Island Climate Update 16 - January 2002

Tropical Cyclones
By Stuart Burgess, Dr Jim Renwick and Dr Jim Salinger, NIWA
Three tropical cyclones so far
The tropical cyclone season is now well underway, with three cyclones having occurred so far this season. ‘Trina’ occurred from 30 November through 2 December, affecting the Southern Cook Islands. Winds gusted to 104 km/h at Rarotonga Airport, and floods resulted because of heavy rainfall.

Forecast validation
Forecast period: October to December
Areas of average to above average rainfall were expected from Papua New Guinea southeast to the Austral Islands of French Polynesia, as well as western Kiribati. Average to below average rainfalls were forecast for Tuvalu to the Marquesas, including the Samoa, Tokelau, Eastern Kiribati, the Northern Cooks, and Pitcairn Island.

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.

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 16 – 10 January 2002
December's Climate: The South Pacific Convergence Zone was very active bringing high rainfall to many islands from north of Papua-New Guinea, east through Nauru, Western Kiribati, Tuvalu and Tokelau, and southeast to the Northern Cook Islands and much of French Polynesia. Rainfall was also high over Samoa, northern Tonga, and the North Island of New Zealand.

Climate developments in November 2001
Very active SPCZ brings high rainfall to many islands
Low rainfall from coastal Queensland in Australia, across to Vanuatu
A very strong El Niño-like OLR/rainfall anomaly pattern was evident in December in the west of the region, as a broad band of enhanced convection occurred in equatorial regions from north of Papua-New Guinea east through Nauru, Western Kiribati, Tuvalu and Tokelau, and southeast to the Northern Cook Islands and much of French Polynesia.

Rainfall outlook for January to March 2002
SPCZ more active than usual
Above average to average rainfall in western equatorial latitudes southeast to Samoa, Tonga and Niue: average to below average rainfall in the equatorial east, and from northern Queensland across to Vanuatu
The trade winds are now only slightly enhanced east of the dateline, having weakened to the west with westerly wind anomalies. Thus the SPCZ is now displaced further north of its normal location for the time of year, and is expected to be active during the next few months.

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