pretty sizeable percentage of the variations in sea surface temperatures we get from year to year due to a natural variability. So it's something we have to think about coping with and work out if it's going to continue, how's it going to disrupt the natural climate variability in the future.

Jemma Pearl:

We greatly appreciate Neville spending time with us in this episode.

In the shownotes you can find more information and links to El Nino content.

You can also get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 1: Using soil moisture probe technology in pasture paddocks

Jemma Pearl:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Jemma Pearl, and here we talk about all things climate and farming.

In this episode Agriculture Victoria soil moisture expert, Dale Boyd, and I talk to East Gippsland farmer and soil moisture probe host, Dave Caldwell, about how soil moisture monitoring technology has been used on his property to maximise pasture production and efficiency.

Dave Caldwell:
So we are farming, primarily based at Lindenow South in East Gippsland. We do also have some country down at Maffra. It's a mixed family farming business. It's been in my wife's family since 1894 on this particular property, which is the main property, and then it basically operates as a beef and sheep business, primarily beef, and ultimately we produce cattle out to feeder and kill weights, and then down at Maffra there's a dairy business. Yeah. So we sort of run it all together at this point, but there's certainly plenty going on and we are dry land and irrigated in both locations.

Jemma Pearl:

Dave is a part of the expansion of the Agriculture Victoria soil moisture monitoring program into pasture systems, looking to better understand how soil moisture probe technology may assist in decision making for livestock producers.

Dave Caldwell:
I think we installed it in early 2018, and if you look at the rainfall data for this particular property, effectively we had reasonable rains up until April 2017, and then we basically carried through the 2017 season on soil moisture, and then it became evident from 2018 through until January 2020, just how little moisture we had available. So from a rainfall chart perspective, we were effectively the driest three seasons on record in effect. So it was certainly challenging to get the reference point of what a full profile might actually look like on the probe.

Dave Caldwell:
Observing the paddock and observing the readings on the probe, certainly through those dry seasons, you could see it after a small or moderate rainfall event, and probably just how quickly it disappeared, that response.

Dave Caldwell:
So I suppose it's the first agtech of its kind within the business we have been users, I suppose at the start, the first serious agtech was GPS in tractors and that's been in the business since about 2015. And then because we irrigate via pivots, we've got a lot of tech and automation in the pivot and irrigation side of things. So it's certainly the first of its type that's related to weather. Every other bit of tech we've got is purely operational.

Dave Caldwell:
We're pretty open minded to the tech stuff, so we're certainly not opposed to it. And I think stepping into this space was a natural progression, and obviously we've been fortunate to have someone like Dale, who basically runs it from a distance. So I think one thing that we certainly value in our business that has to go hand-in-hand with tech is the support side of things.

Jemma Pearl:

Dale has been working with soil moisture probe technology long before the implementation of the first Agriculture Victoria soil moisture probe in 2011. He knows a lot about analysing the soil probe numbers.

Dale Boyd:
Interpretation of the data is a critical component of it. And when I'm looking at the data collected from Dave's property there, it was fairly dry for the first two years. And actually, we've got an 80 centimeter sensor or probe there, and that deeper sensor, it only got activated after two years, when there was a significant summer storm, the volume of three inches, that was able to get the infiltration and penetration down, and that set us away for establishing a field capacity point reference.

Dale Boyd:
And it's always a question, how quickly can you start to utilize the information, and to establish the upper limits and the lower limits, are the threshold you're looking to establish, but what we could identify progressing through '18 into '19 was just the individual sensors. And yes, there was some infiltration, but generally it was on the low side and maybe getting down to 40, 50 centimeters, so it never built a bank. We were aware of that and you could start to structure some management adjustments with the business that way.

Dale Boyd:
And with the shovel, that was a pretty shallow assessment, whereas with the 80 centimeter long probe, we're certainly exploring and getting some great insights into the deeper moisture profiles. Something that it wouldn't have been understood or observed previous, so it's a real eye opener. With the capacitance values that we plot on the graph, we can still go to the next level and determine the water holding capacity of that soil. So, effectively, how full the bucket is. That's the next step for this, but those hour by hour readings are so valuable. And also, with the rain gauge that's located there as well. You can get a really good idea of the intensity of rainfall over the 24 hour period, so it's not just the total. It's just the way it falls as well.

Jemma Pearl:

Decision paralysis can set in when you are trying to determine a location for your soil moisture probe, but there are a few key things to keep in mind.

Dave Caldwell:
I think the concept of Ag Vic, Dale and his team looking for somewhere to place the probe came through to us locally via the BetterBeef Network, and I put my hand up in the local group to say, "Yes, definitely interested. See a lot of value in it." And then the site that we proposed here, we tried to pick something, a site that perhaps wasn't representative of our entire farm, but it was probably more representative of the greater district. We do have fairly varying soil types, so we tried to pick something that was at large representative. And then we also, as a group, we said, well, it'd be really valuable to have a probe on a fence line, and on one side, have some annual cropping or highly improved pasture, and then on the other side have a more permanent, I suppose, less improved pastures. So that was as soon as we said we wanted two different things on one side of the fence, we were able to narrow it down fairly quickly, and then the rest was up to Dale about where we specifically put it.

Dale Boyd:
For that particular site, we were looking for access, so it wasn't too far off the sealed road and down the farm track. We're keeping away from waterways as well, but as soon as I saw that fence line, it made perfect sense, that was going to be an ideal spot to position two probes, same soils. The point of difference is perennial versus the annuals. Dave's been able to certainly provide some significant monitoring differences by, some summer rain allowing the perennials just to utilize and produce some growth, whereas with the annual paddock, instead of growing weeds, they were actually controlled and that moisture was able to be conserved through that summer period. And it was cherry ripe for the autumn sowing of the annual pastures.

Dale Boyd:
So the rain gauge is at least the minimum you need to collect those rainfall figures to match up with the infiltration. It's a pretty simple and cheap add on device. We've got capacity to add additional bits of weather collection equipment as well with this site. It's got a 12 sensor port capacity, so there's scope to collect temperature, humidity and wind speed.

Dave Caldwell:
Weather is part of what we do, and I suppose our aim is to utilize moisture when it's available, and then how we manage to draw that across our business to create the greatest value. I think when you look at it, it's fundamentally really important. Ultimately, when you look at this particular probe, probably what it's allowed us to do is make some decisions a little bit earlier. The probe's not really going to do anything in a major projection fashion, although I would make comment that currently we've still got a full profile of an exceptional season here in East Gippsland, and we've got a full profile in December. So we're probably using that probe with the confidence to say, "Right, well, we can probably perhaps put in place a couple of chemical fallows through until the early Autumn," and we'd have utmost confidence regardless of rainfall that we've got some moisture to start with.

Dave Caldwell:
So yeah, there is a prediction. I think what's been really important is that we've been able to observe the probe and learn how things have behaved based on the probe and what we're seeing in the field, and that's something that will certainly factor into future decision-making.

Jemma Pearl:

Compared to the historical use of soil moisture technology in cropping contexts, livestock farmers have used the temperature information more than their cropping counterparts.

Dave Caldwell:
Since having that probe in, I suppose some of the guys have been farming in the district certainly much longer than I have personally, would say as soon as it gets below 10 degrees, the grass stops growing, and having something that regularly tracks the temperature has enabled us to absolutely understand that, and there's no word of a lie behind it. I suppose what we used for this winter is, is temperature the limiting factor? If we're under 10 degrees, then it probably doesn't really matter what we do, we're going to have very slow pasture growth. But then as soon as that temperature started to rise, which was delayed this season, why are we not seeing a response? Which it enabled you to look at perhaps the nutrient side of your pastures or the moisture availability. Yeah, there's definitely value in that sort of thing.

Dave Caldwell:
The other thing, we do a fair bit of fodder cropping, so we don't take anything through to grain, but we do three to 400 hectares annually of fodder cropping. And whilst it's probably not as crucial when it comes to the autumn, winter planting, certainly for the summer planting, it's been an invaluable tool. If you're looking at planting say, well, here on this particular property, we've used it for time of planting for millets and sorghums and things like that, and we've probably been able to prove against the district perception about how early you actually can plant some of these summer or mid-to-late spring plant fodder crops.

Dale Boyd:
They've certainly been closely watching temperatures, and we've been able to put the temperature sensor at a closer soil surface level too. So it is in the right hitting spot. And you can bring it back to that 9:00 AM reference, which is great.

Dale Boyd:
It's a relevant point for the location and the farm as well. They're spread fairly wide, actually, the actual soil temperature measurement's on the Bureau of Meteorology site. So it's great to have this in a relevant spot.

Jemma Pearl:

AgTech is moving fast, Dave explains his thinking about investing.

Dave Caldwell:
Look, it's not too far in the future for us. I think most, surprisingly is called a young farmer at 37, one of the challenges we face in our businesses is prioritizing investment in terms of most farmers are guilty of reinvesting a substantial amount of their return back into the business, and we're definitely a business like that. So quite often, there's always something else that is competing for that available capital, I suppose. We're certainly nearing the point where we've got on top of a few of the bigger things and as the business grows and develops that yes.

Dave Caldwell:
The younger farmer, ultimately they've grown up with more technology and I don't know that the desire is any different. A lot of these tech now, they're designed to assist us to make better decisions or reduce labour components. I don't think it's necessarily that there's not a desire from the older generations to have a look at this agtech. It's kind of the fear of the unknown, I suppose. And if I look at, for example, my father-in-law, who was born here and he's now 70 in his mid-70s, once you get him on the tech, he's interested in it, but because they don't necessarily understand how to fix it or how to approach it, they're not naturally drawn to it. It's not that they don't have a desire, it's just that they're not a seeker of it, I suppose, but once it's there... So, I think that peer-to-peer learning definitely gets rid of some of those concerns about having someone you could call who you know, who might be able to help you.

Dave Caldwell:
You look at the way farming's developed in the last 15 or 20 years, tech has to be a part of it, whereas for a lot of my father-in-law's generation, it didn't have to be. You could still make an acceptable return with a moderate risk without the tech. Whereas, the younger generation farmer is generally... and in our business, we've got two business managers that are 37 and 39, we're about making money and reducing the risk, making that money, and making as much money as we can to grow the business.

Dave Caldwell:
So now that that's become a bit of a drive, the tech has to be there to allow us to achieve that goal. Whereas some of the older generation, their goals are different, they're at a different stage in life. So I don't propose that we're all of a sudden going to see everyone over the age of 55 with a moisture probe, but they're certainly still interested in the data.

Dave Caldwell:
I think once you show the value, and I'd use GPS in tractors as one of the easiest examples, we've had staff, for example, that have never used it before, started within the business being very hesitant, and after two days, they're like the rest of us. If the GPS stops, we just stop working. Do you know what I mean? So if there's clear, defined value, I don't think it matters what age you are, you become interested in that piece of tech, would be my comment. But it's about understanding the value and showing the value and having that person feel the value as to how open minded they're going to be. That type of tech.

Dave Caldwell:
Fundamentally, if I use an example from this weather station, where it's located is probably only within a kilometer of where we've got 150 hectares of irrigation and we don't have probes under the irrigators. If you start to think about what other tech in the weather space we would add to a station if we did that, I agree with Dale, you've got to understand your rainfall and we found that to be really valuable, even just to have a platform that actually records the rainfall accurately about when it fell, how intense it was.

Dave Caldwell:
But ultimately, we also have soil temperature registered on that particular probe, and that's been fantastic. We've used that tool quite rigorously and that's aided us to make decisions about time of planting, almost this particular winter of 2021, we were quite cold and you were able to use that as a bit of a projector of are we likely to see pasture growth at this time of year, and are we not? So there's soil temperature's really important. And another one that on the irrigation, certainly we would look at adding. And I'm not sure what's out there, but evapotranspiration rates would be really important to that. So yeah, there's a myriad of things you can add, and they're all desirable, but I suppose it comes a little bit back to prioritizing the capital as well.

Jemma Pearl:

Visualisation of the data is very important. If the data is not in a way that can be easily understood, value can be lost.

Dave Caldwell:
On that platform, there's a speedo and it basically compares this year to last year, and where you are one year ago, where you were one month ago. And that additive has been fantastic because as you know, it's not uncommon to hear a local farmer reel off a rainfall event in April 2017. I can do it. So to have that be able to say to someone, "Look, we're actually drier than we were last year," or, "We've got significantly more moisture than we did in December last year," that really resonates. And I can't really explain why, but it certainly does resonate to be able to compare year on year and at different times of year.

Jemma Pearl:

If you are thinking of investing into any AgTech, there are a few key things to think about.

Dave Caldwell:
We touched on it earlier about how something works is great, but the rear support is fantastic. I think we're not terrible. In fact, generally speaking, I'd say I'm quite confident with troubleshooting and that sort of thing. So most of these issues, we'd be able to troubleshoot on our own, but it would take a lot longer. What I've found in the past is you can spend a lot of time trying to sort something yourself, but if you've got that backup support, one phone call might have you back up and going within five minutes, and it might take you an hour without that help.

Dave Caldwell:
So it's really important to have that there because what happens with tech is, it's pretty easy to say, "It's too hard." So you've got to be really mindful if you're going to go down this tech path that it's no different to a tractor. When we service our tractors, depending on how many hours they've done, and we probably don't put enough of that same approach towards some of the agtech, which I think it's really important to do. And if you do that, things do work quite well.

Dale Boyd:
it certainly is that backup support, and you're looking to collect that solid dataset, and continuing to track those soil moisture changes and weather obs, continuing through all parts of the different seasons. And the other thing about this technology is that you've got the capacity to do remote diagnostics. So I can be at the site, be on the phone and be instructed of some troubleshooting to identify and rectify any issues that are at the sites, so that's the beauty of that as well.

Dave Caldwell:
So you made the point that I might be good at fixing things. I still think I'm better at breaking things that I am fixing, because I always seem to have at least one to two things that are broken on the farm, so that suggests that I'm better at breaking them than fixing them. But yeah, it hasn't been a great deal. Dale and I have had plenty of conversations. Probably one of the greater challenges we've had here, we've got quite low solar radiation. So probably getting, I think, some of our challenges that we've had to troubleshoot are probably related to the fact that perhaps we need to look at how we're actually powering this thing in terms of how many panels it's got and that sort of thing.

Dave Caldwell:
And I don't know why, Jemma, that so many... I suppose it's because it's not mechanical is why you really have to be quite rigorous with some of these technologies. If they were mechanical and a turning wheel, we'd probably all naturally check the tyre pressure, but because they're not so mechanical, we tend to push it to the back of our mind. So I think it's an important point to make that any of these challenges you have with all your farm equipment, you just view it differently with different pieces of equipment.

Jemma Pearl:

One thing that has needed ongoing investigation on Dave’s property is the soil moisture probe and weather stations power source.

Dale Boyd:
South of the divide, rain days, cloud days, certainly putting pressure on the batteries with the lack of charge coming through those solar panels. The modem, which is the communicator, that's its largest power requirement. And if we just drop too low with the voltage, it can lose its settings, so just that bit of maintenance is just always required. All the prevention is also required with these monitoring points, so appropriate guarding and fencing. So stock can't rub up against it or chew cables.

Dale Boyd:
That rain gauge, because they're definitely low maintenance. They're not no maintenance, so just that routine monitoring, just keeping an eye that the funnels are clear, those bird spikes are preventing them lodging dirt in there, and insects. You've always got to be aware of insects. They can manage to get into any small little cracks. So just making sure all those seals are appropriately in place, and even a bit of a spray or ant dust as well, as a preventative. It all helps.

Dave Caldwell:
When we look, Jemma, at our irrigation for example, we've got electric pivots that put water out, and electricity and water don't go that well together. It seems crazy, the world's covered with electric pivots and electricity and water don't go together. This weather station's no different. There's an electrical component, there's obviously a water component, and certainly, when it comes to insects and ants and things like that, prevention's always much better than the cure. So fortunately for this probe, we have a fairly rigorous program in terms of preventing that stuff with all of our other electrics. So we say, "Right," and that's just gone on the list of things that Dale said, and when we have gone away from the ant powder, more towards the moth balls. But we do put things in there, early in the spring to try and prevent that.

Jemma Pearl:

One question everyone needs to consider before investing in AgTech, is how is the connectivity?

Dale Boyd:
So connectivity is related to the mobile service to transmit the data from the paddock onto the server, which is located in Melbourne. That was one of the checks we were doing at the time of assessing the site and its suitability, just determining the strength of the signal, how many bars was on the phone. It was quite good at that point, and so I guess we did take note of it. It can be frustrating if you got poor service. Because it is a static unit, once it ...

Dale Boyd:
It's going to transmit every hour. If we get a miss, we're hoping the data is at least logged and stored. And then the next hour it'll attempt to do that upload, and upload two hours or two lots of data instead of just the one. So there's ways of overcoming it, but I guess we're expecting technology and the delivery of data to be prompt, so expectations are pretty high. We just probably got to adjust them accordingly to, how good your service is.

Dave Caldwell:
Here in East Gippsland, connectivity generally is not an issue, it's the inconsistency of connectivity is one of the greater challenges. So in terms of here, we're not we're not remote and we look at certain towers, we can see them, and then we still have areas on the farm where the connectivity is really poor. So that's one of the challenges with all of this, and if you try and make your connectivity better for those areas, it's really quite expensive, we've looked at it. But certainly as Dale touched on where this particular probe is, there's there's really quite good connectivity.

Jemma Pearl:

The soil moisture probe has been set up on Dave’s property for over four years.

Dave Caldwell:
I'd certainly recommend some form of moisture monitoring in the soil to any farmer, but I would also say it's only worth investing in if you feel like you're going to use that data. There is a lot of tech out on farm that probably doesn't get used to its full potential. So that would be my one comment, find an area that you think is lacking within your business and then seek any tech that'll help you in that space.

Dave Caldwell:
I do genuinely believe there's a fairly good thirst at the minute for agtech across most sectors, is what I'm seeing. But sometimes the returns on agtech can be a little bit hard to calculate. If you go from a three meter seed drill to a six meter seed drill, well you can pretty easily calculate what impact that had as on your business. But, certainly something like a moisture probe, certainly before you've got one, it's quite hard to try and understand what sort of value it will bring to your business. And I think it's definitely surprised me how much value it's brought to the business, than what perhaps I initially perceived.

Dave Caldwell:
I think it's that midway point. So it's really easy go out there and say, "Geez, it's bloody dry," and really easy to go out there and say, "Geez, it's bloody wet," but it's about fine tuning that middle ground, which this probe certainly allowed us to do. I do think agtech in general, if you look at any of the biggest challenges in our business, there's usually some kind of tech that we could in to help us with that. So I think it's going to be a really important part of the ag journey in the next five to 10 years is agtech, definitely.

Jemma Pearl:

Through the success of the initial implementation of soil moisture probes in pasture areas, the network has expanded and will continue to improve soil moisture and temperature decision making.

Dave Caldwell:
The best way to learn as a farmer in my view is peer to peer. So having now six probes across East Gippsland, I think that peer to peer learning, which is definitely a fundamental of the Gippy Ag Group, I reckon watch this space, there's going to be a strong interest in this area, especially probably in some of the areas that are a bit more marginal or the climate variability is greater. So I think these sorts of things, watch this space, from my perspective.

