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ENSO & SST

ENSO and Sea Surface Temperatures

The tropical Pacific Ocean continues in a weak El Niño state, but the atmosphere is still only partially coupled to the tropical ocean. The NINO3.4 average anomaly was +1.0°C in November (same as in October), and +1.0°C for September to November (up from +0.8 in August-October). Subsurface temperature anomalies were positive in the top 100 m across most of the Equatorial Pacific. Positive zonal wind anomalies were evident in November, but mostly west of the Date Line. Outgoing longwave radiation (OLR) and rainfall anomalies suggest the SPCZ is lying northeast of its normal location (west of the Date Line), and precipitation is suppressed over Indonesia, consistent with El Niño events. The Southern Oscillation Index (SOI) was –1.1 for November (three-month September-November mean –0.7), indicative of a weak mean signal in the tropical circulation.

Most available models indicate weak El Niño conditions over the December to February of 2004-05, with only a few indicating El Niño conditions persisting into March to May 2005. Almost all models indicate neutral conditions by June to August 2005. No model is predicting substantial cooling in the equatorial Pacific over the next 9 months.

Sea surface temperature anomalies (°C) for November 2004

Hornwort can form very dense, tall weed beds in the littoral zone of lakes. [NIWA]

Mean sea surface temperatures (°C) for November 2004