Monday 29 May 2023

Positive Indian Ocean Dipole continues to weaken, Enso remains neutral

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MELBOURNE, Australia – The positive Indian Ocean Dipole (IOD) continues to weaken, while the El Niño–Southern Oscillation (ENSO) remains neutral, reports the Australian Government Bureau of Meteorology. The IOD value has fallen from a peak of +2.2 °C in mid-October, to the latest weekly value of +0.6 °C.

Warmer than average waters persist near the Horn of Africa, but waters in the eastern Indian Ocean are now near-average.

While the index is still above the positive Indian Ocean Dipole threshold of +0.4 °C, most international climate models surveyed by the Bureau indicate the positive IOD will dissipate in January. The rate of current weakening would suggest a return to neutral is likely by early January.

Positive IOD events in spring (as happened this year) are often associated with a more severe fire season for southeast Australia in the summer months.

In the tropical Pacific Ocean, while most indicators of the El Niño–Southern Oscillation are neutral, warmer than average sea surface temperatures in the far western tropical Pacific may be contributing to some changes in local weather patterns over the region. International climate models forecast ENSO-neutral until at least autumn 2020. When ENSO is neutral, it has limited influence on Australian and global climate.

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