ENSO & SST

ENSO and Sea Surface Temperatures

Positive SOI during May

Slightly above average SST west of the Date Line

The monthly SOI rose markedly in May to +1.3 with the three month mean (March – May) close to neutral (-0.2). The oceanic and atmospheric conditions indicated a neutral phase of El Niño Southern Oscillation (ENSO) during May 2004. May SSTs were warmer than average in the western and central equatorial Pacific (NINO3 and 4 regions) and cooler than average in the eastern equatorial Pacific (NINO1 and 2 regions). Subsurface temperatures show a positive anomaly in the top 100 m in the central Equatorial Pacific, which has propagated eastwards and upwards since April. May averaged OLR anomalies show a region of suppressed convection just west of the Date Line, with weakly enhanced convection in Australian longitudes, a partial reversal of the April picture. Most global models indicate neutral conditions into spring 2004.

Sea surface temperature anomalies (°C) for May 2004

Mean sea surface temperatures (°C) for May 2004