Island Climate Update 43 - April 2004

26 March 2007 - 8:58am

Science Centres: Pacific Rim

April

Monthly climate

ENSO & SST

Forecast validation

Three-month outlook

Feature article

Data sources

April
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 43 – 6 April 2004 March’s climate: Tropical cyclone ‘Grace’, only the 3rd this season, formed in the Coral Sea, west of New Caledonia from 21 to 22 March. A large region of enhanced convergence and high rainfall persists west of the Date Line. The South Pacific Convergence Zone (SPCZ) was located further north and east than usual.

Feature article
Ocean signals after the 1997–98 El Niño Dr Melissa Bowen and Dr Phil Sutton, NIWA A series of warm events occurred in the Southwestern Pacific after the unusually strong 1997-98 El Niño. In 1998, record sea surface temperatures were measured around New Zealand, coral bleaching took place on the Great Barrier Reef, and a warming trend in the Tasman Sea increased. At the beginning of 1998, a region of elevated sea surface temperature formed, stretching southwest from the Queensland coast past New Zealand (Fig. 1). These elevated temperatures persisted for most of 1998.

Forecast validation
Forecast validation Forecast period: January to March 2004 Enhanced convection with above average or average rainfall was expected in parts of the tropical Southwest Pacific from the Solomon Islands extending east to the Austral Islands, including Samoa, the Northern Cook Islands and the Society and Austral Islands. Below average rainfall was predicted for the Marquesas Islands.

ENSO & SST
ENSO and Sea Surface Temperatures SOI near zero Equatorial SST anomalies are near zero The equatorial Pacific is in a neutral state. Equatorial SST anomalies are near zero, but continue slightly positive in the far west. The monthly and seasonal SOI values are near zero. The NINO3 SST anomaly for March was about +0.2°C and NINO4 about +0.3°C (January to March are +0.3°C and +0.6°C, respectively). A Madden-Julian Oscillation (MJO) event induced westerly wind anomalies in the western Pacific from mid-March but the trade winds are otherwise near normal.

Monthly climate
Climate developments in March 2004 In March a large region of enhanced convergence persisted over the Caroline Islands, Papua New Guinea, northern Australia, and the Solomon Islands, extending into the Coral Sea (with rainfall exceeding 400 mm at many locations).

Three-month outlook
Rainfall outlook for April to June 2004 Above average rainfall over the Solomon Islands Suppressed convection in the equatorial eastern Pacific – Eastern Kiribati, the Marquesas Islands and parts of central French Polynesia Enhanced convection is expected with above average rainfall over the Solomon Islands and average or above average rainfall in Papua New Guinea and Western Kiribati. Another smaller region of enhanced convection is expected near the Date Line resulting in average or above average rainfall in Tonga and Niue.

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