Seasonal climate summary southern hemisphere (spring 2010): La Niña strengthens

Abstract

Southern hemisphere circulation patterns and associated anomalies for the austral spring 2010 are reviewed, with emphasis given to the Pacific Basin climate indicators and Australian rainfall and temperature patterns. Spring 2010 saw a continued strengthening of the La Niña conditions which started to become apparent in the autumn. All ENSO indices were showing a strong La Niña signal throughout the spring, with the October value of the Southern Oscillation Index (SOI) equalling its highest value on record. The Southern Annular Mode (SAM) also remained strongly positive during spring 2010, with the SAM index setting a monthly record in November. Additionally, the observation based SAM index set a seasonal record in spring 2010. In the Australian region, spring 2010 was the wettest spring on record with above average rainfall across most of the country. In sharp contrast however, southwestern Australia reported its driest spring on record following on from the driest winter on record. Temperatures were generally cooler than average across central and southern Australia, with the widespread rainfall contributing to the cooler temperatures. Warmer temperatures were experienced in some northern and coastal regions