ENSO & SST

ENSO and Sea Surface Temperatures

Despite the equatorial Pacific sea surface and subsurface temperatures being in an El Niño state, the atmosphere is yet to respond to the oceanic signals. The Southern Oscillation Index (SOI) weakened during September to -0.4, with the three month mean (July to September) at -0.7. Equatorial sea surface temperature (SST) anomalies rose compared to August. The NINO3 average anomaly was +0.9°C (August was +0.6°C) and July to September mean was +0.6°C. The subsurface temperature profiles show a region of positive anomalies (+2°C or more) in the eastern Pacific at ~100 m depth.

The positive zonal wind anomalies seen in August abated during September.

The majority of the available global climate models indicate neutral conditions to the end of 2004 and into early 2005 with above average SSTs in the NINO3.4 region. Less than half (5 out of 12) indicate El Niño conditions for the first quarter of 2005 and almost all models indicate neutral conditions by late autumn 2005. None of the models are predicting cool conditions in the equatorial Pacific over the next 9 months.

Sea surface temperature anomalies (°C) for September 2004

Mean sea surface temperatures (°C) for September 2004