Seasonal climate summary southern hemisphere (autumn 2009): signs of an El Niño in the Pacific

Abstract

Southern hemisphere circulation patterns and associated anomalies for the austral autumn 2009 are reviewed, with emphasis given to Pacific Basin climate indicators and Australian rainfall and temperature patterns. Autumn 2009 saw neutral or near-neutral conditions in the Pacific following from the La Niña conditions experienced since late 2008. By the end of May 2009, the equatorial Pacific showed consistent warming, and the Southern Oscillation Index (SOI) fell, reaching −5.1 in May. In the Indian Ocean, a positive Indian Ocean Dipole sea-surface temperature pattern started to establish itself during May. In the Australian region, autumn was drier than normal, with maximum temperatures above average over most of Australia.