The tropical circulation in the Australian/Asian region - November 2007 to April 2008

摘要

A summary of the broadscale tropical circulation from 70 degrees E to 180, for the six months from November 2007. to April 2008, is presented. A mature La Nina state of ENSO (El Nino Southern Oscillation) prevailed early in the season, weakening towards the end of the season. The SST (sea-surface temperature) cool tongue pattern in the near equatorial far eastern Pacific near the South American coast extended west, past the date-line. The warmest waters in the equatorial Pacific remained close to their climatological location in the northwestern Pacific. The SOI (Southern Oscillation Index) remained positive throughout the season with a record high of +21 in February. Onset of the Australian monsoon over northern Australia occurred around 27 December 2007, close to the climatology. The signal of the MJO (Madden-Julian Oscillation) showed a regular periodicity of around 40-45 days during most of the season. A total of 23 tropical cyclones, close to the long-term average, developed in the RSMC area during the period.