Negative Indian Ocean Dipole event continues, says Bom in its new Climate Driver Update

MELBOURNE, Australia – The negative Indian Ocean Dipole (IOD) event continues reports the Bureau of Meteorology of the Australian Government in its latest update. A negative Indian Ocean Dipole increases the chances of above average winter–spring rainfall for much of southern and eastern Australia. It also increases the chances of cooler than average days in southern Australia for winter–spring, and warmer than average nights across northern Australia.

The most recent weekly IOD index value is −0.76 °C, with warmer than average waters in the eastern tropical Indian Ocean, and average to cooler than average waters in the western tropical Indian Ocean. Most climate models surveyed by the Bureau predict negative IOD conditions are likely to persist throughout spring.

The El Niño–Southern Oscillation (ENSO) remains neutral with most oceanic and atmospheric indicators within the neutral range. While pressure patterns show some La Niña-like characteristics, as indicated by the latest Southern Oscillation Index (SOI) 30-day value of +15.1, it is likely that some of this shift in pressure is driven from warm conditions in the eastern Indian Ocean. Most climate model outlooks indicate the central tropical Pacific is likely to cool over the coming months, with three of seven models surveyed by the Bureau indicating this cooling will be enough to reach La Niña thresholds in spring, with the remaining four models staying neutral. Along with the negative IOD, this may be contributing to the wetter than median climate outlooks in Australia

The Southern Annular Mode (SAM) index has recently been positive, but is forecast to return to neutral levels in the coming days, and remain so for at least the next fortnight. A neutral SAM has little influence on Australian climate.

The Madden–Julian Oscillation (MJO) is currently in the Western Hemisphere. Most climate models indicate the MJO will move towards Africa over the coming week, although climate models indicate the strength of the MJO could range from moderate to weak. An MJO near Africa typically means below average cloudiness and rainfall across much of much of India and parts of southeast Asia.

Climate change continues to influence Australian and global climate. Australia’s climate has warmed by 1.44 ± 0.24 °C over 1910–2019, while southern Australia has seen a reduction of 10–20% in cool season (April–October) rainfall in recent decades.