Island Climate Update 83 - August 2007

Reviving of rainfall stations in Vanuatu
Figure 1: Average rainfall rate for March and December
Figure 2: Annual average rainfall rate from TRMM 0.25 degree analysis for 2006
Dr Brett Mullan, NIWA
Three convergence zones can be identified in the Pacific: the Intertropical Convergence Zone (ITCZ) in the Northern Hemisphere at around 5–10°N; its Southern Hemisphere counterpart, denoted separately here as SITCZ; and the South Pacific Convergence Zone (SPCZ) that extends diagonally from around Solomon Islands (10°S, 160°E) to near 30°S, 140°W.

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 83 – August 2007
July’s climate
South Pacific Convergence Zone (SPCZ) fairly in east inactive; suppressed convection persists along the equator
Rainfall above average throughout much of Vanuatu; below average in parts of Southern French Polynesia, and over much of Kiribati and New Caledonia
Much warmer than normal in Fiji, Tuvalu, Wallis and Futuna, and the Southern Cook Islands
El Niñ

Climate developments in July 2007
Outgoing Long-wave Radiation anomalies for July 2007. (Click for enlargement and detail)
The South Pacific Convergence Zone (SPCZ) affected the Solomon Islands (closely linked to the monsoon trough north of Papua New Guinea) and Vanuatu, with little activity east of the Equator. Convergence was weakly enhanced south of Fiji and over New Zealand’s North Island, due to frequent depressions in the Tasman Sea.

Three-month outlook: August to October 2007
 
Rainfall outlook map for August to October 2007.

Tropical Pacific rainfall - July 2007
Territory and station name
July 2007 rainfall
total (mm)
July 2007 percent
of average
Australia
Cairns Airport
21.8
75
Townsville Airport
0.2
1
Brisbane Airport
0.8
1
Sydney Airport
35.2
28
Cook Islands
Penrhyn
149.6
108
Rarotonga Airport
17.4
17
Rarotonga EWS
14.4
14
Fiji
Rotuma
207.2
89
Udu Point
125.3
141
Nadi
69.5
154
Nausori
158.2
134
Ono-I-Lau
155.8
169
French Polynesia
Hiva Hoa, Atuona
128.8
83
Bora Bora Motu
40.0
53
Tahiti – Faa’a
30.0
57
Tuamotu, Takaroa
157.2
195
Gambier, Ri

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 produced by NIWA and made possible with financial support from the New Zealand Agency for International Development (NZAID), with addi