Island Climate Update 49 - October 2004

ENSO Update
Current oceanic observations show El Niño/Southern Oscillation (ENSO) characteristics in the tropical Pacific region which are not coupled with the atmosphere
In July 2004, the tropical Pacific showed mixed warming and cooling signals, and Southern Oscillation Index (SOI) fluctuations occurred from April 2004. The equatorial sea surface temperature (SST) anomalies were below average near the South American coast but above average over the remainder of the equatorial tropical Pacific east of the Date Line. These were more than 1°C above average near the Date Line.

ENSO and Sea Surface Temperatures
Despite the equatorial Pacific sea surface and subsurface temperatures being in an El Niño state, the atmosphere is yet to respond to the oceanic signals. The Southern Oscillation Index (SOI) weakened during September to -0.4, with the three month mean (July to September) at -0.7. Equatorial sea surface temperature (SST) anomalies rose compared to August. The NINO3 average anomaly was +0.9°C (August was +0.6°C) and July to September mean was +0.6°C.

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 49 – October 2004
September’s climate: The South Pacific Convergence Zone (SPCZ) extended from Papua New Guinea to Rotuma Island (Fiji). Convergence also occurred south of Fiji east to the Southern Cook Islands. High rainfall persisted throughout much of Tonga. Below average rainfall occurred in Vanuatu, New Caledonia, central and southern French Polynesia and Pitcairn Island.

Tropical pacific rainfall - September 2004

Territory and station name
September 2004 rainfall total (mm)
Long-term average (mm)
September 2004 percent of average
Lowest on record (mm)
Highest on record (mm)
Records began

Australia

Cairns Airport
6.4
36
18
0
103
1941

Townsville Airport
6.2
11
56
0
81
1940

Brisbane Airport
31.0
35
89
0
104
1929

Sydney Airport
79.4
63
126
2
249
1929

Cook Islands

Rarotonga Airport
288.7
109
265
13
268
1929

Fiji

Rotuma
324.7
238
136
48
899
1912

Nadi
72.2
70
103
0
279
1942

Nausori
146.8
165
89
12
473
195