Jemma Pearl:

We greatly appreciate Dave’s spending time to talk to Dale and I in this episode.

In the shownotes you can find more information and links to all things soil moisture monitoring.

You can also get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted.

For more episodes in this series, finds us and follow wherever you get your podcasts.

We would love to hear your feedback, so please leave us a comment or rating, and share this with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria and The Tribe.

Welcome to season two of My Rain Gauge is Busted

Welcome to season two of My Rain Gauge is Busted.

Here at My Rain Gauge is Busted we talk about all things climate and farming, and explore stories from farmers and researchers, about our weather, the seasons and the climate, about what’s normal and what isn’t, and the great work underway that is well setting us up for the future.

In this season, I, Jemma Pearl am joined by my colleagues Graeme Anderson, Dale Grey and Dale Boyd to talk to our guests about El Nino, Positive IOD, decisions making, climate change science, extreme events, soil moisture and the Southern Annular mode.

We trust there will be something in this season for you.

For more episodes, find us and follow wherever you get your podcasts. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

Season 1

Episode 8: Reality is that any model could be having a bad year

Ethan Berry:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Ethan, and here we talk about all things climate and farming.

In this episode Jemma and I talk to Seasonal Risk Agronomist, Dale Grey, about the Fast Break table, which is a tool he created when he was asked the question, “wouldn’t it be great to have an A4 table that summarised predictions from multiple models in one place?”

Jemma Pearl:

Dale took up the challenge and is now not only producing the Fast Break table for Victoria, but also South Australia, Southern New South Wales and Tasmania.

Now I promise if you have never seen the table, this episode is still for you. There are many different seasonal outlook models around the world and it is advantageous to know about them. As Dale explains its all about the vibe of multiple models rather than picking a winner.

But, first what are the different model types out there and what can they tell us?

Dale Grey:
Well, the first of the couple global circulation models, or the CGCMs in the lingo, and these are the big computer models. These are the computers that take over the basement of a large high story building somewhere in the capitals of the world. They're millions of lines of computer code and they are modeling the world on a grid in three dimensions, both up into the atmosphere and down into the ocean and spatially across the world. And using mathematics to obey the laws of physics in terms of heat and moisture and wind transfer, just one box talking to the box next door to it. And the wind goes here and the moisture goes somewhere else. So they're the CGCMs.

Dale Grey:
Then we have what are called the ensembles and they are groups of CGCMs, groups of coupled models. What it's been found is that you can group a number of climate models together and get a potentially better forecast than just trying to pick the very best model. And the reason for that is that by clumping a number of models together and averaging them, you remove some of the outliers if ones crazily dry or one's crazily wet, it gets ignored and you get a more balanced forecast from the ensemble.

Dale Grey:
So some of the ensembles we've got there such as the APEC one, which is a Pacific community one, which includes models from Australia and Japan and Korea, and over in the US, and then we have a European ensemble that includes a lot of the models from the UK Met Office and France and Germany and Italy. And then we have a North American ensemble, which includes a lot of climate models from the research institutes in both Canada and the USA.

Dale Grey:
The last one we have is we just have one example of that as a statistical model, I quite irreverently call these the back of the envelope calculations. They're far from that, they're much more complex than that, but they're basically looking at a reading of something, let's say for instance, sea surface temperature. And they have correlated or made statistical assessments of how that sea surface temperature has affected rainfall in a particular spot. So Australia, for instance. So you look at a pattern of sea surface temperature and when it's looked like this, the rainfall has looked like that. And when it's looked like something else, the rainfall is different and changed.

Dale Grey:
So the one that we do is the Queensland SOI phase system, where we're looking at the two months of the Southern Oscillation Index, whether it's going up or down or strongly positive or strongly negative, or sitting there doing nothing at neutral and how that's affected the rainfall over time. So it's just a simple single factor comparison between a couple of months of the Southern Oscillation Index and how that's affected rainfall historically.

Dale Grey:
So, there's been some sort of conjecture, I suppose, as to whether the statistical models are actually valid anymore. And we certainly saw that with the old Bureau of Meteorology statistical forecast, which was based on sea surface temperatures in the Indian ocean and the Pacific ocean. And the problem is since that model was developed in the late 80s, the physical ocean temperatures have changed what seems to be permanently out there.

Dale Grey:
And so the old statistical arrangement between sea surface temperature and rainfall no longer held when you did those forecasts for Australia. And particularly when they were looking at the temperature forecasts, actual physical temperature for the landmass that was nearly always predicting that to be really warm because the oceans around Australia were warmer than when they first did that first arrangement.

Ethan Berry: These are the three different types of models, but the real question is why look at individual models if ensemble models aggregate multiple models into one?

Dale Grey:
So the good thing about the global climate models is that they actually don't care about history. They don't care what did happen 20 or 30 years ago, they're just looking at right now, the temperature is X, the pressure is Y, the relative humidity is Z, and that means the world's climate and the weather will do something. So they're much more able to react to changes in the climate like we see, because, they have that sort of stuff, just the mathematics is just factored in. Perhaps the disadvantage with the ensemble models is that they do provide just a dumb average of six to eight models and so sometimes you lose the granularity where a particular model might be showing a nice rain shadow effect that south of the divide looks wetter, but north of the divide, there's no kind of signal.

Dale Grey:
And you might see three or four coupled models that might show that up, but when you put 10 of them together in an ensemble, you might lose that. So it's usually the individual models sometimes that can give you some better resolution or tell you perhaps some more information about a particular rainfall outcome that might get lost in the ensemble.

Dale Grey:
Of course, the other thing is that if the ensembles are all over the shop, well, they're just going to come out with a forecast of neutral, anything can happen. And may not tell you much at all, whereas individual models might at least tell you where that signal is coming from. You might be able to pick, "Well, where are the wetter ones? Where are the drier ones?" And then you might be putting some bias on those from your own experience as to which model you might be believing a bit more. But the reality is, if a model is coming up with a neutral forecast, it's not telling you a lot in terms of what might happen because the model has been run many, many times and that's come out with very equal chances of wetter, average, and drier.

Jemma Pearl: Of the coupled global circulation models, they can be further broken down into operational and experimental models.

Dale Grey:
So our fast break table is made up of two different types of forecast products. And the first of those are what we call the operational models and they are generally run and owned by the major meteorological agencies in a country. So for instance, that's NCEP in America, it's the UK Met Office in the United Kingdom, it's the Access Model from the Bureau of Meteorology in Australia. And they are putting out official forecasts for their countries, and because these are global climate models, they're putting out a forecast for the United Kingdom, but the whole world's running as well. So, we get to look at the forecast for anywhere in the world really. We're looking at south eastern Australia when we look at them.

Dale Grey:
The other type of model we have are the experimental models. And they're the ones that are made by research agencies around the world, often universities. So we have someone like NASA, not an official product from the US, but nonetheless, a very well-respected research agency. The one we have from, the other model we have from Japan, from JAMSTEC is from a university. From memory, I think there's a couple of other experimental ones as well. So it's really just a delineation between one's putting out a forecast and they're being kind and putting up on their website so the rest of the world can look at it, but it's certainly not an official forecast, which is what those ones are that are coming from the official forecast from met agencies from around the world.

Ethan Berry: One of the key things that can confuses people is the difference between a probabilistic and a deterministic forecast.

Dale Grey:
Out of the 12 models that I look at, when you go and look at their websites, they present their forecast in two different ways and some of them present them in both. And they're either probabilistic or deterministic. Probably easiest to start with the deterministic first. The models run 50, 100, maybe more times and all the answers for every grid point for rainfall are averaged out. And that is the deterministic forecast. It's the average of a large number of model runs, which is different to a weather forecast. A weather forecast is a deterministic model. The model for the forecast is run once and that's the forecast. That's it. There's no other answer, it's just what the model says.

Dale Grey:
But if you run those models often enough, which the medium term climate models are, and you average them all out, well, you get a big dumb average there which is the deterministic forecast. And if the majority of model runs are wetter, that deterministic forecast will lean towards the wetter, and those deterministic forecasts are nearly always done in an anomaly. How many millimeters less than normal or more than normal is this forecast average providing?

Dale Grey:
And so sometimes those models give you a large anomaly, in which case that's probably a higher chance that wetter might be for instance, or drier if it's a large drier anomaly. Often they just give you a bit of a sniff in one direction that, there's slightly less rainfall predicted compared to normal or slightly more, which doesn't give you a stronger signal that the models are all going in one direction, but what's interesting is that history tells me that often just that slight drift, that sniff towards something looking a bit drier or a bit wetter is often the way it's going to come out.

Dale Grey:
But the other way we have is the probabilistic one. And it's fair to say the majority of ones that I look at, I try to look at the probabilistic forecast rather than the deterministics where they're available. And the probabilistic one is when, once again, we run our model 100 times, but this time we start binning them into where they fall. So people would be familiar with the Bureau's access forecast that above or below the median forecast, that is a probabilistic one. And they've just binned that into two things, how many forecast fall above the median and how many fall below the median? And then they give you a percentage saying, "If only 30% are going to be above the median, well that means 70% are going to be below it.” That's a drier forecast sniffing in that direction.

Dale Grey:
But the other way, most of the ones that I see have what's called a tercile probabilistic forecast, which is where they've binned all those 100 model runs into one of three sections. And that's either the lowest third of records, the middle third of records, or the wettest third of records. If there's nothing going on and the forecast can't work out what's going on and it's just what historical variability has always been, that comes out 33, 33, 33, a 33% chance of drier, normal or average in the middle, or wet.

Dale Grey:
But anytime you get something deviating, so a 50% chance of drier, that means 50% of the models are falling into that driest third, rather than 33% that would normally. That's a really, actually a large increase in the odds of things falling into the dry category. Sometimes a large number of models fall in average. So, that model is actually predicting that average is the most likely outcome, although to be honest, that is something that models don't often do. They normally sit on the fence at neutral, 33% chance of anything happening, or they drift drier or they drift wetter, but it's interesting, average is somewhere, they don't often want to head.

Jemma Pearl: Neutral is a word many will have heard when it comes to a seasonal forecast. But it is also one that does trip many people up.

Dale Grey:
But it brings us to that concept of the neutral forecast. So that would be the word we would see in the fast break table the most. And particularly in autumn, models will be sitting on the fence at neutral, meaning, as I said, they've run it many times and the model can't see anything in the climate that's pushing it in any direction away from what has always happened, which was a third chance of dry, a third chance of average, or a third chance of wet.

Dale Grey:
And where we get into trouble, where people get in trouble is that it's very tempting to think that neutral means average. And I cannot be at any greater pains to explain that that is not the case. Average means average. Average would mean average in a deterministic forecast if it came out showing that there was no anomaly, either way, the average of all that deterministic model was that there was no deviation.

Dale Grey:
In a tercile forecast, average would be that the model was run many times and average actually came out as one of the most common model predictions. But as I said, that's not common usually. But more over we get what's called the neutral forecast, which is a 33% chance of average, a 33% chance of wetter, and a 33% chance of drier. People get frustrated with that but to be honest, if you're a glass half full sort of person, a neutral forecast is at least a 67% chance of it being average or wetter, as opposed to a 33% chance of being drier. So the odds of normality or better with a neutral forecast are running with you.

Ethan Berry: One of the questions that Dale often gets – given his study of the different models over such a long time – is ‘well, which model is the best one then?’

Dale Grey:
Well, I've been looking at individual models for some 15 years, every month of those 15 years. And so I've seen models come and go, and I've seen performance come and go, what people may not know is that at the end of each year, I assess how models have gone for Victoria and looked at each year, how they've performed. And we provide a little fake award that they don't actually receive, for which model has gone the best for the year. And there are some models that have literally never won that award and some that have possibly never come close. And there are others who've won it a couple of times and there's pretty been mixed performance, I suppose, that often each year in that time, it's often a bit of a different model gets up, but there's usually a clump of them that are what you'd call the front runners, I suppose.

Dale Grey:
And our own Bureau of Meteorology, the access model has done well and its predecessor, the old POAMA model. We have the UK Met Office from which the access model is derived from that's also done well, so has the ECMWF model. Interestingly enough, the SOI Phase System, the statistical model has not been disgraced in a few years, particularly when there's an El Nino or La Nina event on the go, particularly a strong one. The Chinese model has won one as well. So there's a suite of 12 models there, I've named about five or so, but by a difference you can guess that the others haven't actually won much at all.

Dale Grey:
So, the reality is that any model could be having a bad year. And the worst thing that could happen is that you're looking at your favourite model and it's saying something radically different to what the other nine are doing. And you'd have to be a very brave person to be saying, "I think my favourite model has got it right and the other nine have got no idea. They must be dreaming." It's more likely that the other nine are seeing something that your model is not seeing.

Dale Grey:
So I always look for consensus, rather than just picking one model and going with that, I'm looking to see what other models are saying to see if they're seeing the same sort of things and predicting similar things.

Jemma Pearl: With all this work to look at the different models monthly to create the Fast Break table, what gives Dale confidence when looking at the predictions?

Dale Grey:
When models are run, they give particular answers. And sometimes those predictions are plausible. They line up with multiple lines of evidence around in the world and you can look at what that model is predicting and go, "I can see where that model has pulled that prediction from." And there are other times where you see a prediction and you go, "I have no idea where that model has pulled that prediction from. It just seems to be coming out of thin air." Now of course it's not, but what it means is that what's causing that model to go that way is not blatantly obvious in many of the other signals that we look at.

Dale Grey:
So I think what's interesting is, if models are predicting an El Nino, often you'll be seeing a signal, particularly in the under sea of the Pacific ocean. You'll be seeing, if you look in the under sea of the Pacific, you'll be seeing warming underneath there and you can go, "Well, I can clearly see that if the trade winds reverse, that warming might pop up and form an El Nino." You instantly go, "Well, that's a plausible outcome that actually could happen." However, if it's really cold under the Pacific and models are predicting an El Nino in three months, likewise you kind of go, "Well, things would have to change dramatically from the way they look there at the moment for that to go in that particular direction."

Dale Grey:
So that's when it comes to a particular climate driver, but when it comes to predictions of wetter or drier forecasts, likewise you're also looking for lines of evidence for what might be going on. So if a model's predicting wetter, and there's currently an Indian ocean dipole negative in existence, automatically you'd link those two statistically and go, "Well, that means there's an increased chance of wetter, that's a plausible outcome. That's a plausible forecast to be coming out there."

Dale Grey:
But then you start looking, "Well, what's going on around Australia atmospherically? What's the pressure doing in the tropics? Is it lower up that way? Is the pressure lower over Victoria? Does that mean we're better able to bring moisture down?" Because if that's the case, that's a plausible answer for something could be leading to wetter as well. Is there an abundance of cloud to the north of Australia? Or if in the case of a negative IOD, is there an abundance of cloud coming off the island of Sumatra? Does that mean, even though we have a negative IOD, is it coupled with the atmosphere above it? Is the atmosphere doing the right thing? The trade winds, are they blowing strongly in towards Indonesia?

Dale Grey:
So you have these different lines of evidence that come together to give you confidence that, this forecast is probably going to be coming out right, or it's got a stronger chance of coming out, I believe what it's saying could actually happen because of all these other things I can see. As opposed to a forecast for drier, because there's an El Nino, but the SOI, the pressure is normal, the cloud is normal to the north of Australia and over the International Date Line, indicating that if it's an El Nino, it's uncoupled. The ocean's not talking to the atmosphere yet. This model thinks it's going to, but until the climate driver starts to couple from the atmosphere, it makes it harder to believe that the forecast might be right in the future.

Dale Grey:
So once again, you're looking for lines of evidence that line up confirming the forecast to what you would expect to see for that forecast to come through. Of course, models not much chop at predicting out to four and six months, because that's so far away that anything potentially could happen. And if a model is predicting something four to six months out, well, the reality is you won't see anything in the current climate probably to link that signal through. And so, predictions that far out are often... Well, they're not much more than crystal ball gazing often.

Ethan Berry:

We greatly appreciate Dale’s willingness to spend time with us in this episode to take us through some of those tricky definitions and to allow us to better understand what is involved in creating the Fast Break table.

With your new skills, you should go and test them out by reading the Fast Break table and checking out the different models. You can find links to all those things in the show notes.

You can also get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 7: I got chills, they're multiplying? Frost in South Eastern Australia

Ethan Berry:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Ethan, and here we talk about all things climate and farming.

In this episode Jemma and I, along with our two special guests discuss frost. While some industries like stone fruit require chill time. For the grain growing regions of south eastern Australia, frost is a significant risk to their productivity.

Jemma Pearl:

Frost continues to be a subject of much research as explained by Dale Grey and extra special guest Peter Hayman, Team Leader of the Climate Applications team at the South Australian Research and Development Institute, commonly known as SARDI.

Understanding how we measure frost can greatly assist in understanding the possible consequences in paddock, as Dale explains temperature can vary greatly across an area.

Dale:
So frost is measured, not surprisingly, using a thermometer to measure a minimum temperature. And historically, or since 1910 in Australia that's been taken in what's called a Stevenson screen, which is a white slatted box that's roughly one and a half meters off the ground. Interestingly enough, useless fact for the day starting early, a Stevenson screen was invented by Robbie Lewis Stevenson's dad, who was the author. Raising the temperature probe off the ground to take the temperature is really important because that changes the temperature compared to what it would be on the ground.

Dale:
Farmers would know that temperature dramatically changes with altitude and it really does because rising your temperature probe one and a half meters off the ground is enough to change the temperature by 2.2 degrees. So people might have often seen that the definition of frost is 2.2 degrees and wondered surely it's zero and that's right. No, things only freeze at zero. But when it's 2.2 degrees in the slatted box above the ground, that's when it's commonly zero degrees at ground level, hence you get that difference. But that's the amazing thing that to me anyway, that a one-and-a-half-meter difference in the altitude changes the temperature by 2.2 degrees.

Peter:
I remember reading in a book from the bureau that if you take your dog for a walk on a really cold night, it's walking through a much colder envelope of air than most of you are. And if you take your dog for a walk on a really hot day, it's walking through a much hotter envelope of air.

Peter:

So even under these very, very small distances of a few meters, we get this inversion, where it's colder at the surface and warmer aloft, the wine industry in New Zealand and in Tasmania use helicopters to push down the warmer air. So they're using helicopters that they just hang around in that time to just push that warmer air down. When people use smudge pots or something in horticulture, it's not to heat the air, it's to create circulation and let the warmer air above and this blanket of really dense cold air move.

Peter:
And a PhD student, Bonny Stutsel, working with Ben Biddulph in WA showed really nicely that, in a wheat trial, if you have a tall variety next to a short variety, you'll be incredibly careful because you can just get this air spilling off the taller variety onto the shorter variety and mucking up your results on a really frosty night. So these differences are happening over a micro scale, aren't they?

Dale:
Yeah, and that's why farmers see the influences of frost really changing dramatically with height and elevation. Generally, that cold air is denser and weighs more, and it travels in the lowest parts of the landscape along creeks lines and river valleys. But it could be just the lower parts of your paddock. And that small differences in elevation can be the difference between frost perhaps causing damage and forming, versus it not having any effect on the crop at all.

Ethan Berry:

As Dale and Peter have already touched on, it isn’t only the height that can affect temperature. But also physical topography and barriers within a paddock.

