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Key things to know about ENSO
- ENSO describes the position of warm and cool water, the strength of winds and atmospheric pressures in the Equatorial Pacific Ocean region.
- When oceans heat up, moisture evaporates into the atmosphere. Under the right conditions ENSO can deliver a lot of moisture to Australia which becomes available to fall as rain.
- ENSO is important for Victoria, especially during spring.
- Other weather processes, like cold fronts, help to trigger rainfall events.
- Three phases: El Niño, La Niña and Neutral help to describe the different states of ENSO.
La Niña (SOI positive)
Historically, La Niña years deliver more moisture to Australia, because warm waters gather closer to our east coast. Combined with increasing trade winds this provides more moisture in the atmosphere and directs it towards eastern Australia.
In the past La Niña years have been correlated with an increased chance of wetter springs.
El Niño (SOI negative)
During the El Niño phase warm waters head towards South America and trade winds are weakened. This results in less atmospheric moisture available for rain in Australia. In the past, El Niño years have been correlated with an increased chance of drier springs.
Where to go for more information
For more information about ENSO visit some of the pages below.