Maturing El Niño event in the Pacific Ocean
The Bureau of Meteorology report a mature El Niño conditions continue to dominate the equatorial Pacific Ocean. Ocean surface temperatures in the central Pacific remain at levels not seen since the El Niño events of 2002-03 and 1997-98, with values more than 2°C above normal in places along the equator. Leading climate models continue to suggest tropical ocean temperatures will remain above El Niño thresholds into the new year, though most indicate the El Niño will decline after the southern hemisphere summer.
Over the past fortnight, the Southern Oscillation Index has remained steady at levels typical of an El Niño event, while temperatures below the tropical Pacific Ocean surface have cooled slightly in central regions. However, Trade winds have weakened considerably over the same period, which may lead to some renewed warming of the equatorial Pacific Ocean.
The poor start to the northern wet season and the occurance of spring heatwaves are both typical impacts for an El Niño event. However, the influence of El Niño events on Australian rainfall typically declines by mid to late summer.
The Indian Ocean Dipole (IOD) has a reduced impact upon Australia over the summer months. The Bureau’s POAMA model suggests neutral IOD conditions may be present through autumn 2010.