Island Climate Update 110 - November 2009

The equatorial Pacific Ocean remains in an El Niño state, and during October (especially in the last two weeks of the month) the atmosphere appeared to have started responding to the ocean. Equatorial sea surface temperature anomalies are positive across much of the Pacific, with the largest anomalies now in the central Pacific, in and near the NINO4 region. NINO 3 & 4 anomalies were +0.9 °C and +1.2 °C in October (3–month ASO means +1.1 °C and +1.0 °C).

During August – October 2009, a region of suppressed convection was forecast for the southwest Pacific encompassing Tokelau, the Northern Cook Islands, and the Marquesas. Below average rainfall was expected for those areas. Near to below average rainfall was expected for Papua New Guinea and the Society Islands.
Near normal rainfall was forecast for Niue, the Tuamotu Archipelago, New Caledonia, and Pitcairn Island. Enhanced convection was forecast along the Equator extending from Western to Eastern Kiribati, and in the area around the Southern Cook Islands and the Austral Islands.

Number 110 - November 2009
October’s climate
South Pacific Convergence Zone (SPCZ) is contracted toward Papua New Guinea, and shows north-eastward movement to the east of the Date Line.
Enhanced convection exists about the Equator from Western Kiribati to Eastern Kiribati.
Below normal rainfall for several stations in Fiji, New Caledonia, Vanuatu, Niue, Tonga, and in parts of Australia occurred in October, but very high rainfall was recorded in the Solomon Islands and French Polynesia.
El Niño/Southern Oscillation (ENSO), seasonal rainfall, and sea surfacetemperature forec

Estimates of soil moisture shown in the map (right) are based on monthly rainfall for one station in each country. Currently there are not many sites in the water balance model, but it is planned to include more stations in the future.
The information displayed is based on a simple water balance technique to determine soil moisture levels. Addition of moisture to the available water already in the soil comes from rainfall, with losses via evapo-transpiration. Monthly rainfall and evapo-transpiration are used to determine the soil moisture level and its changes.

A region of suppressed convection is likely in the southwest Pacific encompassing Samoa, Niue, Tonga, Fiji, New Caledonia, the Southern Cook Islands, the Society Islands, the Austral Islands and Papua New Guinea. Near to below average rainfall is expected for all of those islands, except for Samoa, which is expected to receive below average rainfall. Near normal rainfall is forecast for the Northern Cook Islands, the Tuamotu Archipelago, and Pitcairn Island.