ENSO & SST

ENSO and Sea Surface Temperatures

Seas continue warming in the west

SST anomalies were still weak across the Equatorial Pacific, but the cooler east- warmer west temperature gradient remained. SST models showed positive anomalies building in the west around the Solomon Islands and Vanuatu (to at least 1.0°C above average), and particularly around New Caledonia (at least 1.5°C above average). Anomalies continued above average east of the Tuamotu Islands and around Pitcairn Island. The warmest surface waters (30-31°C) occurred around the Solomon Islands. Significant cooling occurred between Tonga and the Austral Islands, with SST anomalies more than 1.5°C below average around the Southern Cooks. Although equatorial SST anomalies are generally weak and are expected to stay in the neutral range for a few more months, five of twelve global SST forecast models show indications of an evolution towards weak warm ENSO conditions in the months just following the southern hemisphere wet season, although forecast confidence is presently low. The December Southern Oscillation Index (SOI) fell to -1.2 (because of negative pressure anomalies over Tahiti); the 3-month mean was -0.3, still in the neutral range. The trade winds are now only slightly enhanced in the central Equatorial Pacific, with westerly anomalies in the west.

Sea surface temperature anomalies (°C) for December 2001

Mean sea surface temperatures (°C) for December 2001