Island Climate Update 42 - March 2004

26 March 2007 - 8:58am

Science Centres: Climate

March

Monthly climate

ENSO & SST

Forecast validation

Three-month outlook

Feature article

Data sources

Feature article
Pacific Island weather and the MJO Dr Mike Revell, NIWA The Madden-Julian Oscillation (MJO) is the major mode of variability of the tropical atmosphere-ocean system on time scales of 30 to 70 days. The MJO organizes convection into an eastward-propagating envelope of smaller-scale disturbances. This envelope moves eastward at between 5 and 10 ms-1 on average, generally forming in the tropical Indian Ocean and dissipating over the central Pacific. It is generally most active during the southern hemisphere summer and autumn.

Forecast validation
Forecast validation Forecast period: December 2003 to February 2004 Above average rainfall was expected for Western Kiribati with enhanced convection expected in the equatorial region extending from the Solomon Islands eastwards to Tokelau, Tuvalu and Wallis and Futuna. Below average rainfall was forecast for Eastern Kiribati, with average or below average rainfall in the Marquesas Islands. Rainfall was lower than expected in Tonga, central and southern French Polynesia region.

ENSO & SST
ENSO and Sea Surface Temperatures Western Pacific warmer than usual Average SSTs in NINO4 The equatorial Pacific remains in a neutral state. Equatorial SSTs have eased further, but are slightly higher than normal, especially in the west. The monthly SOI continues to fluctuate, associated with the Madden-Julian Oscillation (MJO). The mean SOI for February was +0.7, and +0.1 for December to February. The NINO3 SST anomaly for February was about +0.2°C and NINO4 about +0.6°C (December to February are +0.5°C and +0.8°C, respectively).

March
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 42 – 5 March 2004 February’s climate: Tropical cyclone ‘Ivy’, the second this season, brought severe winds and heavy rainfall to parts of Vanuatu on the 25 – 26th of February. The South Pacific Convergence Zone (SPCZ) was located further south than usual in many areas, with above average rainfall over much of Fiji and the Southern Cook Islands.

Monthly climate
Climate developments in February 2004 SPCZ was further south than usual Above average rainfall in parts of Fiji, Vanuatu and the Southern Cook Islands An extensive region of below average rainfall from Western Kiribati to Pitcairn Island The Southwest Pacific OLR/rainfall anomaly pattern changed again, withthe February patterns almost opposite that of January. The SPCZ was located further south than usual in many areas, extending east-southeast from the Solomon Islands toward Fiji, across to Samoa, and over the Southern Cook Islands.

Three-month outlook
Rainfall outlook for March to May 2004 Enhanced convection in Western Kiribati, Vanuatu, the Wallis and Futuna, and the Society Islands Average or below average rainfall likely over the Tuamotu Islands and Pitcairn Island Below average rainfall is expected in the Marquesas Islands Enhanced convection is expected in Western Kiribati, Vanuatu, Wallis and Futuna and the Society Islands, resulting in average or above rainfall around this region.

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