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The negative Indian Ocean Dipole (IOD) is near its end

Updated: Dec 15, 2021

The Bureau of Meteorology, Australia has declared that La Niña will persist until the late southern hemisphere summer or early autumn 2022. La Niña events increase the chance of above average rainfall across much of northern and eastern Australia during summer.

Most El Niño–Southern Oscillation (ENSO) indicators show clear La Niña patterns. Sea surface temperatures in the tropical Pacific have cooled to La Niña thresholds, with climate model outlooks expecting them to cool further. In the atmosphere, cloud and wind patterns are typical of La Niña, indicating the atmosphere is responding to the changes in ocean temperatures. This feedback process is known as "coupling", and it means La Niña conditions are now expected to be locked in until at least the end of summer.

The negative Indian Ocean Dipole (IOD) is near its end, with IOD index values in the neutral range. However, some signs of the negative IOD persist with increased cloud over the eastern Indian Ocean and strengthened westerly winds. Climate models predict the IOD will remain neutral for the coming months, consistent with its typical seasonal cycle.

The sea surface temperatures over the east and central Pacific Ocean become cooler-than-average during La Nina. This affects the trade winds flowing over the ocean surface through change in wind stress.

The World Meteorological Organization has said in a press release that despite the cooling influence of the La Nina phenomenon, “temperatures in many parts of the world are expected to be above average because of the accumulated heat trapped in the atmosphere as a result of record high levels of greenhouse gases.”

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