Dale:
So the zero-degree temperature at ground level can be affected by lots of things, such as stubble cover or insulative layers on the soil can affect the temperature. And interestingly enough, the science tends to show that stubble layer tends to make it colder. Because usually during the day, the sun is beating into the ground and the soil takes up heat. And it lets that heat go back during the night, which tends to prevent frost. But when that temperature escaping back at night is not warm enough and it goes below zero, a layer of stubble on the ground can help to insulate and not allow the heat back out, and cause the temperature to be lower than might normally be.

Dale:
The other thing that can affect the temperature is soil colour, surprisingly enough. Black soil takes up more heat because it's dark compared to white, sandy soil. And so it doesn't take up as much heat as well. And then the other thing is really just the moisture content of the soil. The more moisture that's in the soil, the more it is able to take up heat and totally dry soil is very insulative. It doesn't take up heat as much as moist soil. We tend not to see frost forming at ground level. When we have moist soil, particularly in dark, grey, self-mulching clays if it's able to give that heat back up during the night. But there's plenty of things in between that change that. Sometimes it's impossible to avoid the fact that a frost is going to form, even if you have moist soil and a dark soil, and perhaps no stubble cover. The conditions are such that you're just going to get a frost anyway.

Jemma Pearl:

There are a few keys things needed for a frost event to occur.

Dale:
So frost forms when some pretty specific things are in the case and the first thing you really need is cold air. And cold air, if you're at the top of Falls Creek or Mount Hotham, is quite common because you've got altitude to cause your cold air. But, in the flat lands where we're growing crops, most of the time the air is not cold. But it gets colder overnight because the sun disappears and we get radiation of the heat that's built up over the day, disappearing out through the sky at night. And the temperature drops at ground level.

Dale:
What the predetermining condition for frost often is though, is that we get this injection of very cold air just before the frost. And some of that air might be coming from Antarctica, or it has originated in Antarctica and somewhere we saw for 12 o'clock midday in the late afternoon, you suddenly get this injection of cold air, usually at the front of a high-pressure system with a southwesterly wind, which lowers your temperature already. So that when you get that radiation during night, you drop to a lower temperature than you would have, because you're starting at an already lower point.

Dale:
And the other critical thing is that you have to have a lack of wind. You can't get frost formation when it's windy. So that's why people are starting up their helicopters in horticulture. Sadly, we can't do that in broad acre. But when it's windy and if you're in a windy location of Australia, often a lot of coastal areas tend not to get frost, a little bit more wind activity. But in the inland areas, particularly you get that injection of cold air at the front of the high, and then the high moves across that evening. And you're suddenly in the middle of the high-pressure system, and there is no wind at all. And you get that re-radiation of heat back out to space and dropping the temperature down lower than it normally would be.

Peter:
the more important distinction is in Australia we're dealing with radiation frosts, that's not to say there isn't any advection going on. Whereas in, if people are reading some things from say North America or Europe, they have these freezes where you can get frost and wind. And again, it doesn't really matter where you stick your thermometer if there's a freeze happening because you've got this icy blast coming from the arctic. And there's a lot of damage in horticulture and crops in the northern hemisphere. What we're dealing with is are much milder conditions but then just this very cold night because we're getting ... the outgoing radiation. Which, as you say, you can almost feel that happening as that sun goes down around five-thirty or something, you just feel every little bit of warmth is being sucked out because you're equilibrating with outer space.

Ethan Berry:

The formation of ice crystals that cause damage to crops during a frost event, happens in an interesting way.

Dale:
Well, people might be interested to know that you can't get frost forming in a sterile environment. When frost is forming on a plant, at the core of those ice crystals, which can cause the damage are a bacteria, usually. You need something there to let the ice particles start and they're normally called an ice nucleating bacteria. So when the temperature gets cold enough, that little physical, imperfection that's around the plant, allows ice to start to form around that and to start to form a crystal.

Dale:
And of course the problem is with frost, why it causes damage is that when that ice crystallization occurs in between the cells of the plant, you get ice crystals forming, and they physically puncture the sides of the walls of the cells. And when things melt, the contents of those cells are all mixed up and cactus. And why we see physical death of plant material when that occurs. It's interesting that when you see white frost though sometimes, you see white frost in the outside of a plant. But the inside of the plant can actually be okay. It's actually managed to cope all right, and you actually haven't physically got ice formation in between the cells of the plants. So it's only when you get ice forming inside the plant and fracturing the cells that you get that really, normally by lunchtime that day, you will see the effects of the rapid death of that cellular tissue due to the fact that the cell walls have been irreparably injured.

Dale:
I mean, certainly the rain coming in before the frost can also be physically bad because you get water droplets trapped in the oracles and the leaf stems of the plant. So you actually get physical freezing of ice in parts where you normally wouldn't see it. So you sometimes see the ring burn frost where the head dies, because it's actually been burnt off by that little droplet, the flag leaf or something.

Peter:
Troy Frederiksen in Queensland has this quiz. He worked in frost for a long time. He has this quiz of is zero the freezing point of water? And we all say yes, but actually it's not. Freezing is the melting point of ice. So you want to calibrate a bit of equipment at exactly freezing, you have an ice bath where ice is melting in water and that's exactly zero. The extraordinary thing is that water can be in liquid form a lot colder than freezing. Many of us have done this experiment by putting beer in the freezer and it is liquid and then you pull it out and then suddenly it turns to ice. And that's a useful experiment to do to show that it can get a lot colder and still stay liquid. When you move it, suddenly it nucleates and you get the ice forming.

Jemma Pearl:

While it makes sense that ice crystals cause damage, the damage is not the same for each variety.

Dale:
I think what's interesting is that the different crops that we grow, do in fact, practically have very different frost thresholds with which we see damage. For instance, if you use wheat as a standard, barley classically gets frosted at a temperature that might be two degrees lower than that. And oats is even more resilient. It has the ability to cope with a temperature that's four degrees lower than that, which wheat can get affected. And some of these are physical attributes of the nature of barley and oats, the way their reproductive structures are around them when they flower. But some, I suspect, are different. Some might well be physiological differences in the way they're able to cope.

Peter:
Ben Biddulph in WA has done really interesting work. This sort of conundrum that we know that the relationship between frost damage, as Dale has explained really well, that frost damage is different to cold damage. The bad frost damage we see is largely because of just disrupting cells with the ice crystals. We see a complicated relationship between temperature accurately measured at head height and the level of damage. And so sometimes you get a cold temperature, you don't get the damage. Sometimes you do. And so we were talking earlier about how difficult it is to get the temperature right across the landscape. Even if you spent gazillions of dollars measuring that across the paddock, you're then still not knowing exactly whether you could get frost damage. And the one reason for that may well be this fact of the level of supercooling happening.

Peter:
If you Google "supercooling water" there's lots of experiments people show with high school experiments of doing this and then dropping something in and suddenly it crystallizes.

Peter:
And the supercooling is pretty amazing, the fact that any plant can survive freezing, that we have snow gums. I mean, if you put lettuce in the freezer, it's never a good outcome for the lettuce. Whereas you've got these plants that are able to survive incredibly cold temperatures and keep water in them in liquid form. So wheat is able to do that, it just is ... where this happens, and I think it's watch this space, from what's happening in WA as to understand that. And this is well understood in some horticultural crops, and whether you can spray beneficial bacteria that may be able to help with this situation. But it certainly highlights the point that, frost is just this incredibly complex thing to measure and predict. And one of those complexities is the fact that, even though we think it might be a really nice threshold problem, as soon as we get zero, it's not a threshold problem. And that's probably stochastic across the paddock.

Peter:

So certainly that difference between oats, barley and wheat. One comment some people are making is that barley is probably more tolerant for head frost but maybe even less tolerant for early grain fill. And one thing I think we have learned about frost is that perhaps in the past we've been overly focused on the frost that happens around anthesis. So that's clearly an incredibly sensitive time and experienced farmers in frost prone areas are very concerned if the wheat's flowering and there's a frost that night. But there's a window that goes quite some time before that and quite some time after that. And that's where less determined crops like canola and so on. So sometimes people will say that an early frost on canola doesn't worry them much because there's an ability of the crop to just put out more flowers and so on, but a very late frost is much more damaging in that situation.

Peter:
So I think there's differences in the phenology and so on. But I think you're right that one of the reasons that oats, it just is a good design in terms of having the panicle the way it is is probably a good design for dealing with frost. But it's a, as people will point out that when you get the incredibly cold night, the really severe frost, nothing much helps. I remember a farmer in Junee told me it took him a long time to work out how well sheep handle frost. And the role of livestock and even just crops for hay and so on are an important part to that risk management. Which most farmers in frost prime areas, are right across.

Ethan Berry:

Peter explained that the climate drivers do have some impact on frost frequency, but the statistics don’t stack up when discussing the final frost of the season.

Peter:
As Dale has explained, I mean, we see frost on a still, clear, cold night and we would expect more clear nights in an El Nino year than a La Nina year. There's more nights where we're going to have less cloud cover there. And that tends to show the case. And most locations, if you just ask the question, are there more frost or fewer frosts? Or some sort of measure of daily frost sum, like summing up all the days below zero or two degrees, you tend to get a higher number for El Nino than La Nina and for IOD positive than IOD negative. And that's just what you'd expect with cloud cover.

Peter:
If you asked a question about the latest frost, it's not as neat. And I guess it's just as farmers understand, that late frost it's horribly jagged and horribly random and so on. So the question is, is the year going to have more frosts? El Nino will help you with that. If the question is about the latest frost, it's less clear. Some of the worst late frosts in some locations have been in La Nina years and so on. It's just more random. Because these late frosts, there's an element of just being these random weather events that come along all wacko.

Dale:
You sometimes have runs of multiple frosts in those really dry El Nino or positive IOD years, and that's when high pressure is really dominating the climate pattern. And so you're getting more slower, getting multiple days of injection of that cold air at the front of the high and no wind at night. And so you're getting those runs of three or four frosts in a row, which you tend not to get in the wetter years when systems are generally moving much quicker across the landscape. You might get one frost, but you're unlikely to get two or three in a row because things are changing too quickly in the weather pattern.

Peter:
As most farmers will point out, the dry droughty spring is the one they worry about the number of frosts. In some ways, it's actually the frost in the good year that really hurts you. Again, I've learned lot from Mick Faulkner on all of this. If you've got a drought and you've got ... you're looking at a ton of wheat or two ton of wheat or something compared to that when you're ... where people have got five, six tons and a paddock of lentils there and so on. And then suddenly, whack, it's worth nothing. That frost has proportionally cost the business an enormous amount because. Whereas, in the extreme drought, it's adding insult to injury but you've had the injury already from the extreme drought. And it's hard but it is some of these frosts that have hit us in these good seasons that are extremely costly.

Jemma Pearl:

Many people are right to point out that climate change projections show a warming of temperatures, but in recent times south eastern Australia have experienced more frost.

Peter:
So if you look at quite a few documents on some of the climate change projections for the southern grains belt, it will talk about frost reducing, yet it is certainly the case, and farmers are right to point out, that they've seen more frost in the last decade in many cases. And that's real, lived experience. I guess just a couple of quick comments on that. Firstly, a lot of things are changing. The emphasis on earliness in terms of sowing early and moving to quicker varieties. And also the varieties which we are very dependent on are very temperature sensitive. So if the winter and the spring is a bit warmer, they move along much more rapidly. And so you're combining those aspects. Good agronomy grows bigger crops, and as Dale's talked about, the stubble cover and these big, healthy crops and so on are also, all things being equal, favouring the level of damage and so on.

Peter:
So another climate scientist said, "Oh, well, we'd expect it to disappear within the next 20 years or something." Now, that's still a long time for a viable grains industry to deal with. That's a very small time in climate history but that being a lingering problem over that time is still a very significant problem. Another said, "Well, we'd certainly expect heatwaves to increase faster than frost to decrease." And especially as Dale was explaining, these radiation frosts are something that are very much linked to what's happening with the synoptic systems in the cloud and so on.

Peter:
So I guess what I'd see is the message is frost is hanging around as a problem, it's really causing significant problems for many grain businesses. I'm cautious about saying there's been a step change in the likelihood of frost because they'll go back and say, "Where's the real data for that?" and so on. And I don't think we have clear data for some sort of step change in the likelihood of frost. We know things change at a decadal sort of level and we know that it's still lingering there. I think we have to be cautious about being overly confident about what the next stage is. But we certainly have seen in the last decade some really worrying and severe frosts.

Peter:
I guess the other point is that so many as ... I remember a farmer from The Mallee said, "We used to have frost, eelworm, crown rot, all these problems. With rotations and better varieties, we've solved all our other problems so frost becomes a residual risk, which is hitting people too." So I think that's an important consideration. But an important question is, is frost becoming more frequent? So Steve Crimp from CSIRO and now at ANU has done really interesting work supporting that idea.

Dale Grey:

Perhaps it is because the lot of, you know drier springs we have been having there has been a lack of cloud cover?

Peter Hayman:

Or is it, as Dale pointed out earlier, frost is partly just about the high-pressure system but it's also about this in-feed of this very, very cold polar air from a long way south and very high in the atmosphere and drying it out.

Ethan Berry:

What is heartening to see is the innovation and intuition that farmers have already shown in tackling risk mitigation when it comes to frost.

Dale:
And I think that's where the advent of yield monitoring has really shown quite specifically in many years where the line has been between frost and not frost. I know for some people it's allowed them to consider actually taking areas out of production and really where things are getting frosted every year, well, why would you keep backing up to get the same results? So, some of those creek line and really low-lying areas, some people have actually chosen not to grow sensitive species there at all, or chosen only to grow hay, or to actually take them out of crop production and just put them in pasture and leave them for that. But it's only when you've got that information that it actually can tell you what those paddocks are and where the lines really are. But they'll be absolutely to do with the elevation of what those paddocks have.

Peter:
I guess an important point is, as farmers know much better than me, hay is a tricky enterprise. In 2019, with the widespread eastern states drought, I think there were grain crops that were cut for hay because the hay prices were so good. In 2020, with the wet October, it was the opposite. So we had two years recently where you could hardly go wrong with hay in one year and it was very, very hard to go right with hay the second year. And obviously it's very much where people, are in their enterprise and what they can do. But I think the understanding the zoning and looking at those options and so on is an important part of understanding the local landscape and how frost is varying spatially is obviously a really important part.

Jemma Pearl:

Along with farmers, researchers are trying to provide tools for better and earlier decision making.

Dale:
Ideally, you're looking for something that within three days of the frost or something, is showing up allowing you to make those decisions. And so whether that's satellite, or airplane, or drone, or a combination of those is a bit, well, it's uncertain at the moment. That's where the research question lies as to how you can assess a crop for frost damage remotely and quickly.

Peter:
There are a number of projects looking at how to to assess the level of damage from frost very quickly for making the decisions about hay. But also what the animal nutrition people will say is the decision of when to graze, is that going in quickly has benefits. So Hamish Dickson makes a point that actually responding quickly after a frost has benefits, rather than waiting too long. So quick identification and where to identify but also a benefit of this identification is obviously the tactical response in that year. But it's also the information about the paddock, and going back to Dale's point about zoning into the future, about thinking how that can be used. So the advantage is if you like both immediate and tactical for that season, but also strategic for longer term planning. Because it's given you some indication about where that has been and the level of damage.

Ethan Berry:

Frost can be a significant burden on grain production in south eastern Australia. We hope in this episode we have been able to explain some of the science behind the phenomena and some of the different things being investigated to assist growers to mitigate this risk.

We really appreciated Peter and Dale’s assistance with this episode to tease out some of the different aspects of frost.

You can find more helpful links in the show notes and you can get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcasts. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 6: The negative Indian Ocean Dipole is not all negative

Ethan Berry:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Ethan, and here we talk about all things climate and farming.

In this episode we explore the negative Indian Ocean Dipole, one of the best know givers of north west cloud bands.

Jemma Pearl:

The Indian Ocean Dipole is a relatively newly understood climate driver. So we caught up with Dale Grey who has been watching the IOD become more prevalent in climate communication since the Saji et al paper in 1999.

Dale Grey:
I've been with the department some 25 years now I think. So, a bit of a fossil. Been working in climate now for more than 15 years, mainly in the region of looking at climate forecasting and seasonal climate indicators and the stasis of the oceans and suchlike. And yeah, it was around at the time that the Indian Ocean Dipole first became a climate driver that people were suddenly talking about and thinking could be important.

Dale Grey:
Myself and my colleagues were up at a climate conference up in Canberra and Doctor Peter MacIntosh from CSIRO Atmospherics from Hobart. He was presenting some data where he'd been, him and his colleague, Gary Meyers, Doctor Gary Meyers who was also at Hobart's CSIRO had categorised the years where this phenomena called the Indian Ocean Dipole had appeared. And also El Nino and La Nina for that matter.

Dale Grey:
So there was this list of years that you could look at and it was the first time I think that we'd even heard of such a phenomenon called the Indian Ocean Dipole. So we were on a fairly quick learning curve there. Yeah, it became possible to use that list of years to get out your Excel spreadsheet and look at rainfall, and discover that low and behold the Indian Ocean Dipole had appeared to have been affecting rainfall across Victoria, in many regions in South-Eastern Australia, for that matter. Much the same that El Nino and La Nina had been also affecting the rainfall.

Jemma Pearl:

Like any new research the findings caused a lot of interest and a bit of discussion.

Dale Grey:
It was interesting because at that time, there was probably a fair bit of scepticism in the part of most people that El Nino and La Nina were even something of any note in Victoria. I think there were people who probably thought that they didn't affect the climate all that much. It was a Queensland thing. And so for those people to suddenly hear that there was a climate driver in the Indian Ocean where everyone thought their rainfall came from, was an attractive thing for a lot of people because it was telling them what they wanted to hear, I suppose. What has panned out in the fullness of time is that absolutely El Nino and La Nina are very critical things in Victoria. They absolutely affect our climate and the Indian Ocean Dipole does as well. And what is interesting, I'm sure we'll discuss is how that sometimes they act together in those roles. They're sometimes tag-team at getting up to mischief.

Dale Grey:
People have had been noticing things called Northwest cloud bands and that's when you see this big stream of cloud coming in from anywhere from Shark Bay up to Broome. It's coming in from the Northwest and when they're good they come right through the center of Australia, through you know Alice Springs and Coober Pedy and they come down into Victoria. And I think simplistically many people when they view those cloud bands make the assumption that moisture is coming down that Northwest cloud band and it's coming from the Indian Ocean, because that's where the cloud is coming from.

Dale Grey:
Now what it turns out is that the visibly seeing cloud is just a manifestation of the atmospheric processes in the sky which allow moisture in the atmosphere to be visible. What it doesn't show you is where the invisible moisture that's up there in the tropics is coming from to form that Northwest cloud band. And what has been shown is that the moisture in that Northwest cloud band may well have come out of the Coral Sea over in the Pacific Ocean and worked its way through the top of Australia, and then got hooked down in the Northwest cloud band and the pressure and the temperatures are right for that to form cloud.

