Intraseasonal Air–Sea Interactions at the Onset of El Niño

Abstract

Abstract The role of the Madden–Julian Oscillation (MJO) for the onset of El Nino is examined. A preliminary analysis compares tropical Pacific variability during three boreal winters that initially had similar distributions of sea surface temperature (SST). During the winter of 1996–97, strong MJO activity led to west Pacific cooling and central Pacific warming. Subsequently, convective activity migrated from the west Pacific into the central Pacific and the accompanying westerly surface wind anomalies promoted further central Pacific warming. Strong MJO activity was also evident during winter 1989–90 and the early stages of El Nino development were evident that winter with similar evolution to that during 1996–97. However, the development of El Nino was aborted in May 1990. It is speculated that a full El Nino did not develop during 1990 because the subsurface ocean structure would not support that development. The MJO was relatively quiescent during the winter of 1981–82. A strong El Nino developed dur...