Island Climate Update 39 - December 2003

23 March 2007 - 2:22pm

Science Centres: Pacific Rim

December

Monthly climate

ENSO & SST

Forecast validation

Three-month outlook

Feature article

Data sources

Feature article
Defining ENSO Events Dr Brett Mullan, NIWA Given the very wide interest in the climate impacts of El Niño-Southern Oscillation (ENSO), it is perhaps surprising that there is no universally accepted definition of an ENSO event. There is certainly qualitative agreement on typical characteristics associated with El Niño and La Niña periods.

Forecast validation
Forecast validation Forecast period: September to November 2003 Average or above average rainfall was expected in Papua New Guinea, but suppressed convection in equatorial regions was expected to result in average or below average rainfall in Western and Eastern Kiribati and the Marquesas Islands. Rainfall was also expected to be average or below average in Tuvalu and Fiji.

December
An overview of the present climate in the tropical South Pacific Islands, with an outlook for the coming months, to assist in dissemination of climate information in the Pacific region. Number 39 – 5 December 2003 November’s climate: Below average rainfall persisted over much of the equatorial Southwest Pacific, with suppressed convection over much of Western and Eastern Kiribati, Tokelau, and also parts of northern French Polynesia. Rainfall was also below average over the southern Coral Sea, and parts of New Caledonia, Fiji, and Niue.

ENSO & SST
ENSO and Sea Surface Temperatures Warmer SSTs in western equatorial Pacific Neutral ENSO state forecast till April 2004 The Equatorial Pacific is in a neutral state, but equatorial SSTs remain higher than normal, especially just west of the Date Line. The NINO3 SST anomaly for November is about +0.6°C and NINO4 is above +1.1°C (3-month means are +0.6°C and +0.9°C, respectively). Despite the relatively high SST anomalies, zonal winds have been near-normal in the Equatorial Pacific recently, after a period of westerly anomalies in the west.

Monthly climate
Climate developments in November 2003 Below average rainfall persists over much of the equatorial Southwest Pacific Enhanced convection from the Caroline Islands to southern Vanuatu High rainfall persists in Pitcairn Island A large region of suppressed convection and generally below average rainfall encompassed much of Western and Eastern Kiribati, Tokelau, and parts of northern French Polynesia. Rainfall was also below average (75% of average) over the southern Coral Sea, and parts of New Caledonia, Fiji, and Niue.

Three-month outlook
Rainfall outlook for December 2003 to February 2004 Average or above average from Western Kiribati southeast to the Tuamotu Islands Trending below average in New Caledonia, Eastern Kiribati and the Marquesas Islands Enhanced convection is expected in the equatorial region just west of the Date Line, resulting in average or above average rainfall from Western Kiribati across to the Tuamotu Islands, including the Solomon Islands, Tuvalu, Tokelau and Wallis and Futuna. Average or below average rainfall is forecast for New Caledonia and the Marquesas Islands.

Data sources
Sources of South Pacific rainfall data This bulletin is a multi-national project with important collaboration from the following Pacific nations: American Samoa Australia Cook Islands Fiji French Polynesia Kiribati New Caledonia New Zealand Niue Papua New Guinea Pitcairn Island Samoa Solomon Islands Tokelau Tonga Tuvalu Vanuatu Requests for Pacific island climate data should be directed to the Meteorological Services concerned. Acknowledgements This bulletin is made possible with financial support from the New Zealand Agency for International Development (NZAID), Wellington, New Zealand, wi