Dale Grey:
And it looks like it is streaming out of the Indian Ocean, and the cloud is streaming out of there, but the moisture may have come from something else. Now, what the Indian Ocean Dipole has been shown to do is that there are a couple of phases, that we call it positive and negative Indian Ocean Dipole. And the negative Indian Ocean Dipole tends to be a switcher-on of those Northwest cloud bands. And the positive Indian Ocean Dipole tends to switch them off. And so in many cases, it's really that mechanism of transporting moisture down. Who knows where the moistures come from, but the mechanism transporting it down to us seems to be being controlled by this Indian Ocean Dipole phenomena.

Ethan Berry:

Dale explained that there are two specific regions on the Indian Ocean that Saji et al. defined.

Dale Grey:
So we have these imaginary boxes that are sitting, in the case of at Sumatra, we have a box that's sitting 10 degrees below the equator, and it's measuring the temperature in a box just below the island of Sumatra. Over off the coast of Africa, in fact, off the coast of Somalia and Kenya, almost up to the horn of Africa, we have a box that's twice the size of that Sumatran box and it sits plus or minus 10 degrees of latitude, either side of the equator. And what we're doing is we're monitoring the temperature in those two boxes, and unlike El Nino and La Nina, the threshold in the difference between temperature of those boxes is much smaller for positive and negative IOD. So, the threshold is deemed to be somewhere when it's greater or less than negative or positive 0.4 degrees Celsius.

Dale Grey:
So, negative IOD events, at least in Australia, are categorized by the Dipole Mode Index, the DMI, that's the fancy term we use for the difference in temperature between that box of ocean off Sumatra and the box off Africa. And when it's been less than negative 0.4, more negative than that for a period of eight weeks, that's normally when we would classically classify a negative IOD year. So, it can't be just sort of a flash in the pan, it's got to be around for a couple of months. And that's the one thing that characterizes negative IODs and positive IODs for that matter, they are phenomena that can be around for two or three months, whereas most events in the Pacific Ocean would last a lot longer than that.

Jemma Pearl:

The thing that many people find confusing is that a negative IOD generally has positive outcomes for south eastern Australia.

Dale Grey:
Well, we have this strange thing that the negative IOD was clearly not named by Australians. Oddly, if you are going to be naming it for Australia, you've got to flip that on your head and go, there's plenty that's positive about the negative IOD. It's often the bringer of rainfall and the sort of sister cousin of La Nina in the Pacific ocean. It was discovered in 1999 by the Japanese. Saji et al, they put out their paper, and then people from the US, from NOAA, Webster et al, they put out a paper at the same time, and they'd all observed very interesting things happening in the Indian Ocean in 1998. It was a very strong, positive IOD, as well as an El Nino that year.

Dale Grey:
But the Japanese gave it that negative thing, really because the difference between the temperatures in those boxes, when the temperature difference is negative, that's the negative phase of the IOD, but we don't know as much about it as we do about El Nino and La Nina.

Ethan Berry:

One of the best examples of a negative IOD year is 2016, one that many will remember as very wet over large areas of Australia.

Dale Grey:
2016 would be the most recent negative IOD of note, it was just a negative IOD event by itself. Then we'd go back to 2010 was the next one, but that was coupled up with a La Nina in the Pacific Ocean. Then we could go back to 1992, was the last time we had a very strong negative IOD previous to that 2016 one. And then we could go back to, say, 1974, where some people might remember, which was also one of those classic, double up events of La Nina and a negative IOD combined.

Dale Grey:
Humans are beasts of their memory, so as soon as you hear the word negative IOD, you kind of think about that. A bit the same as if you mentioned La Nina, people think of 2010, '11, and '12, and the really incredibly wet summers people had there and the fact that there were floods. And of course, the reality is that not all negative IODs have, in fact, been like that. There's occasionally negative IODs that have been quite dry. And in fact, 1943, which is a fair while ago, it was an El Nino like negative IOD. It was really quite a poor year over much of Victoria.

Dale Grey:
Like all the climate drivers, sometimes the absolute opposite occurs, but with the case of the negative IOD, it normally really does spin up greater chances of it being a wetter spring, but sometimes a winter as well.

Dale Grey:
It's interesting, because there is an area of Victoria and Southeast South Australia where, at least in our historic record of over 110 years, there's areas there that have never, ever, ever had a dry spring when it's been a negative IOD, it's either been wetter or average. And nowhere else can you really see a climate driver in Australia that has had that effect. There's nearly always the opposite appearing somewhere, might only be one year in the record. Sometimes it's two or three or four, but that Southwest, and really, the Southwest quarter of Victoria, I say that quite broadly, it sort of from Hopetoun, Longerenong across to Wedderburn Warracknabeal, and down to Hamilton, Warrnambool, Portland, and then over to places like Mount Gambier and Robe and even Bordertown and Keith in South Australia, so that Southeast corner.

Dale Grey:
Yeah, a really amazing thing that a climate driver has never, ever been dry in those zones. So therefore, those people, anytime there's talk of one, I suppose they're getting quite excited, because historically it's probably been a pretty good year in those times. The rest of us though, we would need to be keeping in the back of our mind that occasionally negative IODs are not all beer and Skittles and at sometimes they have been drier, but they are more likely to give wetter conditions than La Nina statistically. You more likely have odds of anywhere from sort of 50 to 75% of being in the wettest third of records for your spring rainfall. Most La Ninas, places locations to be about 50%, but the negative IOD spins up the odds even perhaps a bit more than that, so if we've got 75, then there's sort of a 10%, 15% chance of it being normal rainfall and sort of five, 10% chances of it being in the driest third of records.

Dale Grey:
Which brings us to perhaps regions of Victoria, where the negative IOD may not historically have had much influence and that brings us to East Gippsland. So, there's a really good reason for this, it's because the negative IOD is the best known giver of Northwest cloud bands.

Dale Grey:
Poor old East Gippsland to the Northwest is sheltered by the great divide, so this climate driver, the negative IOD sends moisture from the Northwest, which lights up the areas to the north of the great divide with greater chance of rainfall, but tends to, now shouldn't say it misses out in East Gippsland, it's just that statistically, the chances of rainfall fallout very close to climatology. A third of the negative IOD years have been wet, and clearly, even though that Northwest pattern's been there, the great divide has not been enough to stop it. But a third of the time, negative IODs in East Gippsland have been normal rainfall, and a third of the time, they've actually been quite dry, which might be perhaps those weakened negative IODs where they came down and they weren't able to get over the divide and cause it to rain too much in spring.

Jemma Pearl:

So you are probably thinking what exactly do we need to see to have a negative IOD, and what is happening in the oceans and atmosphere?

Dale Grey:
Well, essentially, to have a negative IOD, you have to have warmer water at the surface in that Sumatran area. And you need to have at least normal, but preferably cooler water, over off the African region. And the reason this is important is because this then starts an ocean atmosphere feedback mechanism, because that warmer water off the coast of Indonesia, of Sumatra, evaporates more atmospheric moisture upwards, there's lower pressure in that area, we would therefore see more cloud building up in that region. We're seeing the trade winds accentuating and swinging and sucking into that uplift zone around Indonesia, so the westerly trade winds increase as they're coming from halfway across the Indian Ocean over Indonesia.

Dale Grey:
The other thing, of course, is that we have much warmer ocean to depth off the island of Sumatra. And so, that gives us some of the predictability to the negative Indian Ocean Dipole. When you can detect a large amount of warm water at depth, as a result of the Argo floats that are going up and down every week in those areas, picking up much warmer water to depth.

Dale Grey:
And so, that's what we see this year in the potential negative IOD event that we have here in 2021, there's a really large amount of warmer water to depth, which the models can see. And if there's some sort of disturbance that gets some of that water to upwell, that can help to potentially kickoff and hold the negative IOD. Of course, what we see off the coast of Africa is the exact opposite of that. We start to see air that's falling, it's denser, it's got less moisture, so we get higher pressure and colder water over off the coast of Africa. We see a lack of cloud and we see the wind moving away from that area and over towards Indonesia. We may even see colder water to depth off the coast of Africa as well, so that what's coming to the surface is cooler too.

Ethan Berry:

Many different forces can be acting on the Indian Ocean, which can help to kick of a negative IOD or work against it.

Dale Grey:
We see a lot of negative IODs coupled up with La Ninas. And for this reason, scientists believe that the Pacific Ocean is possibly talking to the Indian Ocean. I'm using the word talking in inverted commas, because clearly it isn't talking, but it is acting on the Indian Ocean. The only way it can really do that is through those little gaps through the islands of Indonesia. And particularly there's a gap that's in between the island of Sumatra and Java. And if there's a large pool of warm water, that's sitting as a result of La Nina in the Western Pacific that can be dribbling warmer water through that Indonesian throughput gap and have it coming out in the box of ocean where we look for the negative IOD.

Dale Grey:
And so, that's clearly another mechanism as to how a negative IOD can form. Negative IOD formation is a bit more of a dark art, because it is just an accentuation of the normal phase, much the same as La Nina is an accentuation of the normal pattern in the Pacific Ocean, whereas the positive IOD and El Nino in the Pacific for that matter, abrupt reversals of the normal pattern, which are normally kicked off by something weird happening with a bit less predictability. Whereas the negative IOD seems to have a lot less mechanisms for forming, or at least we don't know about them, if there are more of them.

Dale Grey:
So the Indian Ocean is not as deep as the Pacific. The Pacific is some many kilometres deep. Much of the Indian Ocean is not as deep as that, and it doesn't have the long reach of wind between the land masses that the Pacific Ocean does as well. And so for that reason the Indian Ocean is liable to get affected by disturbances much quicker. So for instance, we don't see Indian Ocean Dipoles occurring over the Northern Monsoon Season. So somewhere from let's say November through to April. We don't see Indian Ocean Dipoles, as a rule, occurring at that time because the tropical processes of the Maddern Julian oscillation and things like that going up there simply disturb that ocean up so much that even if it wanted to form a pattern like that, it just breaks down too quickly. We tend to see them forming between the months of May to November, but normally May to October.

Jemma Pearl:

One of the interesting things about the Indian Ocean since observations have been collected is the increase ocean temperatures.

Dale Grey:What's interesting is the whole Indian Ocean basin has been slowly warming up, perhaps more so than some of the other oceans in the world. On average, it's warmed by about 0.6 of a degree. Interestingly, though, the very centre of the Indian Ocean has warmed by one degree, which actually really quite a large amount. And that's happened in the last 40 to 60 years.

Dale:
What we've seen in the last 20 years is a lot more positive IODs than the negative IODs. There's been a lot of positive IODs and whether that's because the ocean has warmed up more and whether that central Indian is having an influence of it probably remains to be seen. But yeah, all those positive IODs haven't been a real bonus.

So negative IOD events, we had a strong event in '92, we had a weak one in '96, but then we didn't see anything until 2010, so there was something like 14 years there between actual negative IOD events. That was a pretty long patch of time to go without one. And then 2010 wasn't overly exciting either in terms of its negative IOD. It was a pretty weak kind of event. It was much more of a La Nina year that year.

Dale Grey:
And so, '92 was a very strong event, was really 2016, where we got the proper first really strong negative IOD by itself, which is a really long time between negative IOD drinks there, whereas many more positive IODs in that period. And, of course, that's when we have colder water off the island of Sumatra and much warmer water off Africa. And of course, the problem is, because Indian Ocean has had a lot of warmer water in it, there seems to have been this sort of perpetual abundance of warmer water, particularly over on the African coastline. So, it would look like, to get actual cold water off Africa is something that I've not really seen that greatly.

Dale Grey:
But fortunately, at least, I suppose an actual proper negative IOD doesn't seem to be predicated on absolutely the water having to be cold on Africa, it's the differential. As long as you've got really warm water somewhere and normal water somewhere else, that's enough to drive the differential in temperature and a difference in the evaporation and the wind changes and the cloud and the pressure changes still occur, so that's probably the comforting thing I suppose. But the more worrying thing is that this warmer Indian Ocean just seems to be drifting more towards, or just makes it easier, it seemingly does, to cause positive IODs to occur. At least in the last 20 or so years.

Ethan Berry:

As Dale has explained a Negative IOD can actually be a positive for south eastern Australia, but no two negative IOD events are the same while they do spin up the odds of being wetter, it can also be dry.

We greatly appreciate Dale’s willingness to spend time with us in this episode to explain the Negative Indian Ocean Dipole.

You can find more helpful links in the show notes and you can get in contact with us at the.break@agriculture.vic.gov.au.

See you next time.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 5: Ten years of soil moisture data has greatly assisted decision making

Ethan Berry:

This is My Rain Gauge is Busted – a podcast produced by Agriculture Victoria. I’m Ethan, and here we talk about all things climate and farming.

In this episode we explore the value of soil moisture monitoring technology, especially when a seasonal forecast has low skill or is not really saying much.

Jemma Pearl and I sat down with Agriculture Victoria’s soil moisture guru, Dale Boyd, to hear his tips and tricks about soil moisture.

Jemma Pearl:

Dale has always had a keen interest in irrigation and the strategic applications of water, doing so through monitoring the plants and production.

Dale Boyd:

I was fortunate enough to get an irrigation line of work that we were looking to implement a whole range of devices, to test the market to find out what was out there. And that was to be tested in the irrigated environment that was not just crops that was pasture, summer cropping, lucerne production, all those kinds of things. We pretty much implemented about 10 different devices and telemetry units. And to be fair, that was probably a whole mixture of results out there, but there were certainly enough good success stories that really gave me the idea that this sort of technology, predominantly used in irrigation, had some benefits and potential in dry land.

Dale Boyd:

But those success stories with the irrigation was some of that strategic application of water, particularly to lucerne on the shoulders of the season with the autumn start-up. The right time to apply the water coming out of winter, which was hard to get a gauge of where those moisture profiles were. And then at the end of the season, in that late autumn period, exactly when you still got to get a result from applying water and also just being cautious of not having that soil profile too wet moving into winter, because lucerne wouldn't tolerate the wet conditions. So that was a great learning. And just also I can remember there was a wet year, a la nina year. The farmer was growing some irrigated corn. And I think, from memory, he might've saved or reduced the need to apply water to that corn crop by about half from his normal applications.

Dale Boyd:

One, because he was watching and observing the plant water use by the corn. But then he was a pretty good weather observer. So he was able to work out, okay, this crop is about at that refill point, needs to have water applied to it. But in a la nina year, the rain forecasts were quite strong and, when they come through, they were depositing rain of up to 50 mm, which effectively did the benefit of what an irrigation application would have done. So it was a great result. So it was a really good learning to be implementing the technology and watching the farmers grow with that.

Jemma Pearl:

On the back of this success, the Agriculture Victoria soil moisture probe network was established. Dale was given the challenge of testing the technology in cropping paddocks across the state, which began in 2010. The program has encountered some interesting questions and has continued to grow over time.

Dale Boyd:

There was about 10 bits of equipment that we tested. And I found one that had proven itself quite good. And to the point where the farmer had the measurement point put on his farm, but then he'd actually expanded the network on his own place to then monitor not just corn, but lucerne and another crop. So I thought, well, there's the proof in the pudding. He's happy with the technology. I'm happy with the way it works. So we went down the track of using that type of capacitance probe and with a graphing interface that was pretty much set up for irrigation, but I knew the principles of what I wanted to implement for dry land, knowing we couldn't apply water, but rainfall was going to be such a critical component of part of that measurement alongside with the moisture probe.

Dale Boyd:

I knew I wanted to measure deep moisture because that was the unknown. I know my farming background and working with my father, we always had a shovel with us. And when we're inspecting just to try and validate and check what the conditions were, it was really just the shovel depth. So that was measuring or observing the top horizon, maybe going down to 20, 25 centimeters. So it was really below that, which was the unknown. And that's what I wanted to test. And by having the probes that were long enough and could measure down into that depth of soil was going to be the real test for those dry land environments. Yes, so from those original nine sites being commissioned, the other strategy that I implemented at that time was to have them position quite deep into the soil profile.

Dale Boyd:

So the farmers could safely sow over the top and cultivate or do whatever they needed to do, but I was so keen on not having the probe disturbed because I knew, once it was in place, we'd collect these set of numbers and they should be repeatable, providing the soil isn't disturbed. And that's been the game changer. So a sub surface probe. Previously though they were capped stuck above the ground. The farmers either had to sow around them or they were removed. We also did farmer focus, little meetings within the district around that probe, because it was still new data. I was really looking to test to find out what farmers thought of it. Could it be accurate? Could it be beneficial? And we got some great feedback to say this is really opening up our eyes to what's happening deep below the soil surface.

Dale Boyd:

And with that, we then commissioned more sites, being more targeted for probably target some different soil types and different rainfall zones. We're certainly seeing benefits in those low to medium rainfall zones. And to the point where there was about 16, there were 16 cropping sites, which created a really good spread across the state and across a fair range of rainfall zones. So low, medium and high. I think on the back of implementing that cropping program, the extension of not just only presenting and providing talks at grower meetings, but also implementing newsletters that I'd look to provide an update of what the probes were indicating, which was then providing some insights into the season. But I was also thinking that the end game is to have more monitoring points implemented privately by the farmers. So that newsletter is looking to be educational.

Dale Boyd:

So we had some good runs on the board and then I was approached to then say, well, it works and we're getting good adoption, good understanding with cropping farmers. What about pasture guys? And so that's where we looked to then put in a pilot, targeting the medium to high rainfall zones and probably pasture types that were perennial. So with the capacity to grow all year round, just to see what was happening in terms of their moisture use. But also some good validation points that, not only just looking at perennials, but maybe pairing up the sites and looking at some annual growth of pastures as well, that rely on that autumn break to get them started. Watch their root development, winter production into spring.

Dale Boyd:

And then maybe we could then find that point where the way the moisture is being used, the outlook, you could say in two weeks, four weeks, production is just about to come to a completion. And just to start that forward planning of whether you need to look at stock numbers, supplementary feeding, all those sort of planning.

Ethan Berry:

One of the brilliant and super interesting things about this soil moisture probe network is the years of unbroken data which has significantly increased our understanding of what is happening below the surface.

Dale Boyd:
10 years of generally unbroken data is pretty unique and it's really showing some insights into the seasonal variability that we're dealing with. When I look back, we've had it all. We've had the really dry years, 2014, '15, 2018, really challenging years. At times water doesn't even meet that 30 centimeter sensor. So it shows that it does need considerable amount of rain to start to have an influence and be registered with the moisture probes. But then we've got 2016 that was so wet and then carried moisture into 2017, and then just what we've experienced 2020, another favorable year when we can pick up these moisture changes and the infiltration. And occurring so early, it really sets the season up and allows the farmer then to put on and apply the right amount of inputs because it's really showing some high yield potentials, especially when it's that second half of winter and we're starting to get the indications from the climate models of some outlooks with some more confidence.

Dale Boyd:
And then we've just had the average years as well. So every year is different but, in a way, every year the collection of data, it just adds so much more value to that monitoring point.

Dale Boyd:

The data that's been collected to this point has been showing great repeatability in terms of its accuracy. So we've been able to establish those critical thresholds that we're looking to do again with the cropping scenarios. So when the soil has got its capacity of water holding to a full point, so you can set that as an upper limit and then those lower limits that are generally achieved in that late spring, summer period. Depending on the season, that's the point where the plant can't physically extract any more water. So we've got the plant-available water. And then we can just rate that as a percentage and give anyone who's of interest the percentage of what the profile is in terms of being full.

