Indian Ocean influences on Australian climate
Sea surface temperatures
Indian Ocean sea surface temperatures impact rainfall and temperature patterns over Australia. Warmer than average sea surface temperatures can provide more moisture for frontal systems and lows crossing Australia.
Indian Ocean Dipole
Sustained changes in the difference between sea surface temperatures of the tropical western and eastern Indian Ocean are known as the Indian Ocean Dipole or IOD. The IOD is one of the key drivers of Australia's climate and can have a significant impact on agriculture. This is because events generally coincide with the winter crop growing season. The IOD has three phases: neutral, positive and negative. Events usually start around May or June, peak between August and October and then rapidly decay when the monsoon arrives in the southern hemisphere around the end of spring.
Indian Ocean Dipole years
- See also: Links open in new window
- Indian Ocean Dipole outlook
- Indian Ocean outlook model summary
- Graph of latest IOD Index
When the Indian and Pacific oceans work together
The El Niño–Southern Oscillation (ENSO) is the major climate driver in the Pacific Ocean and can have a strong impact on Australia's climate. El Niño years are typically warmer and drier over eastern Australia and La Niña years tend to be cooler and wetter over much of the country.
When El Niño coincides with a positive IOD, the two phenomena can reinforce their dry impacts. Likewise, when La Niña coincides with a negative IOD, the chance of above-average winter–spring rainfall typically increases.