ENSO & SST

ENSO and Sea Surface Temperatures

During January, El Niño/Southern Oscillation (ENSO) conditions in the tropical Pacific eased. The Southern Oscillation Index (SOI) rose to near zero in January, weakening the three-month November to January mean to -0.7. The NINO3.4 average anomaly was about +0.7 °C in January, slightly lower than in December. Subsurface temperature anomalies remained positive (between +1 and +2 °C) in the top 100 m across much of the Equatorial Pacific. Zonal wind anomalies were positive in the western Pacific in January, but the trade winds were near normal strength east of the Date Line. Out-going longwave radiation (OLR) and rainfall anomalies showed enhanced convection between 140 °E and 160 °E, and suppressed convection over Indonesia and east of the Date Line.

Most global climate models indicate neutral conditions (with positive NINO3.4 anomalies) until April 2005, and a few show warming during the May to July period. Almost all forecast neutral conditions by late winter. The latest US National Center for Environmental Prediction (NCEP/CPC) statement is for weak El Niño conditions continuing for the next three months.

The International Research Institute for Climate Prediction (IRICP) summary describes the present situation as a weak El Niño state, and gives an 85% chance of weak El Niño conditions continuing through until at least March 2005.

Sea surface temperature anomalies (°C) for January 2005

Mean sea surface temperatures (°C) for January 2005