Jemma Pearl:

Investigating soil moisture at depth has including many days in the paddock taking soil cores, with interesting results.

Dale Boyd:

I can remember, I know that the coring tubes that I've used to validate the capacitance probe data has played such an important part in the host farmers gaining confidence in the data, and getting that visual and physical inspection of their soils and their profiles that change down to depth. And just the roots as well.

Dale Boyd:

And they're so visible and I know that, in the better years, when we get a great break and there's moisture down to depths that might be tapping into residual moisture from the year before, the plant growth above the soil surface is pretty extraordinary. But the root extension and the development that's occurring below the soil is also as remarkable. So we've found that there's a theory that, with wheat, it will have a root growth of one centimeter a day, potentially more from emergence. And that'll progress providing those no restrictions, whether it's constraints. And that can be from dryness or hostile soils, up until flowering. So if that's a hundred to 120, 140 days, there's certainly the capacity for the roots to be growing with wheat, down to that 1.2, 1.4. So I find that, in a way, the crop will still push its roots down, but the wheat crop's smart enough or grows, in a way, to the environment that it'll have the root system in place, but it won't deplete those moisture resources.

Dale Boyd:
It'll actually preserve them and use water from the easiest source point, which is in that top horizon. But then once it's depleted, the root systems in place for them to pick up and obtain that deeper water.

Ethan Berry:

Our understanding of the importance of conserving summer rainfall has drastically increased since the installation of soil moisture probes.

Dale Boyd:

We've learnt a lot about it and learnt that it plays such an important part in the dryland crop production in Victoria. And we haven't been able to do this unless we've had those probes in place, recording that deep moisture, undisturbed. And now 10 years of data, we can actually see not only summer rain events, but also that carry over of moisture if the crop hasn't utilized everything from the previous spring. Seasonal variability, it's something we're dealing with. And now we know, with the control of summer weeds, if we get the summer storms and this season in central Victoria there's been two big rain events, one in January, one in March. Three inches the first rain, two inches the second one, and pretty much nothing in between. So that might be what we're dealing with in the future, long periods of dry, but storms and maybe extreme storms.

Dale Boyd:

And when they deposit that amount of rain over a shorter period of time, providing you got your soils in the right state of health, the infiltration can be great. And when they got infiltration that's moving down past 30 centimeters and into that sensor zone, we actually know how deep it's got. And we can find that, with summer weed control, moisture below 30 centimeters appears to be pretty stable, to be conserved, and then be able to be hopefully utilized for that winter crop that's been sown in the autumn. We also know that if there's moisture in that horizon. It's a lot easier for it to be linked into with those potential breaking autumn rains or those autumn rains or those early winter rains. And that's the key to crop production is, if you've got existing residual moisture, get it linked up as quick as you can.

Dale Boyd:

We can observe that with the moisture probes. And then once it's all linked up, providing you can meet all the requirements that the plant has in terms of sprays, nutrition, insects and pest control, the moisture is there for it to grow and develop and grow on. In terms of that residual carry over moisture, we've also found that grain farmers are very good at growing grain, but they've been able to adapt to, whether it's fodder markets or just the seasonal variability, that they've actually incorporated fodder into their production systems. And so they can actually look at what their moisture levels are like. If the crops out of moisture but it's got an amount of biomass that warrants cutting it for hay, and there's fodder markets that are prepared to pay for a reasonable price for hay, it's so much easier, or it's more comfortable for those farmers to flick the switch and say, this is no longer a grain crop.

Dale Boyd:

I'm going to cut it and we're going to rake and bale it and put it into hay and salvage something out of the season, potentially make some good money out of it, if the price is right. But that's just an informed decision that we've been able to make on the back of having that understanding of what the moisture status is from the moisture probes. So it's really good. Because I can think back in the millennium drought, we were doing lots of dry matter cuts, and we were trying to get an idea of what the biomass was of the crop. And we were just assuming that, down below, it was dry, but we only had part of the puzzle.

Dale Boyd:

Whereas now we've got a good indicator of what the soil moisture status is. I think we've got a greater understanding of what biomass and how that's going to relate to hay production. We can still do the cuts, but we've probably cut enough hay and can look at height and densities that we probably know what yield could potentially be. So it's really filled in part of that piece of the missing puzzle that I certainly wish we had in those millennium drought years.

Jemma Pearl:

Being able to see the data online almost in real time, enables you to correlate changes in soil moisture with certain events.

Dale Boyd:

I can tell by the probe data how the crop was using water. And I can almost tell the farmer, to the hour, that he's mown across that monitoring point, because all of a sudden the plant water usage has dramatically changed, or it's just ceased because the leaf areas being taken away. And not that I'm watching it every day, but I might look back and go, a week ago something's dramatically happened there.

Dale Boyd:

I know it was a fodder crop. You send him a text and you get the reply, it's been dropped. It's on the ground. It's curing. So that's been providing some great insights because it's been dedicated fodder crop, had moisture in the profile, you can actually conserve quite a lot of moisture for the following crop by stopping that plant water use during that October period when the fodder is down, drying and curing in preparation for baling. Because it's a peak water requirement for grain crops during October. End of flowering, into grain fill, it'll consume water to achieve those key critical growth points. And if you've got nothing there growing, it's all conserved. And it's a critical component that can then be utilized in the next year, the following year.

Dale Boyd:

And we've certainly observed the crops following hay to be quite good yielding. And now we can put the numbers to it, of why that's actually occurring.

Ethan Berry:

The effect that crop type has on water use and carry-over moisture is something the soil moisture monitoring network has been able to observe, which helps for next seasons planning.

Dale Boyd:

With those break crops, following those, the crops have yielded better. And now we can attribute that those pulse crops don't have the moisture requirements that a cereal or a canola crop would have. So finding that that pulse crop, whether it's lentils, peas. We're learning heaps about them, that they're not consuming as much water at times. They're still yielding quite well, but that carry over benefit is certainly paying dividends and well-worth, in those circumstances, incorporating or having that crop rotation that has the break crops in them, because they do have that benefit the next year.

Jemma Pearl:

With a network that has been around for more than a decade, there sure have been some things that people can learn from when implementing their own system.

Dale Boyd:

Terms of that initial strategy of putting down a probe and the first sensor at 30 centimeters, measuring down to a meter, still standing up quite well, but you probably don't need to measure and have that first sensor at 30 centimeters. Probably at 20 centimeters is fine. The probe length come as 40 centimeters, 80, and 1.2 meters. And there's certainly environments that have got better soil types, no soil constraints, and have got the rainfall that allow movement of water in the better seasons down past a meter. And we've also learnt heaps about the way crops grow, the way they develop root systems to extract that deeper moisture.

Dale Boyd:

We've found that that's such a critical component to achieving better water use efficiencies when you've got the moisture you can draw from in spring, because generally in those medium low rainfall zones, spring rainfall was not meeting the crop water requirements. So it's so important to capture those bits of data and down to a depth. So had my time, again, on what the new strategy would be. Probably measure from 20 centimeters down past a meter. And maybe look at that 1.2 meter moisture probe if you're in that right environment with those high yield potentials.

Dale Boyd:

People looking to consider putting in a moisture probe, for starters you're looking to identify the ideal reference point on your farm, as it's a point source measurement, it's not measuring a great amount of soil. So it's so important that the soil type that you look to identify has some good coverage across that paddock. And hopefully it's got a proportion of that soil that goes across your farm, so you've got that reference point that can be utilized for a number of scenarios on your farm.

Dale Boyd:

So a rain gauge is essential to be connected up to that telemetry and that logger. It plays great insights into, not only the distribution of rain that can vary across blocks to blocks, but also what infiltration can be attributed to rain. And then, while you've got a rain gauge, the logger has got a fair component of the cost to it. You could also certainly consider putting on a full weather station to collect not only rain but weather temp and humidity. So they're all really important. There's a number of service providers displaying or using their own platforms to display data these days. So you'd want to ensure that you're comfortable with the way the data's being displayed on those platforms. That it's easy to understand, but it's also providing enough detail. So it's a bit of a fine line of balance there, but you just want to make sure that you can understand the data and have it shareable, that you can certainly link in your agronomist or your advisor.

Dale Boyd:

They're always keen to understand the seasonal conditions as much as the farmers, because they're providing that advice to support crop production. Backup services is a critical component, with installation. That's also so important. I've installed some, but I generally like to get the service provider to do the install. I pick the site, but they do the pilot hole, insert the probe, do the slurry, and then connect up the cable. The probe, move it away from the fence line where there could be a weed burden, or just trying to make that site as representative as possible. And have it at a depth, that top of the sensor, that you can safely sow over the top. So you've got a plant population that's consistent with the rest of the paddock. And then just to be aware of what the short and long-term costs are in terms of data transmission, hosting the data and how you access it.

Dale Boyd:

So there can be some variations in that. So it's just good to be aware of it. And the other thing is that probably just have some way of validating the data. So coring tubes is what I've used. So if you've got some capacity to, not only collect data and examine it, but validate it, you got to fast-track your knowledge of what it means so much quicker.

Jemma Pearl:

Given that the Agriculture Victoria soil moisture network is publicly funded, everyone has the opportunity to check out the data collected and the analysis Dale puts on that data.

Dale Boyd:

There's certainly a lot more information on the webpages that we've got to display data, extensionaus.com.au/soilmoisturemonitoring, all in one word, is a great site that we're looking to display simply. Soil moisture in terms of the speedos, but I've also been able to identify, with each sensor, what its water holding capacity is. So we can actually break it down to each sensor to what capacity or percentage of moisture it's got.
Dale Boyd:

So that's a good page to look up to show what the benefits can display. But also on that page, we've got case studies where we've interviewed some of the host farmers and they've explained how they've used the probes and the benefits they provided to their businesses. And we also provide these interpretations and these newsletter updates on a monthly basis. So that's certainly a way of obtaining those newsletter links, and certainly would encourage a subscription to the newsletter. If this is of interest to you and you'd like to find out more, we can get that distributed to you on a monthly basis with the update to the seasonal conditions, which just vary year to year, season to season, and month to month.

Ethan Berry:

The website Dale just mentioned can be found in the show notes, as well as the link to subscribe to the cropping and pasture soil moisture monitoring newsletters.

We greatly appreciate Dale’s willingness to spend time with us in this episode to explain the importance of soil moisture monitoring technology.

You can find more helpful links in the show notes and you can get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcast. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 4: Not flying blind with weather, seasonal forecast and climate change modelling

Ethan:

This is My Rain Gauge is Busted, a podcast produced by Agriculture Victoria. I’m Ethan, and here we talk about all things climate and farming.

In this episode we talk to The Break’s fearless leader, Graeme Anderson, about the difference between weather forecasts, seasonal forecasts and climate change models.

There can be a lot of mystery behind models and forecasts, so we are going to get that demystified today. Jemma is going to take it from here.

Jemma:

Weather, seasonal forecasts and climate change are all very important to the current and future prosperity of agriculture in Australia.

And while the three different forecasts and models are similar, there are clear differences in what they are, how they are calculated and what they can be used for.

This is a topic close to Graeme’s heart and something he has been presenting on at workshops, field days and conferences for many years.

Graeme:
Yeah, well I guess for agriculture because agriculture and farmers are running their business, out in the weather. Understanding weather and forecasts and seasonal predictions and climate change are all really important but I guess one of the things when we talk to a lot of farmers, there's no shortage of confusion around trying to understand the different weather forecasts, the models, which ones do you trust and a common question we often get is, "Listen, if they're having trouble forecasting the weather beyond the next six or seven days then how the heck can they try and pretend they can predict the weather in 30 or 50 years’ time with climate change?"

Graeme:
So, I guess we've got a bit of a story to try and talk through the different components of what underpins weather forecasts, what they can and can't do. Then, talking about the seasonal forecast, which is looking past the weather forecasting into week two and three and into the next three months and then beyond three months what climate models can and can't do for looking at what's in store for the decades ahead.

Ethan:

The underlining thing for each is that they all rely on a model.

Graeme:
It's interesting. Talking about models and forecasts, it doesn't matter whether you're talking about weather forecasts or seasonal outlooks or climate change, they're all based on models and I know there's always a lot of discussion and jokes out about how much do you trust models but a key bit is knowing when to trust them and when not to and it's interesting, all farmers are used to using models. If you ask farmers about a particular paddock, so the front paddock and saying, "what sort of yield might you be expecting this year?" Their head will automatically bring up a model and they'll say, "I think we're on track for about a four ton per hectare crop," and you'll go, "gee, what are you basing that on?", and their model, they say, "well, it's made up of the historical. I know what we've grown there in the past. I know how much rain we've had. I know that we've got wheat in there this year and I know that everything's on track and about four ton is what we're on track for."

Graeme:
So, there's a lot of data that a farmer might call upon to be confident about, "yeah, we're on track for four ton per hectare." But then there's this whole bit about, well what don't you know and that's about the farmer says, "well, I don't quite know about what the finishing rainfall's going to be. I don't know if we might get a frost or I don't know if the neighbours’ sheep might get in." Those things aren't in the model. I'm just saying that, "how things are looking at the minute we should get four tons per hectare."

Ethan:

How the output of the model is communicated and what the model is able to tell us, is what makes them different.

Graeme:
One of the things when talking about forecasts of any sort is whether they're deterministic or probabilistic but really forecasting the future is a bit of a mug's game. Lots of people pretend to do it but no one really knows exactly how the future will play out and that's not just the story with weather and seasonal forecast but when you talk about the markets or the economy or what will trade prices or product prices be in the next three, six months. Lots of people are offering all sorts of commentary but really no one knows for sure what will happen in future but we're also not flying blind either and that's where modelling, understanding what's happened in the past and having all these forecast tools come into play.

Jemma:

You may have heard Graeme using the strange terms of deterministic and probabilistic. A deterministic forecast is one where the model is either run once and the answer is X or the model is run multiple times and the average of those models is answer. This communication is different to a probabilistic forecast, where the model is run multiple times and the outcomes are grouped and given a probability based on the number of times that group occurred.

Graeme:
So, the deterministic bit is just really about just saying, "this is what we think is going to happen with the weather." From a forecasting point of view, when you're looking at the weather for the next few days there's a higher confidence.

Graeme:
So, what they use is pretty complicated computer models nowadays, which do an amazing job because the computer power is getting so much bigger and our forecasts. There's so much more data being collected in terms of observations of weather and satellite imagery showing how weather phenomena is unfolding. All of those lead to an improvement in our weather forecast. So, if you went back to the '80s, a three day forecast was considered probably as far as you'd trust it and here we are 40 years later, we've got six, seven day forecasts, which on the whole are pretty good.

Graeme:
But one of the things to understand is how do these models work and when can we trust them and when can't we because they don't always get it right. So, one of the things about deterministic models is often what they referred to, it's really just talking about that weather in the next three to seven days and one of the key bits is this, just saying well it's deterministic because they're saying, "we're pretty sure we know what's going to happen," but I guess it gets a bit more complicated because when we look at different forecasts for the weather, there might be a bunch of models that are saying, "yes, it's going to be fine tomorrow and a top of x degrees but there is some rain brewing on the third day perhaps," and it's really interesting now and especially with farmers who have got lots of different apps on their phones or websites that can look at.

Graeme:
Day one is a lot more accurate than the forecast for day seven but the key bit to really be careful of weather forecasts is that there's some big weather events that the models can diverge so there can be a bigger range of things that happen and that uncertainty's really important.

Graeme:
And also, when you have thunder stormy weather ... So, the forecast might predict that okay, in three days time there's going to be predicted thunder stormy weather but they have no idea of knowing exactly where those thunderstorm cells are going to appear. So, that might only happen an hour or two beforehand and often in a thunderstorm that can make the difference between whether you miss it completely versus someone a couple of farms away might get 70 or 80 millimetres (mm) of rainfall. So, if there's things like thunder storminess in the forecast then that's a key question to say that well, the forecasters really don't know. Anything could happen.

Graeme:
There's actually a number of forecast providers and weather models out there and often I see this and sometimes the Bureau do a good job of this, the Bureau of Meteorology. There might be an extreme weather event brewing and they might up actually three separate forecast models showing how for this big weather event there's actually a lot of rain coming but depending on if you look at the Australian ACCESS weather forecast model, it'll say the rain's going to fall out here and how much it is but then the United States has a GFS forecast model and it might actually be suggesting the format of that weather event might be in a slightly different position and there's also the common European model, which is the ECMWF model often used in seven day forecasts and often they'll put a map of those three just showing how yes, there's a big weather event brewing but each of these forecasts actually has a different amount of rain. So, if you're a farmer it might mean the difference between whether you might get 5 or 10 mm or whether you might get 100 mm.

Graeme:
So, each of these models is trying to do it's best to work out where this weather event's going to unfold but none of them actually know exactly what will happen and so, that's where it's really important to know who's weather forecasts are you looking at and sometimes knowing the uncertainty in a weather forecast is just as important as knowing the amount of rain that might be being predicted.

Graeme:
If you're on your phone just looking at one model and it's saying 80 mm and then your neighbours’ looking at a phone app and it's from a completely different model and it's saying five mm what tends to happen is they all blame the Bureau of Meteorology if the rain we get doesn't match what's on the forecast but for probably half the farmers I speak to and then we look at, well, what model are you using for your forecast? At least half of them aren't coming from the Bureau of Meteorology. They're models that are coming from somewhere else and that's not necessarily a bad thing but it's just important to know who's forecast are you looking at, which is a pretty key bit and also, some of these tools that just compare the range of models can be pretty useful because it's telling you about the actual wider level of confidence about what rainfall might be in store.

Jemma:

Forecasting is a serious scientific and mathematic exercise, so it is very important to be following credible sources.

Graeme:
There's a lot of people putting illegitimate stuff out there. No one can predict the future. That's the key bit. It's amazing what bloody weather forecasts can do but also they're not infallible and you see too, there's a lot of stuff happening where people got their weather station and they can get some program that'll give them a 30 day forecast based on their weather station and they think that this is just a huge breakthrough and you go, no. It's just some model and they've got no idea what's going to happen after seven days but people are taking this false face, so it's important to try to get it about, listen guys, anyone telling you they've got you a 20 day forecast, it's for weather.

Jemma:

Probablistic forecasts can trip many people up, but it is the only credible way to predict out past a weather forecast.

Graeme:
Yeah, well see weather forecasts pretty good out to seven days and as you head out things get a lot more less certain and that's where we move into the multi week and seasonal forecasts and where we often talk a lot more about probabilistic forecast because basically we're moving out into the outer reaches of the confidence levels of the models and rather than being able to say, "listen, in 30 days we know it'll be exactly this temperature and there'll be rain at 3:00 pm in the afternoon." The models actually cannot do that, and I do know there are some websites that pretend they can do that but they're just really pulling people's leg. Once we go past that seven, eight, nine days of the weather forecast what happens on any one day is less known. We're really just looking at longer term climatology.

Graeme:
So, when they're talking about anything beyond the weather forecasts and adding to week two, three and the next three months they run the weather models but they don't just run them once. They might run them 100 times and depending on how that ocean pattern's set up and if it's sending more moisture or more cloud or less. Basically, the models just calculate well, how much rainfall fell at the different parts across Australia. Sometimes there's a complete spread of those forecasts so you might see that of the 100 runs, 50 per cent of the models were wetter than average and 50 per cent of the model runs were drier than average and that's where you're seeing the full spectrum of things are on offer and often that's what they might call a neutral forecast where they're saying, "there's no strong driver there that's really skewing the forecast one way or another," so pretty well you've got anything to expect.

