The tropical circulation in the Australian and Asian region - November 2009 to April 2010

Abstract

A summary of the broadscale tropical circulation from 70°E to 180° for the six months from November 2009 to April 2010 is presented. A weak to moderate El Niño state of the El Niño Southern Oscillation (ENSO) persisted during the season. The sea surface temperature (SST) remained warmer than normal in the central and eastern equatorial Pacific during the season. The warmest waters in the equatorial Pacific remained close to their climatological location in the northwestern Pacific. The Southern Oscillation Index (SOI) remained mostly negative throughout the season. The onset of the Australian monsoon over northern Australia occurred around 5 January 2010, later than the climatological onset date, with retreat north of the Australian continent in mid-February. However, monsoonal rains affected northern Australia during April, and Darwin’s rainfall for the season was above average. The Madden-Julian Oscillation (MJO) signal was not clear as the convection during the season remained mostly confined to the western half of the tropical Regional Specialised Meteorological Centre (RSMC) area. A total of eighteen tropical cyclones, fewer than average, developed in the RSMC area during the period.