October
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 25 – 8 October 2002
September’s Climate: A large area of very enhanced convection, associated with the now well-established El Niño, persists in the central equatorial Pacific. This resulted in enhanced rainfall from Nauru across to Eastern Kiribati, with totals at least 200% of average over much of that region, and more than 1000% of average in some areas. Rainfall was also above average in parts of Vanuatu, Fiji, Tonga and the Marquesas Islands. The SPCZ was near its average location about and west of the dateline, but had little activity further east. An area of divergence affected Indonesia, and extended over much of Papua New Guinea, and dry conditions extended from Australia across to New Caledonia. Willis Island, in the western Coral Sea, has now recorded 14 consecutive months with less than 75% of average rainfall. Rainfall was well below average from the Northern Cook Islands across to central French Polynesia.
ENSO and sea surface temperatures (SST): A more persistent El Niño state is now apparent, with anomalous westerlies affecting equatorial regions about and west of the dateline. The 3-month Southern Oscillation Index (SOI) remains steady at -1.2, and positive equatorial sea surface temperature (SST) anomalies around Kiribati intensified. The El Niño is expected to persist into early 2003.
Forecast validation: How well are we doing with our predictions?
Three month outlook: Above average rainfall is likely in both Western and Eastern Kiribati. Tuvalu and Tokelau are likely to experience average or above average rainfall. Below average or average rainfall is expected from Papua New Guinea across to the Southern Cook Islands including New Caledonia, Vanuatu and Fiji.
Feature Article: Relative Influences of the Interdecadal Pacific Oscillation and ENSO on the South Pacific Convergence Zone.
Sources of South Pacific rainfall data
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