Graeme:
It could be from decile one, all the way through to decile 10, which is the wettest 10 per cent. It's sort of a real lottery but if you introduced into that that oh, now there's a big La Nina event, it's really warm sea surface temperatures to Australia's north. There's lots of cloud or there's a negative Indian Ocean Dipole, which again, send lots of extra moisture our way. If you run the climate models over that for the next three months it wouldn't be surprising to see 80 per cent of the model runs say, "oh, now you're going to be wetter than average because we've got this extra moisture feed feeding in."

Graeme:
A big challenge as with all forecasting is understanding the language and what's meant by the person saying the term versus how we hear it and often when someone sees, especially with some of the seasonal forecasts where they might say there's a 50 per cent probability of more than average rainfall and that's actually the same as a 50 per cent chance of less than average rainfall and people think, oh, well we should expect average but often that can mean the full range of rainfall outcomes are in there from very dry to wet. It's just that half of the model runs were wetter and half of the model runs were drier. So, you shouldn't really bank on average in that situation.

Graeme:
There's some good projects underway. I know the Forewarned Forearmed project that industry Australian, sort of industry, the managing climate variability program and the Bureau of Meteorology are working on to really improve how they talk about those forecasts. Different things are coming like, farmers are more worried about whether it's going to be really dry like in the driest decile one or two, which is the driest 20 per cent of years, the risk of that. So, they're looking at how do you do the forecast of trying to show, have the odds changed for being in that dry zone if it's at normal or have we doubled our chance of being in decile one, two?

Graeme:
So, hopefully some of the language behind these forecasts is going to get a bit better, a lot more meaningful because there's a big risk if people misinterpret a forecast and make a decision from it then it could do harm.

Ethan:

The one that many people get stuck on is climate change modelling.

Graeme:
People say if you can't forecast past seven days then how can you tell me that the year 2050's going to be warmer? What's really interesting is there are parts of climate change that we're actually more confident about than we are about the weather at a particular site in 10 days time. So, part of it is just how understanding weather and the climate works but one of the key bits with ... we know we've got lots of variability and in our last few hundred years of rainfall history and even longer term rainfall records, we've got all of that but part of the issue with climate change is really back to do with the greenhouse gas story.

Graeme:
In most places we've seen over the last, especially last 50 and 100 years, increasing temperatures. 90 per cent of that heat's gone into the oceans and we're at the early phases of that. So, the whole story of climate change is, well if we keep adding more emissions then we're really going to start to increase the amount of heat but also then starts to have questions into, well how does that effect our longer term variability? We know what good old-fashioned variability and what our rainfall records have done in the past but how might that change in a world that's a lot warmer? So, that's where a lot of the climate change modelling comes in to try and look at what happens with that.

Graeme:
Certainly, when you look at the last 50 years and changes in temperatures and weather, you can only replicate the increases in temperatures when you include increasing the greenhouse gases in the climate models. So, there's been a lot of work done on that end. I guess that's why there's all this discussion and effort now going into making sure we choose a low emissions future.

Graeme:
The bit about the climate change stuff is we know if you warm up the whole planet basically, the tropics is the hottest part of the planet, the tropics along the equator so if you warm everything up, the tropics expands either side of the equator and it sort of nudges weather patterns closer towards the poles.

Graeme:
So, from southern Australia's point of view, if you warm up the world, the westerlies and they bring all of our south westerly and cold frontal weather along southern Australia, that all just gets nudged 500 kilometres to the south for every certain amount of warming. That's just the physics of how the planet and the weather systems work. So, a lot of the climate change models, they're confident that we're going to have increased heat, we're confident that it shifts weather patterns pole wards, we're confident that actually when you warm up the atmosphere it means it rains heavier so it increases rainfall intensity but there's also lots of things that the climate change models aren't sure about and that's why there's a range of models in terms of some places predict a much greater amount of drying than others. Some predict greater heat extremes than others and some really don't tell us a lot about what will happen to core modes of variability such as the El Nino Southern Oscillation and how the Indian Ocean pattern might change.

Graeme:
In a world of eight billion people when you add climate change and the physics and how that effects good old fashioned variability, it just does add and puts a lot of extra pressure on our systems in terms of what sort of intensity of rainfall we've got to be able to manage for peak flows, how we manage for bigger droughts, how do we manage for increasingly bigger heatwaves and those sort of things. So, that's part of it.

Graeme:
We're always going to have seasonal variability in there but in a warmer world the dynamics of some of this changes quite a bit. I guess part of the question though is that while the climate change and the modelling and the science is confident around some areas of it, there's a lot of uncertainty there, especially about there could be some bigger surprises in there that we haven't really discovered yet. So, from a practical point of view in farming we've just got to be prepared to make sure we're good at reading weather forecasts, make sure we understand what's in seasonal forecasts and then taking what lessons we can out of recent trends and understanding what might be coming with climate change projections and then improving that in how we set up our farm businesses.

Graeme:
So, we can see a lot of great stuff that farmers are doing to basically get better set up to handle that variability.

Ethan:

While all of this sounds very big picture, future focused, Graeme explains that farmers are doing a great job of setting up their business’ to deal with variability into the future.

Graeme:

Agriculture's done a great job growing a lot of food and fibre amidst some pretty tricky seasons in the last 20 years but when everything goes right we can grow more food and fibre than ever but within 12 months we can be having an absolutely horrible run of seasons or weather event, so part of it's just trying to set up a system for how do we cope with that greater variability.

Graeme:
I guess one of the key bits about this is that all of these forecasts, whether it's the weather or the seasonal outlooks or the climate projects, they're just ... It's important to understand enough about which bits are we confident in? Which bits aren't we? And then the key bit is that it's in the role of farmers and us as humans of making decisions today that leave us better off in future. So, whether that's doing something today that would differently because of the weather forecast or doing something today because we're saying, "we might need bigger fodder storage facilities or better water storage because of climate change."

Graeme:
They're the things that we've got under our control and we see lots of great stuff that farmers are doing. I know talking to farmers when it comes to forecasts and even seasonal forecasts, they say, "we never rely solely on just the forecast. We know the forecast is something we take a look at but if we're trying to work at whether we offload some livestock, we're looking at things like how our current carrying numbers, how much soil moisture have we got in the ground, how much extra fodder have we got, what's the current growth rate of pastures," and all of those things are knowable, things that can be known so you should be looking at those things as the majority of the decision and then just saying, "well, so what's the forecast saying? Is it going to actually help bring this decision forward or is it helping or is it hindering?" So, that's the important bit is that these forecasts, they have a role but they're really only part of a wider decision of where you're trying to use active measurables to base it on.

Graeme:
Farmers do a great job managing all that and when we look at what the secrets are for the farm businesses that are handling modern day variability really well we see there's lots of great innovation and new research and genetics and things that are applied on farms. So, keeping the flow of innovation coming's really important. We see lots of onfarm infrastructure that's being added that makes farms better set up to cope with those varying seasons. That's been really important and not just on farm but also regional infrastructure like pipeline networks and transport and communications infrastructure.

Graeme:
One of the things really important is to be being profitable so making sure our markets are open and good biosecurity is really important because what we've seen is if the product what you are growing, if you're getting paid for it that gives you enough money to be able to make the changes on farm to be better set up for variability. It's very hard coping with increased variability if your core market fundamentals are pretty poor. So, still got to be in the main game of being profitable.

Graeme:
The other key bit is farm planning. We see great work done on trying to make sure there's good land management because most of the sort of damage is done when dealing with really wet or really dry periods. That's when overgrazing and soil damage and all that stuff can happen. Business management, we're seeing farms making great progress on improving how they manage that financial variability. So, how do you make the most of the good years and then have some of that up your sleeve for when things are tough? That business stuff is getting more and more important.

Graeme:
Farms that are really going places, they're just really good at surrounding themselves with the right people and networks. So, they're getting lots of good information, lots of discussions, they're involved with local farm groups. All of that stuff really helps you be well set up, well informed to take advantage of opportunities and support one another as we work our way through all of this.

Jemma:

But as always Graeme cautions where you get advice from, making sure it is scientifically based and has a good grounding with current information on hand.

Graeme:
Often the newspaper is full of all these experts. The same with shares and all that stuff. They're all experts about explaining what happened last week.

Graeme:
And the difference is when you're more confident is when you understand more of the fundamentals and you're getting access to some trusted advice to say, okay, this is why I think the market's going to go up because here's some good fundamentals and reasons why and I can start to see that trend there. I understand that or I think the price of x is going to go up because look, there's a big shortfall here and inventories are down so I can see that that's holding up good. So, when you've got more of that data and understanding behind it from a trusted source then you've actually got a bit more to go, yeah, I think I do trust this forecast. My prices are going to go up. There are other times people are offering it and if you can't see any reasoning why then they're just making it up.

Graeme:
Those drivers, when they're really active, when the El Nino drier phase is on or IOD positive phase or when they both team up, like the big droughts of '06 and '82, farmers remember them and if they're getting picked up in the forecast model then there's times when you got a stronger confidence in that outlook but same as the 2016 Indian Ocean Dipole, when it was wetter and all the models are onto it and you can see it happening then you've got a much stronger confidence in the outlook but what frustrates people is some years there's nothing to go on. And that's part of the dark art of when to trust them a bit more is saying, when is this forecast telling me something that really is going to, that I need to take more notice of and when do I just ignore it and plan for anything?

Jemma:

We thank Graeme for delving deeper into the dark art for us and giving us some tips and tricks to understand when to and not to be looking at a forecast, be that a weather, seasonal or climate forecast.

Ethan:

We hope this episode gives you some ideas on how you can mitigate some of the variability in your work and helped to show what forecasts can do and what they can’t do.

We have included some helpful information sources in the show notes, and as always you can get in contact with us at the.break@agriculture.vic.gov.au. See you next time.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcasts. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 3: La Niña does not equal flood

Ethan:

This is My Rain Gauge is Busted, a podcast produced by Agriculture Victoria. I’m Ethan Berry, and here we talk about all things climate and farming.

In this episode we talk to the man behind The Break and The Very Fast Break – Dale Grey, about the La Niña climate driver.

Dale provides regular seasonal updates and outlooks for farmers in and around Victoria, and is here to give a sense of what La Niña means – and crucially what it doesn’t mean – for farmers in south eastern Australia.

But first Jemma Pearl is going to explain why we are interested in this driver.

Jemma:

No doubt you have heard the terms La Niña and El Niño. And while these drivers are typically associated with wetter and drier conditions respectively, this is not always the case.

On average we would expect to see a La Niña one in every four years, with a El Niño and two neutral years completing the bunch. In the last hundred years there have been somewhere between 25 and 30 La Niñas, so roughly working out to be a quarter of the time.

We asked Dale to take us through some of those years.

Dale Grey:
Yes, there's been periods in the past that people would remember, that have been classically really wet. And some of those classic La Niña years, that people might have heard of, were the Olympic year in Melbourne, which was 1956, which was very wet in Northern Victoria. And then the next one that was iconically really wet was 1974. So some more than 20 years there onwards. We had to go a lot more years on until we got to 2010, where we then got to the one in most recent memory, which was very, very wet as well.

Dale Grey:
There's been obviously plenty of other La Niña's in between those times, some of them have been wet, some of them have been normal, and some of them have been actually quite dry. Like, good old 1998, one of the totally rubbish ones, in fact. And then you've got a double La Niña at 2007 and 2008. And 2007, in particular, was absolutely very ordinary season.

Ethan:

To really understand what a La Niña is, we need to explain how they form and what are the key characteristics of a La Niña event.

Dale:

So the scientists, when they're identifying La Niñas, and El Ninos, for that matter, are looking at an area of the ocean in the center of the Pacific that they call Nino 3.4 and it covers sort of some 30 to 40 degrees of longitude, and it covers plus or minus five degrees of latitude, north and south of the equator. So rather than just dipping a temperature probe in one spot in the middle of the Pacific and going, "Oh, it's an El Nino", they're covering hundreds of thousands of square kilometers and getting the temperature of that from satellite and the buoy readings to give us the measurement of what the temperature is. Now, they look at other regions as well, such as Nino three which is a slight shift of that box more towards the Americas. And then there's Nino one, two, and there's Nino four as well.

Dale:

But what's interesting is that the positioning of temperature changes in the Nino 3.4, what happens in that box in particular seems to have a greater correlation with rainfall changes in Eastern Australia. And El Ninos and La Niñas are phenomena that form along the equator from the Americas out into that Nino 3.4 box. But the strength of the temperature changes that are occurring in that Nino 3.4 area tend to have a greater influence on us. But what’s more important is how the temperature changes around Australia and to our North.

Dale:

And so, La Niñas are classically where the ocean along the equator from the Americas out to the middle of the Pacific is cooler by some sort of 0.8 degrees. The Americans use a threshold of 0.5 degrees, much lower than us, so they call a lot of very weak La Niñas which don't do much. The Australian Bureau has a threshold of 0.8, so it's a little bit more solid. Once you get to 0.8, you can be more guaranteed that something's probably actually happening as opposed to a little flash in the pan that then dies away. So a La Niña is a 0.8 degree cooling of that area of the ocean. It's not even one degree, it's such a tiny little temperature, and yet it makes a massive difference to the world's climate.

Jemma:

The Pacific trade winds are especially important in a La Niña. In their normal state they blow in an easterly direction from South America through to Papua New Guinea. But as Dale explains, its when the trade winds change that interesting things happen.

Dale:

When we have a La Niña, the trade winds are accentuated along the equator, really from at least halfway along the equator and Nino 3.4, right across through to the Western Pacific to near Papua New Guinea. And those trade winds are blowing a lot stronger from the east. And as a result of that, they are physically pushing the water in that area further to the west and to the north of Australia. And while those trade winds are blowing stronger, they're holding warmer water to the north of Australia and not letting it go back to where it wants to be out in the central Pacific near the International Date Line.

But at those trade winds are all pervasive. They can very strongly push water in a different direction or in the more accentuated direction in the case of La Niña, and hold it there. And so while those trade winds are blowing stronger, they're holding the warm moisture source to the north of Australia there from some three, four, five, six months period, as an increased moisture source.

Of course, if the trade winds blow in the opposite direction, which they sometimes do as a result of the Madden-Julian oscillation or a cyclone in the area or just the random tropical weather, that can put a reversing force on the ocean and send it back in the other way.

And not only does it push the ocean water at the surface over to the east, but it puts a downward force on the ocean as well. And it forces some of that warmer water at the surface under the ocean. And it sends it on its way over towards South America. This has got a fancy term called a Kelvin wave. And the Kelvin wave of warmer water, in this case, is really the turn-off key for La Niña. La Niña would just keep going and going and going if it wasn't for this sort of process for where you can get a reversal of the trade winds, send some warm water underneath, send it over towards the east and nullify the cold water which sort of decreases that pent up emotion for coldness in the deepness of the Pacific, and brings you back more to the neutral condition again.

Jemma:

The middle of the Pacific Ocean is very far away from Australia, so you are probably thinking, how can that water be affecting us?

Dale:

And how it affects Australia's climate is that that cold area of water in the central Pacific influences warmer water to the North of Australia. And warmer water is critical for evaporating more moisture into the atmosphere, and as a result of that, if you get the right triggers, you can drag some of that extra moisture down. And so what was interesting in the summer of 2010 was that the sea surface temperatures were a record level of warmth to the north of Australia. And by definition, that had to be evaporating a record amount of moisture into the atmosphere. And perhaps not unsurprisingly, given the right triggers, areas of Eastern Australia somewhere got record amounts of rainfall. There's very good correlations between all three of those things, the ocean temperature, the evaporation and the rainfall.

Ethan:

The area where there is warmer than normal water also greatly affects the position of cloud.

Dale:

Well, there's normally a big, massive cloud at what we call the Intertropical Convergence Zone, which is at the junction of the equator and the international date line, which is not quite in the middle of the Pacific. It's a little bit to the west of the middle of the Pacific. And that's where the very warmest part of the Pacific Ocean normally is. And that's where cloud is forming off that warm ocean and it's causing lower pressure in that area as well. Now, when we have the La Niña condition, which is just an accentuation of the normal process in the Pacific, the trade winds are blowing way stronger from east to west. They're pushing warm water to the north of Australia. And that low pressure uplift zone of moisture and evaporation forming cloud shifts to the north of Australia. So not only is the ocean surface warmer, it's evaporating more and it's condensing and forming more cloud to the north of Australia. And so, once again, that's an indicator of the moisture source being turned on and better.

Jemma:

One of the indicators discussed when talking about La Niña is the Southern Oscillation Index or the SOI for short. This has to do with pressure patterns, and is some times not a great indication of climate driver activity.

Dale:

So, this accentuation of winds and lowering pressure to the north of Australia and increasing cloud also changes the pressure patterns right around the equator such as we've got lower pressure to the north of Australia. Lower pressure to the north of Australia is like pushing water downhill down towards the southern regions. Anytime you've got higher pressure in the tropics, it's like pushing water uphill. So, not only have you got a better moisture source up there in the north, but when the pressure is lower, it's just easier to get the moisture down as well. So, the indicator that we use to measure the pressure is called the Southern Oscillation Index. And it's a pretty blunt stick. It's just two pressure readings, one at Darwin and one at Tahiti out in the central southern Pacific.

And so when we've got a La Niña, that warm water to the north of Australia is evaporating more moisture, there's air masses going up so the pressure is lower in that area. And out in the central Pacific where the water is cold, there's no cloud, there's a lot less going on there, and the air mass is actually descending over the top of that region and causing much higher pressure. So the SOI is positive when we have La Niña-like conditions, when you've got lower pressure at Darwin and higher pressure at Tahiti. Now, the SOI jumps around all over the place. It's measured daily, it's affected by all kinds of tropical weather. Particularly over summer where it's a fairly erratic thing to be looking at over summer because things like cyclones just dramatically affect the SOI.

But rather than looking at daily readings, you always to be looking at a 30-day reading of the SOI to sort of average out some of that weather stuff that's going on. And generally between values of plus or minus five, plus or minus seven, the Pacific and the El Nino and the La Niña and the pressure patterns there are deemed to be basically doing nothing, just bouncing around between normality. But once you get above plus or minus eight, and in the case of La Niña, above a value of plus eight, that normally would be deemed to be pressure conditions that are linked to La Niña. So we'd expect to have lower pressure at Darwin and higher pressure at Tahiti.

Dale:

So, we have a history in Australia of probably looking at the SOI a lot as the reading of La Niña, and El Nino, for that matter. But in reality, the SOI is a surrogate measure of what's going on out there. An actual El Nino or La Niña is measured out there in Nino 3.4. That's where it's going on. But to get a proper coupled La Niña, you need the SOI, the pressure patterns to be linked up and doing the right things as well. So the critical thing is always look at the centre of the Pacific Ocean to see what's going on there, then look at the SOI. And if the two of them are saying the right things and they're both singing from the La Niña hymn sheet, well, it's time to prick your ears up.

Ethan:

Dale mentioned coupled events and coupled La Niñas, but what does that mean?

