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El Niño–Southern Oscillation and Indian Ocean Dipole remain neutral

Indian Ocean Dipole

MELBOURNE, Australia – The tropical Pacific remains neutral with respect to the El Niño–Southern Oscillation (ENSO). Atmospheric and oceanic indicators of ENSO including the Southern Oscillation Index (SOI), trade winds, cloudiness near the Date Line, and sea surface and sub-surface temperatures in the tropical Pacific Ocean all continue to persist at levels consistent with neutral ENSO, reports the Bureau of Meteorology of the Australian Governement.

Six of the eight climate models surveyed by the Bureau indicate that ENSO is likely to stay neutral through the southern hemisphere winter, meaning it may have limited influence on Australian and global climate in the coming months. The remaining two models suggest La Niña may develop during winter. However, ENSO predictions made during autumn tend to have lower accuracy than predictions made at other times of the year. This means that current ENSO forecasts beyond May should be used with some caution.

The Indian Ocean Dipole (IOD) is neutral. The IOD typically has little influence on Australian climate from December to April. Of the six international climate models surveyed, most indicate neutral IOD for the coming months. One model briefly reaches positive levels at the end of autumn, while several tend towards negative levels during the southern hemisphere winter. However, similar to ENSO, accuracy of IOD forecasts beyond autumn is low.

Recently the Southern Annular Mode (SAM) has been positive but is forecast to return to neutral levels over the next few days and then remain neutral for the following three weeks. SAM has little influence upon Australian rainfall in autumn.

The Madden–Julian Oscillation (MJO) is forecast to move into the Australian region, but its influence on rainfall over northern Australia is likely to be short-lived or insignificant, as it weakens rapidly in early April.