Science Centres: Pacific Rim

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 23 – 7 August 2002

July’s Climate: The South Pacific Convergence Zone (SPCZ) extended east from the Solomon Islands to the north of Samoa, being displaced south of its mean position. It continued to be weak with little activity further east in the Southwest Pacific. A large area of enhanced convection extended from the region south of the Solomon Islands, across Fiji, Samoa, Tonga and Niue, some locations recording more than 200% of average rainfall. Rainfall was also above average in the Marquesas Islands of northern French Polynesia. An extensive region of divergence with generally below average rainfall extended from the region east of the Solomon Islands eastward to Tokelau, including Kiribati. Rainfall was also below average from Eastern Kiribati south to the Cook Islands, and Society Islands of French Polynesia. Below average rainfall occurred over much of Australia, extending across to New Caledonia. Willis Island has now recorded 12 consecutive months with less than 75% of average rainfall. Mean air temperatures were average or above average over much of our forecast region. However, they were below average throughout much of New Caledonia.

ENSO and sea surface temperatures (SST): Although present conditions in the Pacific show some El Niño like patterns, a more consistent and organised pattern is yet to be established. It is likely to be a weak to moderate event. The Southern Oscillation Index remains negative and the equatorial Pacific Ocean continues to be warmer than average.

Forecast validation: How well are we doing with our predictions?

Three month outlook: French Polynesia are likely to experience average or above average rainfall. Average or below average rainfall is expected in Papua New Guinea, New Caledonia, Samoa, Cook Islands and northern parts of the French Polynesia.

Feature Article: Interdecadal Pacific Oscillation – Modulating ENSO

Sources of South Pacific rainfall data

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