Rainbow Radar

A new radar for the Wimmera and Southern Mallee

Agriculture Victoria, the Bureau of Meteorology (BOM), Wimmera Development Association (WDA) and other key community partners have been working together to establish a weather radar for the Wimmera Southern Mallee region.

The new radar is located on private farmland near Rainbow, 340 kilometres north west of Melbourne. It went live on 31 March 2020.

The C‐band 1‐degree dual polarisation Doppler radar delivers real-time weather information, including short-term rainfall forecasts, providing significant benefits to farmers.

The new radar has filled a gap in the country’s weather radar network and is enabling farmers in the Wimmera Southern Mallee to make better, more time-critical farming decisions.

The Rainbow Radar is now providing the region with real-time access to critical information about approaching weather.

Data available through the radar, and the accurate rainfall estimates and forecasts, helps growers to make informed choices about harvesting, tillage and the use of chemicals and fertilisers.

A March 2016 business case to address the service gap in the Wimmera Southern Mallee region of Victoria (prepared by the Wimmera Development Association with funding from the Victorian Government), identified agriculture as a key economic driver of the region and the largest industry sector in terms of employment, expenditure, gross revenue and regional exports.

It concluded that improved real-time weather services would show significant benefits to the region’s agribusinesses.

In response to the business case, the Victorian Government contributed $5 million from its Agriculture Infrastructure and Jobs Fund for the construction and commissioning of a Doppler weather radar, while the Federal Government committed $4.3 million for the radar’s maintenance and operating costs for up to 15 years.

Building the radar

Why Rainbow was selected as the radar site

The site for the new radar, near the town of Rainbow (one hour north of Horsham), was chosen after an extensive and detailed BoM process to identify a location that would best serve both the Wimmera region and the wider Australian weather radar network.

To ensure optimal performance from the radar, the site needed to be unencumbered by elevated topography relative to the site, as well as structures such as silos and buildings and vegetation such as large trees.

The site was also chosen to be easily accessible and to avoid airports and wind farms.

A skyline survey was undertaken to ensure the absence of any obstacles that may interfere with the radar’s operation.

Benefits of accurate weather forecasts

Weather is seen as the most important factor contributing to the success of the agricultural sector and farm businesses in the Wimmera Southern Mallee region.

Establishing a weather radar to provide coverage across the Wimmera Southern Mallee has numerous benefits including:

• improved farm business strategic decision-making especially around times of sowing, harvesting, chemical and fertiliser applications as well as the movement of stock
• enabling farm businesses to better manage weather-related risks
• providing short-term weather forecasting, enabling farm businesses to be more responsive to changing weather conditions
• community and social benefits through increased safety during extreme weather and emergency management incidents.

Expected economic benefits

The enhanced weather forecast information from the radar has the potential to improve decision-making by farmers that will enhance yields and reduce wasted costs.

Two critical activities — urea spreading and herbicide spraying — are expected to significantly benefit from the enhanced weather forecast information.

The WDA business case suggested annual benefits of $3.5 million.

These estimates of the potential benefits were conservative as they were:

• limited to only 2 key activities
• limited to urea spreading for wheat alone and not to barley or canola
• based on conservative estimates of reduced losses
• applied only to the Wimmera, as this is the area where greatest production benefits are available.

This provides confidence that the projected benefits are likely to be exceeded in practice.

Other benefits

Farm businesses can now make more informed decisions and reduce their business risks as a result of more precise weather data gathered from the Rainbow Radar.

The radar will give farmers advance warning of incoming rain, so they can decide when to apply fertilisers and herbicides.

Other benefits include:

• Safety — Radar data provides improved thunderstorm and heavy rain tracking.
• Flood warning — Radar data, blended with surface observations by the BOM ‘Rainfields’ System, give accurate and up-to-the-minute rainfall accumulations over a wide area around the radar.
• Emergency services management — Improvements in weather threat detection and weather warnings will flow through to improvements in business and community resilience and safety, while minimising the cost of unnecessary protective actions.
• Aviation safety and efficiency — Additional radar data will complement existing services to aviation.
• Forecast accuracy — Radar data can contribute to a general improvement in the skill of weather forecasts through the incorporation of data into models and the use of the data by operational forecasters.

What are weather radars and how do they work?

RADAR stands for Radio Detecting and Ranging. As indicated by its name, it is based on the use of radio waves.

Radar sends out electromagnetic waves similar to wireless computer networks and mobile phones.

The signals are sent out as short pulses which may be reflected by objects in their path, in part, reflecting back to the radar. When these pulses intercept precipitation, part of the energy is scattered back to the radar.

Radar-derived quantitative precipitation estimates offer a far greater spatial and temporal resolution in comparison with rain gauges — and greater accuracy than satellite-based rainfall estimates.

The radar at Rainbow is a Doppler radar.

Dual polarisation Doppler radars provide one of the best tools for observing real-time rainfall, storms and even debris in the atmosphere across large areas. As well as using electromagnetic waves to detect raindrops, hail and snow, Doppler radar can measure wind by detecting the speed of movement of the water they encounter.

How does a weather radar work?

Watch the Bureau’s weather radar video to find out more about how a weather radar works.

Image credits

Rainbow Radar, March 2020. Photo: CHS Group.