Dale:

Now, this all links to the principle of La Niñas and El Ninos, for that matter, that are coupled, versus uncoupled. Generally, when people are talking about La Niñas, they're talking about is the centre of the Pacific and Nino 3.4, is it colder than 0.8 degrees, than normal, is it colder? And if it is, people would say, "Well, that's La Niña-like temperature." But in terms of the response that we see. We need to see the trade winds blowing stronger. We need to see warmer water to the north of Australia. We need to see extra cloud forming in that area. And we'd expect to see lower pressure.

But sometimes you get what's called uncoupled ENSO events. And so you may have the ocean temperature in the middle of the Pacific desperately putting its hand up at, probably the front of the class, going, "I want to be a La Niña. In fact, I am one right now." And the atmosphere above saying, "I'm not having a bar of that at all." And the SOI just sitting there at normal, no actual cloud pattern formation. And in some respects, that's what we saw this year in the 2020 spring event where the La Niña was saying, "Yes, I want to be a La Niña out in the Pacific Ocean", but we didn't get any of those cloud and pressure patterns forming classically, like we'd expect. Which indicated that there was something up with this event that wasn't classically like we saw in 2010.

Dale:

So you get these uncoupled events and I think that's what leads to the fact that sometimes we have La Niñas that are La Niñas but they're not properly coupled, or the ocean's not that warm to the north of Australia, or perhaps we have another climate driver that's working against the La Niña. And that happened in 2007 and 2008, for that matter, which were both La Niña events according to the Pacific Ocean being cool enough in terms of the threshold. And perhaps even the pressure patterns being roughly right too. But 2007, for much of Victoria, was the second driest La Niña on record. And that's in people's recent memories.

So not only did we have the 2010-11 ones doing something, but we pretty recently had ones that were absolute fizzes of an event. And if they were in people's memories, that was probably not helping their belief that 2010 could come through with something. But it's always interesting as to how there's nearly always someone on the eastern coast of Australia who turns out to be wetter when you have La Niñas. It's just that it's always a different spot. Some years it's everybody, but most years it's not. Most years it's very spatially distributed. Some areas are wetter and some of them may in fact be drier in La Niña.

Ethan:

Over 2020 there was a lot of talk about the forming La Niña, but while it was similar to 2010, Dale explains that no two La Niña events are the same.

Dale:

the models were predicting a La Niña all year quite early on from sort of May onwards. It really didn't come together and sort of until September in terms of an actual fully functioning one. And then the rainfall started to pick up in October and November sort of patchily across Victoria.

And then we've had a La Niña over the whole of the summer. But the actual rainfall response, unlike 2010 where the whole state was much wetter over summer, this year the 2020/2021 La Niña over summer, it's been much more patchier in terms of where it's been wetter and where it hasn't.

Dale:

What was interesting in the 2010-11 summer was that as spring was out, and we're in spring looking at the summer predictions, a lot more models. There started to be a much stronger consensus for wetter for summer. And of course, that was a bit unusual because often La Niñas over summer are a bit hit and miss. The models were sort of predicting it to be wetter, much the same as they were for this year's event. And we started to see some very emphatic forecast from the models, which were predicting it to be much wetter, as opposed to be just a bit wetter. And that was a bit hard to believe too because we hadn't seen anything like that before. And yet, some of those models clearly were right. It was absolutely much wetter. And so that sort of gave us a bit of heart, I suppose, in future years that, when the ducks are lined up, the model in 2010-11 was really good at picking up that things were looking turned on for making rainfall and wetter indeed. And many areas had had record rainfall.

Dale:

So I think that this current La Niña that people were remembering the previous one and they were probably making some comparisons between the two. All events are different. No two are the same. But we did have a number of models that were making predictions like in 2010. And so I think it was probably prudent for people to be at least making some plans and being concerned for wetter. That hasn't really turned out to be the case in many parts of Victoria. So it's sort of this La Niña perhaps reverted back more to the statistical kind of things where La Niña's over summer and Victoria have historically a bit hit and miss. Now this one's certainly been the case.

Dale:

And the La Niña itself it was more weak to moderate. It wasn't a strong event by any stretch of the imagination. Which is interesting because it's often that people make a connection between the strength of El Nino or the strength of La Niña events and make correlations with potential strength of the rainfall response. In fact, if you look at the statistics, there's a very poor relationship with those. We've had very dry seasons in very weak El Ninos, and we've had very wet parts of Australia, like we did in the summer of 11-12 with quite weak La Niñas. So the actual strength of the event, which is measured by what's going on in the center of the Pacific Ocean is no great indicator of what the result might be.

Dale:

This is the nature of the way they form and behave. We very rarely see El Nino-La Niña behaviour in autumn. It's a phenomenon that normally develops during winter, normally appears in spring, and normally decays in summer. But every now and again, you get events that muck around in winter, they form in spring, and they are active over summer and then die in early autumn. Everything dies in autumn and then reverts back to normality, and then you start another season and something may or may not happen.

Dale:

If you were going to sort of put a rough figure on it for Victoria, about half of the La Niñas have been in the wettest third of records, so much wetter than normal. But you'd probably have about 30% of them that have been average. People wouldn't tend to complain about those. There's probably been 20% of them, I suppose, that have been in the driest third of records where people might be a bit sort of narky that the La Niña completely failed to fire.

So, I think it's interesting that when we read newspaper articles and we see the word La Niña, we'll often see the word flood appearing somewhere in the next 10 words. And likewise, drought with El Nino. But the reality is that that has never ever been the case. There is no perfect link between these phenomena and what actually happens.

If you just look at any historic record and rank it from lowest to highest, a third of the years are dry, and a third of them are average, and a third of them are wet. But La Niña spins at up to a 50% chance of being in the wetter end of things, but doesn't deny the fact that you might, in fact, have a lower chance, but not a non inconsequential one that it might actually be dry.

Ethan:

Many farming families and business’ have fantastic long term weather records, so you could look at how the rainfall results on your property line up with the different La Niña years.

Dale:

Well, the first place is the Australian Bureau of Meteorology. It has a fantastic list of previous La Niña years and it has some fantastic commentary about how they've performed and whether they were coupled or not. But we've done the hard work for you here at the break and we've taken that list, and we've put it into a website called the Local Climate Tool. And what that allows you to do is to interrogate those La Niña years and look at the rainfall that's happened at varying locations in southeastern Australia. And for that matter, you can see the other climate drivers there as well, but we're talking about La Niña.

Jemma:

As ever, Dale is a great source of seasonal climate information and its impacts on agriculture in south eastern Australia. We greatly appreciate Dale giving up his time and willingness to share his knowledge.

For more Dale commentary don’t forget to sign up to the Fast Break and Very Fast Break. The link is in the show notes.

Ethan:

Dale has shown us that no two La Nina events are the same and while it does spin up the odds sometimes they can still be pretty dry.

Dale has shown us that no two La Niña events are the same and while it does spin up the odds, sometimes they can still be pretty dry.

We hope that this episode has shed some light on the La Niña climate phenomenon and how it affects seasonal conditions in south eastern Australia.

You can find more helpful links in the show notes or get in contact with us at the.break@agriculture.vic.gov.au, for more information. Catch you next time.

Catch you next time.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcasts. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 2: Sea surface temperature, the measurement of ocean emotion

Ethan Berry:

This is My Rain Gauge Is Busted - a podcast produced by Agriculture Victoria. I'm Ethan Berry, and here we talk about all things climate and farming.

In this episode we are going to talk about sea surface temperatures and more specifically how the data is collected to create sea surface temperature maps.

Now, before you click away, I want to touch on how important that is because it might not sound very relevant, and you might be thinking “why dedicate a whole episode to sea surface temperature data”. But as Jemma explains, without sea surface temperature being checked all over the world by boats and buoys (and even a few fast swimmers), seasonal weather forecasting would be a whole lot more difficult. So, this information is incredibly useful for researchers and farmers alike, and is the basis that seasonal forecasting and modelling comes from.

Jemma Pearl:

I once heard someone ask that exact question. Why would we be interested in sea surface temperature? The answer was simply put, because we are surrounded by ocean.

What is happening in the oceans greatly affects what happens on land. We are particularly interested from an ocean temperature perspective of the areas that are 24 degrees Celsius or higher. Because at this temperature and above there are significant amounts of evaporation. That evaporation accounts for a vast proportion of the rain that falls on land.

When the temperature gets to 26.5 degrees Celsius and higher, formation of cyclones can occur.

While there are regions of the world oceans that we are more interested in, for example the Pacific and India Ocean, technology like buoys both floating and fixed, ships and ARGO floats are found almost everywhere and all have their own unique role.

Ethan Berry:

We recently had the opportunity to talk to Helen Beggs from the Bureau of Metrology, who in her own words is the Southern Hemisphere expert in satellite Sea Surface Temperature and is very passionate about what she does.

Helen Beggs:

I started at the Bureau in 2003. Prior to that, I was an oceanographer in Hobart at CSIRO. I went to sea a lot. I'd wintered twice in Antarctica. And then I did a PhD about the Antarctic sea ice zone and carbon air sea gas exchange over Antarctic ice zone. And then we moved to Melbourne and I was in IT for a couple of years, and I got a job at the bureau and I've been there ever since.

Jemma Pearl:

Sea surface temperature, commonly referred to as SST, has been collected for a long time, as we became more and more interested in how currents, temperature and wind affect fishing, sailing and of course the weather.

Helen Beggs:

Well they were doing it on various research expeditions, I guess. Darwin probably collected it, but it wasn't until 1853 that there was a meeting in Belgium where internationally the conference decided that they were going to try to accurately collect SST data from ships. And they started off with wooden buckets that they normally use on ships, but they were rather large. They discovered that if they tried to use some from steam ships, they might lose a crew member. So it was rather dangerous with such a large bucket.

So, once they started to use steam ships which was around 1850s to 1920s, they decided to use a canvas bucket which was rather smaller and they could hold onto it at the speed that the ships went at. After the 1920s, they use the canvas buckets until they were replaced by rubber insulated buckets in 1950s and 60s.

And in fact, for safety reasons, certainly, especially during World War II, they replaced the bucket readings. They started to replace them with the engine intakes because they didn't have to go on deck with a light and get shot at. So they wanted to use a thermometer at the water intake inside the ship.

So what they've had to do, the scientists who want to look at the climate record of SST, they've had to actually adjust the engine intake temperature data, because it's too warm and the buckets are at a more consistent depth as well because they're in the top metre or something of the ocean. They are cooler than the engine intake.

As the method of measuring the water temperatures changed over the years the scientists have had to account for that because they know that as you change the method that there may be biases, but certainly in more recent years we have far more accurate sensors of course.

Ethan Berry:

While ship data is only really collected from the shipping and travel routes around the world. Ships have remained an integral part sea temperature data collection, now with more high-tech equipment on board.

Helen Beggs:

In 2008, through the IMOS project, I started to instrument ships around Australia with hull contact temperature sensors and they are more accurate than the engine sensors because they're on the actual hull. So as long as it's a metal hull it equilibrates really quickly to the temperature of the water outside. And if you use a good contact, you can actually measure temperature pretty well and I discovered that the accuracy is equivalent to drifting buoys, which is really great. So, we now have quite a few of those around Australia.

The ships that send back data from say a cargo ships and ocean liners, ferries that sort of thing. They send it back every six hours, if it's got to be manually measured and transmitted. However, we also on some of those ships such as the spirit of Tasmania II, for example, across Bass Strait the Bureau has installed an automatic weather station on board, much like the ones that are on some farms and elsewhere around Australia, which are unmanned, which don't have to be touched by the crew onboard the ship, which is good. And they send back data every hour and that is processed at the Bureau, and then it's uploaded onto the GTS. So it's shared globally and that's really important. And those observations are generally more accurate because they aren't someone doesn't have to read the instruments manually and it's automatic and everything.

What is interesting is that the crew on the ships, they provide it unpaid. They do it as just altruistic reasons, but they, they obtain the weather forecast of course, on the ships and they provide data just as our farmers do too. There are lots of volunteer observers on farms just as there are on ships who have to take the readings every six hours and transmit them via a radio.

Another important source of data are the science vessels such as RV Investigator. And Aurora Australis, prior to it being sold and others like that, and vessels that are up in the tropics that study the Great Barrier Reef they send back data as well and we process the data and it's uploaded and shared.

So those are sort of the two types of ships, really the commercial vessels, which can be quite small ferries up to very large bulk carriers and also the science vessels, which can range in size.

Jemma Pearl:

The Global Telecommunication System, the GTS, is the global network that allows counties to share meteorological data and it is vital for Australian scientists and modellers as Helen explains this is the main way they receive satellite SST data.

Helen Beggs:

We rely on international satellite data for all our weather models. And if we didn't have that satellite data, we would not be able to predict the weather basically. And Australia owns and operates no weather satellite, unfortunately. So, we are totally dependent on the US, the Japanese, the Chinese, and ESA in Europe as well.

Helen Beggs:

It wasn't till IMOS started in 2007 that we started to share ocean data freely around Australia because prior to that people would just collect their own data on cruises, which were very expensive and they would hold onto it for two years. So, there was an embargo in fact, on it being available publicly for one to two years, which was rather frustrating. And certainly, if you had a buoy say a mooring, you kept hold of that data. It didn't get shared. And it's very expensive to collect that data. So, scientists didn't want to share it.

It is not cheap to have like a research cruise will cost you up to $50,000 a day. And that's just to pay for the vessel. Let alone actually have instruments on board and pay for the technical staff that you have to have on board. And the scientists who are really the cheap bit, but you've got to pay them and the crew.

Not all, but an awful lot of Australian ocean data from various agencies such as CSIRO and the Bureau, AIMS up in Queensland and the Navy is now provided. There's a portal that scientists and students and the public can go to, to download ocean data.

And it's all funded by IMOS, which is funded by NCRIS, which is the Australian Federal Government.

Ethan Berry:

Some of the important technology and infrastructure used to collect sea surface temperature data include buoys. These can be moored or drifting. Moored ones are attached to the bottom of the ocean and drifting ones float along the surface and move around the ocean. Helen explained a bit more about the look and ability of a moored buoy.

Helen Beggs:

It's a very large buoy with a very long chain at the bottom of it to tether it to the bottom of the ocean. So, it may be several kilometres long if it's in the deep ocean, it's probably a sort of roundish, a couple of metres, perhaps I'm not sure of the exact size, but they are quite large. And on these buoys, they have instruments that are weather sort of instruments. It's basically a weather station on a buoy. But underneath the water they have temperature. They might have current senses, pressure sensors, of course, and they measure the salinity as well. So, and some of the measure, other things like the chlorophyll fluorescence or something, but they have all sorts of instruments on them.

So, they are quite large and extremely expensive. And the Bureau of Meteorology has actually deployed for many years in the Southern Ocean, South West of Tasmania the same sort of buoys. So, it's called a flux buoy, it measures air sea flux, accurate weather data as well as ocean data. I happen to know they are extremely expensive and to have an array of them costs millions of dollars a year. Unfortunately, because of the expense in recent years, the number of them has decreased because of the cost.

Some of the very first moorings started in 1980 and they were probably the most important ocean observations long-term that we have, well apart from ships going back so far. But they started in 1980, so they don't go back as far, but they were calibrated sensors on moorings that measured all types of variables. It wasn't just the temperature.

So, the TAO array started in 1987 and that is best way we have to monitor consistently and accurately what ocean temperatures have been doing. And they are particularly important for the validation of the satellite SST data too because they are stable. They are calibrated and accurate, and they stay in one place because their moored, whereas the drifting buoys are really helpful, but of course, by definition, they drift. And once they are calibrated, you cannot go back and calibrate them again and check them. Whereas the mooring, ships go to them every year to maintain them and to swap over the sensors and to calibrate them. So, they are particularly important and there are other mooring arrays now that started later in the Atlantic and Indian oceans, but they started with the Pacific specifically because they realised that El Nino was so important.

Since the late 1990s they started to deploy ARGO profiling floats, which are a little bit like, a pink torpedo or something. They go up and down through the water. And they are also extremely important for ocean models and as input into seasonal prediction models. And they have accurate sensors on board to measure the temperature and the salinity and pressure.

And they are probably the most important input now into ocean models. Because they spend most of their time underneath the water. They're not affected by the currents as much, unlike the drifting buoys that drift with the currents. So, once you deploy them in one region of the ocean, they pretty well stay in that region without drifting away too much. So, we now have a very good array. That's totally global of, ARGO floats their called.

There are many different types of platforms which have emerged over recent years. So, we are now in a much better space than we were in the 1980s, say where we had only very few drifting buoys, mainly ships, a few drifting buoys and no mooring, very few moorings. Whereas now we have much, much more data.

And over the years they have improved, in that they have more sensors on each float, they can measure biogeochemical data as well now, some of them, not all, so they have a range of applications, they are the darling of ocean modellers, they just love them. They are so important to them.

But they're not the only source of temperature and salinity data at depth. There are other instruments that are put on seals, sea lions and turtles. So, we actually get a free ride as it were from seals. And the data comes into the Bureau and it's placed on the GTS so that it's available to models around the world too.

Jemma Pearl:

The biggest game changer for collecting sea surface temperature data has definitely been the use of satellite technology, but that doesn’t mean the in-situ equipment, like the buoys, are not also very important.

Helen Beggs:

So, it started off in 1964, which sounds like a long time ago. It was before we landed on the moon. It was back in the very early days when people started to put satellites up in space. One of the very first satellites, which was the Nimbus 1 satellite launched by NASA in 1964. That had something called an HRIR sensor onboard an infrared radiometer, which could measure, I think, one frequency. So only one wavelength, but it could measure the brightness temperature of the ocean. And they were flabbergasted. They were absolutely amazed when they saw the first pictures of the ocean and they went, wow, it's all swirly bits.

This is amazing. We didn't know it had swirly bits in the ocean. We didn't know that there were eddies. It was the first time that they'd seen an Eddy and they didn't realise that that's what was in the ocean. Which seems amazing to me that they didn't realise from their ship observations that, the ocean actually behave like that. But so that was the first image from space of ocean temperature. And, of course it became a lot more accurate after that, because they had to add more wavelengths so they could measure it more accurately. And it wasn't till 1981 when they put the advanced very high-resolution radiometer, ABHRR on to NOAAS polar orbiting environmental satellites. Which started in 1981, with NOAA 6 satellite that they could measure pretty accurately SST from space.

And in fact, scientists still use the data starting in 1981, which is why I measure it because so much of our climate data record of SST starts with that satellite. So, it was incredibly important. And of course, it's been going ever since. So, the calibration back in the 1980s left a bit to be desired. Technology has come a long way since then, but what is also cool is that just in the last few years, my colleagues in the UK have been able to go back to the raw data from those early NOAA satellites and recalibrate it right from raw counts to SST. And they now have more accurate data from 1980s.

But the big, big challenge also is that back in the eighties, we had so few in situ SST observations. So, we only had very few drifting buoys, very few moorings and the ships, but the ships had engine intake, sensors. They weren’t so accurate, so it’s much more difficult to ground truth that data.

These days it is so much easier, because we have a whole lot more accurate in situ SST data and also the sensors on the satellites are much better calibrated. And I got involved in satellite SST data when I started in the bureau in 2003 and ever since I have been trying to improve the satellite SST products that Australia produces basically. So, these days, we have come a long way since 1981.

Jemma Pearl:

What new technology is coming forward to continue the collection of temperature data?

Helen Beggs:

IMOS is funding testing of new technologies because we've realised that yes, we do need to move with the times. So, there are new types of drifting buoys like wave buoys that are being tested. It's very important to measure waves with buoys on the ocean, of course. And also something that's come along in just the last few years is something called Saildrone, which as the name implies, it is a little sailing boat that is controlled remotely by pilots a shore. And they program it just as they would a program, a glider is pre-programmed to go along and set path, but it's also monitored and it can be, it's route can be changed if needed then a Saildrone can also be guided.

And they have a number of instruments on board. So, it sails with the wind. It can measure ocean temperatures, as well as meteorological data and, and other types of ocean data.

Jemma Pearl:

We thank Helen for her time and greatly appreciate her willingness to share the vast knowledge she has about the collection and use of sea surface temperature data.

Next time you see a sea surface temperature map in the Fast Break or Very Fast Break, think about all of those buoys collecting data.

Ethan Berry:

We hope that this episode has helped to shine a light on how important sea surface temperature data collection is and how it was quite difficult to collect it in the early days.

You can find more helpful links in the show notes and we’ll also leave an example of a sea surface temperature map if you’re interested, and you can get in contact with us at the.break@agriculture.vic.gov.au.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscribe wherever you get your podcasts. We would love to hear your feedback, so please leave a comment or rating and share this series with your friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Episode 1: History of seasonal climate and climate driver information with The Break team

Ethan Berry:

Hi, I am Ethan Berry.

Jemma Pearl:

And I am Jemma Pearl.

Ethan Berry:

Here at My Rain Gauge is Busted we talk about all things climate and farming, and explore stories from farmers, researchers and innovative folks, about our weather, the seasons and the climate, about what’s normal and what isn’t, and the great work underway that is well setting us up for the future. Today in what will be the first episode of My Rain Gauge is Busted, we thought we would start by talking about some of the history and the projects in Victorian agriculture that have brought us to where we are today regarding decision making on-farm with seasonal variation and climate in mind, but the main question we want to answer today is what makes The Break team qualified to talk about this stuff?

Jemma Pearl:

We will be introducing you to a few experts that will become familiar voices to you on this podcast. I have been working with The Break team for a while now, and as the overall understanding of the way that climate affects our conditions gets stronger, we work harder to make sure that climate science can be useful for making decisions on farm.

As you listen to each episode of this podcast we will be tracking down key information from our local leaders in the industry.

Ethan Berry:

Now that you've met Jemma and I, let's take you back to July 2005, where it began.

Chris Sounness:

I think it was emerging, so I think there was an understanding about El Niño and La Niña. There was some other climate drivers that were starting to be understood through the science community, what might've been driving, the variations in the climate and the weather. I think that was sort of just starting to come to the fore, and through the nineties there'd been, I think, a fairly big investment in seasonal climate understanding, and it was getting to the point where there was some stories to be told.

Jemma Pearl:

That was Chris Sounness, who led the initial Break project here at Agriculture Victoria in partnership with De-anne Ferrier.

De-anne Ferrier:

Climate and weather was talked about indirectly at a lot of our Top Crop farmer meetings. We often presented rainfall deciles and what that meant for crop growth, so integrating rainfall that everyone talks about and what our crops looked like at the time. We also used French and Schultz, and PYCAL yield projection calculations, and we discussed those regularly at our meetings, which was really great, because as the season evolved you could continue to have that discussion.

De-anne Ferrier:

I don't think it was until we received funding from the Managing Climate Variability project that we actually discussed climate drivers in depth, but prior to that it was an indirect conversation, but growers always talk about rainfall and concepts around that, and crop growth, so indirectly we've talked about it for a long time.

Jemma Pearl:

The most classic example of a climate driver is the El Niño-Southern Oscillation, which you might've heard of before. There's a lot of climate drivers around the world and they have a big impact on rainfall. We asked Dale Grey, who's been working on The Break products since their inception, what the understanding around climate drivers was at the time.

Dale Grey:

So Back then, it was, initially when we started, was very much about ENSO, El Niño-Southern Oscillation, El Niño and La Niña, because that was perceived to... There was a feeling around that that didn't affect Victoria, or hadn't affected Victoria much. It was a Queensland thing, and I must admit, I was probably of that belief as well, because I'd seen data and analysis to suggest that that was the case. But once you started looking into some of this stuff, it certainly became apparent that that wasn't the case, that certainly El Niños and La Niñas had absolutely affected Victoria and quite significantly so, but even up in Queensland, there are years where El Niño and La Niña hasn't affected Victoria, and it was sort of important to try and sort of tease out the differences in some of those years, I suppose.

Dale Grey:

The interesting thing was that in 2006, that the phenomenon called the Indian Ocean Dipole, while it was originally done in a paper in 1993 by Japanese researchers, had really not been talked about at all in anything that I'd heard of. I learnt of the Indian Ocean Dipole in 2006, and that was a bit of a revelation because it started explaining some other years, which had been kind of dry where El Niño hadn't necessarily been to blame.

Dale Grey:

What was also a revolution at that time was that Peter McIntosh and Gary Meyers from CSIRO atmospheric physics in Hobart had put together a paper where they had actually classified the last sort of 115 or 120 years using historic sea surface temperature data sets, but we had years with the climate drivers against them. That was a revolution, because that allowed you to plug it into a spreadsheet. If people don't know, I'm a bit of a data nerd, so it was possible to start looking at the effects of both of these climate drivers on rainfall. It turned out that the Indian Ocean Dipole had a very similar effect to ENSO in Victoria, and some of our driest years had been when it had coupled up together with... At the drier end of the Indian and Pacific Ocean, and some of our wettest years were when it had coupled together in the wet end of Indian and Pacific Ocean phenomena.

Jemma Pearl:

Dale Grey is a seasonal risk agronomist here at Agriculture Victoria. Seasonal climate research, and extension, is still a very young science. We also, now understand that it is not just the El Niño-Southern Oscillation and the Indian Ocean Dipole that affect our climate here in South eastern Australia, but also the subtropical ridge, the Southern Annular Mode, the Madden–Julian Oscillation, and East Coast lows, just to name a few.

Jemma Pearl:

They all have different effects on how much rain we get, and some years we see them, and some years we don't. I asked Dale about these more recent climate driver discoveries.

Dale Grey:

Well, they came along a bit later as we discovered them ourselves, I suppose. It was a time where the members of the project were going along to all manner of conferences around Australia, on climate and weather. I'm sure that Chris, and De-anne, and myself, we can well remember some of those early conferences where we've listened to the first three or four talks, and we've looked to each other and just gone, "Didn't understand a thing they said there. I didn't understand a single one of those images and plots."

Dale Grey:

We were starting at the bottom end. Well, we had no knowledge whatsoever, almost, so everything we were hearing and listening was new. Everything was scary, and so it took a long time to kind of develop our understanding and confidence, but things like the subtropical ridge of high pressure, which was done by Bertram and Timbal from the Bureau, and the Southern Annular Mode, which was invented by Gary Marshall from the UK. That kind of appeared in some of these conferences that we were going to, and instantly we were able to look at these things and go, "Oh, I think we can use that, or we can incorporate it into our material, because it's clearly a climate driver that affects us... in Victoria."

Dale Grey:

Once again, the other good thing was that for both of those climate drivers it was possible to get data sets where you could characterise years where things had been positive, or negative, or high or low pressure. Once again, you could start doing analysis of rainfall, and convince yourself, and hopefully the farmers that we're talking to, that indeed these climate drivers had at times significantly affected Victoria's rainfall.

Jemma Pearl:

The Break newsletter took off with more than 1300 subscribers.

De-anne Ferrier:

The beauty of it was that we enjoyed being the conduit between the science research community and the agricultural on-ground farming community. It was a one-stop shop for information for both sectors, which that was our aim, I suppose. I think without that link we wouldn't have generated the interest for people to engage, and we wanted to make this one worthwhile and special. We had an overview of what was currently happening across the regions. That morphed into also including the water storage's, because at the time water storage was a major discussion. Still is. The next page was about climate drivers. Then we also had decile and PYCAL yield projections on a page. So, looking at what the rainfall was, how that fitted with long-term averages, and what our potential yields were, and then we also added yield profit. So, Linking the crop science into the climate science, and just general rainfall for yield projections and ultimately income.

De-anne Ferrier:

And, towards the end, we had what we called Chris's baby, The Fiver. Once we got there, it was a really thoughtful, interesting, left field discussion, often humorous, a little tongue in cheek, but we thought it had personality, and it was a really useful engagement. With the number of emails, because the newsletter became so popular, at times we had 2000 emails being sent out, and so we would crash the system at DPI Horsham. Anyway, we had a lot of power, so we wouldn't send it until later at night when people had knocked off. Anyway, connectivity still remains an issue to this day, so I'm not sure how that would be overcome now.

Jemma Pearl:

As the team better understood the seasonal climate space and the models, it became very evident to them that when a range of the different climate models across the world were all predicting and indicating the same patterns that was when seasonal model prediction could be most powerful.

Dale Grey:

Chris Sounness was at a meeting somewhere in Canberra or Melbourne and was just proposing the theory that could the Bureau or could someone start summarizing what a lot of the models were saying around the world. Rather than just looking at one model, could someone put up analysis of a number of models. The Bureau come back, sort of saying, well, they wouldn’t feel quite uncomfortable making comment on other researchers models from around the world, so clearly it fell to someone who was independent of that kind of model process, and Chris rang me up one day and said, "Do you think you can have a crack at looking at a number of different models and summarising them?" I thought, "Gee whiz, that's going to be interesting."

Dale Grey:

It was really a case of searching around and seeing a) what I could find, what was publicly available, and what was updating itself, sort of on a monthly basis, and had an archive of things that you could go back and look at it. There might've been only about eight or nine models initially in that very first newsletter, and it's essentially the same thing that we see today. It's that analysis of the Niño 3.4 area in the middle of the Pacific, the analysis of the Eastern Indian Ocean and whether it's cold or warm, and whether there's potential Indian Ocean Dipole activity happening there, and analysis of what the rainfall looked for Victoria as a whole, and temperature.

Dale Grey:

At that time we were running Breaks and Fast Breaks. They were coming out within about a week of each other. It was a crazy time.

Chris Sounness:

Dale really ran with it and it sort of worked out in a way, when one page expressing the 10 or 15 different models in a one page snapshot, crammed full of information, but for a certain group of people that are information hungry, it was very popular product, because as I say, put all the models into one spot allowed you to see how they're all going. If it was consensus or not, because that was a lot of our messaging, is when there was consensus, that was when you would be most alert to what the models were saying, and when they're not saying much, or they're all going in different directions, you probably don't get that excited by them.

Jemma Pearl:

The Fast Break table quickly became a very powerful tool to summarise what is happening in seasonal forecasting. This was the first time in South Eastern Australia, that information about multiple different model outputs were summarised in a format accessible to the agricultural community.

Dale Grey:

Yeah. For the first time we were probably putting these model outputs in a table that were allowing farmers to kind of look at them, I suppose, we had a hypothesis that looking at a number of models would be better than looking at one model alone. Particularly when we now had some real big computer models working as well as some statistical systems as well, which were much relatively simpler. I think it would have been, I'm trying to remember, I think that very first year that we did it, turned out to be a positive Indian Ocean Dipole, and there was a lot of sniffs of drier around at that time as well. Yeah. There was something going on in that very first one, that was a very different story than just looking at the statistical forecast from the Bureau, there was more exciting things going on, and it was going to be a pity not to share them with people.

Jemma Pearl:

While the team were onto some winning products with The Break and Fast Break newsletters, it didn't stop them looking to other communication methods to help upskill the entire agricultural industry.

Graeme Anderson:

I guess we were at a conference in Sydney listening to some climate scientists talk about the big 2006 drought and someone referred to it as the three headed dog, because the El Niño in the Pacific and the IOD in the dry phase in the Indian ocean, and then SAM was... The fronts were a long way south, and we had a bit of a chat about it, thinking three headed dog, that's a good analogy, but we've never seen a three headed dog. When we go visiting farms, we're used to the sheep dogs coming up and surrounding you, and I grew up in a farm, so we were conscious of there's dogs running around, but also made a bit of sense that it's not just one dog, it's probably each of them.

Graeme Anderson:

The dogs sort of work as a bit of a pack, but also individual dogs have different behaviours, so it sort of made sense that some of those big droughts when all of the dogs went through the fence and misbehaved, and that they had moods each year, like those oceans did. Whenever we were doing a lot of face-to-face presentations with farmers, or whenever we said, "It's these four sheepdogs that round up our rainfall, and sometimes they're really behaving and all's going well, but then sometimes they can really misbehave and it makes the job of farming a lot harder." It always got a bit of a smile, and a bit of a laugh from farmers, so we knew we were sort of onto a bit of a good little yarn.

Jemma Pearl:

That was Graeme Anderson, the climate specialist here at Agriculture Victoria, explaining how the award winning Climatedog video series came to life. You can find links to check out each of the Climatedog videos in the show notes.

Graeme Anderson:

Yes, it won the SCINEMA award, Science Short Animation of the Year award, and a few things like that, and they've been gone... DPI New South Wales, adapted them for their region, and then they've been adapted through the Managing Climate Variability Program. They've been adapted for all of Australia now, these Climatedogs, that are sitting on the Climate Kelpie website, so they've gone on, and I guess there was a good lesson in that just about while the science can be quite complex, it can always be simplified into something that's entertainment, that gets the message across.

Graeme Anderson:

I've been with the department for 30 years and I'm working in extension science, extension and communication, I’ve always spent a lot of time around farms and agriculture.

Graeme Anderson:

I got into the climate stuff, which was in the early 2000s, when I read a climate science report for Australia, and couldn't quite believe what I was reading about what was being measured, what was happening in the atmosphere and oceans. I thought, "You know what? We rely on climate a lot in agriculture. We probably should be tapping into this a bit more," so that was quite a big change there, because thinking, we have a lot to do with ag science, but probably in agriculture, we're not as well connected to the climate and atmospheric science that's going on, as we should be, because it's all important. We know how much variation of seasons, and seasonal variability, and climate risk has a really big impact on farm businesses.

Graeme Anderson:

I guess, it was from that point that we decided to try and spend a bit more time hanging around with the climate scientists and try and do some extension and help explain that to Victorian farmers.

Jemma Pearl:

Dale, Chris, De-anne, and Graeme were all quick to point out that without the knowledge and assistance by many others, the awesome products that form The Break portfolio would not be what they are today.

De-anne Ferrier:

One thing that was great with the communication with the science researchers, was that we could have a discussion two ways. They were interested in what was going on at the ground and in the paddock, as much as what we were interested in, in regard to their scientific information or papers that were being disseminated. It was a two-way conversation where people were both engaged, and that was a really strong relationship to work on.

De-anne Ferrier:

It was really quite heartwarming to see The Break newsletter sitting on the desks of people at the BOM when I'd visit. I thought, "Oh, that's nice. Woo-hoo."

Dale Grey:

Over that time, the CSIROs, and the Bureau of Meterologies, were incredibly generous to us. If we had questions, we'd ring people up and ask them. They'd show us where websites were secretly hidden, allow us to get into them and things, and we were often going down to the Bureau of Meteorology and allowed to sit in on some of their discussions and their meetings that they were doing in their own forecast formulations and stuff. It was an incredible time of learning back then. It really was.

Chris Sounness:

The Break wasn't a product of its own, it was a product of a whole range of people who are far more skilful, far more knowledgeable than De-anne, Dale, and myself. We had the opportunity to interact with them and learn from them, and synthesise what they were saying, and then they would provide constructive feedback on what we'd do well, and the stuff ups we were making  along the way, and how to hone that. So, I think that's probably the most important part about the Break was we were in a supportive environment with the best leading thinkers in Australia, from both an agronomic community, the farming community, the science community, and they were all there cheering us on.

Chris Sounness:

Myself, I was always keen to try and make it not just technical and dry, and I wanted to make it so it expressed a bit of personality, and wasn't just about the technical, but a bit about the story. It was important to, I suppose, express it from our point of view, and the story was just as important as the facts. I think some of those Break surveys and the climate surveys we did over the period of time were absolutely invaluable in helping us, I suppose, improve the understanding of the audience and improve what worked and what didn't work, who read it and who didn't read it, and what they read and what they didn't read. Yeah, I think understanding the audience is so important.

Dale Grey:

It was something we could kind of hang our hat on, I suppose, that we had given skills to farmers to look at things that had been around, oceanographers had been doing it for 20 or 30 years, maybe longer, but it had all been secreted away in the hallows of research and science. All of a sudden we could see something that looked like, "Oh, this was interesting and cool, and worth monitoring, and it was worth talking about."

Jemma Pearl:

Collaboration and improving their methods led to a few things getting cut, and new things being born to take their place. The goal was always to get the most useful info right in the hands of people that need it, so that farming and agronomic decisions could be made, and so YouTube was the next chapter in this story.

Dale Grey:

I'd been doing lots of talks and even webinars back then, and they'd often go from half to three quarters of an hour, and Graeme said, "Can we cut to the chase? Can we cut this information down to three minutes?" I was completely unconvinced that that was possible, but anyway, we had a go, and that first YouTube clip was pretty lame, because we didn't even have a script, but we pretty quickly learnt that if you've only got three minutes to talk about something, every second is precious.

Jemma Pearl:

So, over 15 years, things have evolved and changed. We no longer produce The Break newsletter, the thing that started this all off. The Fast Break newsletter continues to be produced monthly during the growing season, which has also grown to cover summaries for South Australia, Tasmania, and Southern New South Wales, as part of a Grains Research & Development Corporation project.

Jemma Pearl:

The Very Fast Break with Dale comes out each month, breaking down the month's rainfall, soil moisture and ocean activity, and now covers South Australia and southern New South Wales as well as Victoria. The Climatedogs have gone on to become their own phenomenon with awards and national recognition. There's a climate webinar series, and now this podcast, but the aim still remains to bring relevant information to the agricultural audience.

Ethan Berry:

So, that brings us to now, and here at The Break, we believe that anything that's out there helping get good information in the hands of people that can make the most of it is exactly what’s needed. There's a lot of different approaches and technologies that are available today, and a lot of busy people making strides and trying new things, but it's never been more important to understand more about what's happening with our climate. What's driving wetter and drier years, and what are some of the significant changes happening because of climate change that impact our farms locally?

Ethan Berry:

There's a real thirst for people that want to dig a bit deeper, and that's the opportunity that we want to provide here at The Break team. We want to talk about some of the questions we receive regularly, some of the key things that you need to know, and we'll bring you the experts to answer some of the trickier issues around climate and farming. Dear listeners, this is My Rain Gauge is Busted.

Speaker 1:

Thank you for listening to My Rain Gauge is Busted. For more episodes in this series, find us and subscriber wherever you get your podcasts. We would love to hear your feedback, so please leave a comment or rating and share this series with you friends and family.

All information is accurate at the time of release. Contact Agriculture Victoria or your consultant before making any changes on farm.

This podcast was developed by Agriculture Victoria.

Page last updated: 06 Jun 2022