
Number 107, August 2009
The Island
Climate Update
Collaborators
Pacific Islands National
Meteorological Services
Australian Bureau of
Meteorology
Meteo France
NOAA National
Weather Service
NOAA Climate
Prediction Centre
(CPC)
International Research
Institute for Climate
and Society
European Centre
for Medium Range
Weather Forecasts
UK Met Office
World Meteorological
Organization
MetService of
New Zealand
July’s climate
•
The South Pacific Convergence Zone (SPCZ) was positioned
southwest of normal, and contracted toward Papua New Guinea.
•
Suppressed convection in the central part of the Southwest Pacific
near Tokelau.
•
Mostly well above normal rainfall for many parts of New Caledonia
and the Solomon Islands.
El Niño/Southern Oscillation (ENSO), seasonal
rainfall, and sea surface temperature forecasts
•
El Niño conditions exist in the equatorial Pacific, but region-wide
atmospheric anomalies typical of El Niño are not as prominent.
Many dynamical climate models project the continuation of El Niño
through 2009.
•
Below normal rainfall is forecast for Tokelau, the Marquesas and the
Northern Cook Islands.
•
Above normal rainfall is expected for Western Kiribati. Near or
above normal rainfall is forecast for Eastern Kiribati, the Southern
Cook Islands, and the Austral Islands.
•
Above normal SSTs are forecast for Eastern Kiribati. Normal
or above normal SSTs are forecast for Papua New Guinea, the
Solomon Islands, Western Kiribati, the Northern Cook Islands and
the Austral Islands. Near normal SSTs are expected elsewhere in the
southwest Pacific.

The Island Climate Update, No. 107, August 2009
Page 2
Climate developments in July 2009
Outgoing Long-wave Radiation (OLR) anomalies, in Wm
2
are represented
by hatched areas. High radiation levels (yellow) are typically associated
with clearer skies and lower rainfall, while cloudy conditions lower the
OLR (blue) and typically result in higher rainfall. The July 2009 position
of the South Pacific Convergence Zone (SPCZ) was displaced southwest
of its normal position, less extensive, and weakly coherent compared
to previous months. The average position of the SPCZ is identified by
the dashed green line, which is based on mean January rainfall for the
South Pacific. Mean sea level (MSL) pressure anomalies (in hPa) are
shown as solid and dashed black lines.
-90 -70 -50 -30 -20 -10 10 20 30 50 70 90
Australia
NewZealand
Fiji
NewCaledonia
Vanuatu
Solomon Is
Pitcairn
Samoa
Tonga
Niue
EKiribati
Papua NewGuinea
NCook Is
S Cook Is
Society Is
WKiribati
LineIs
Tuvalu
Marquesas Is
Austral Is
Marshall Is
Rawaki Is
Tokelau Is
Nauru
FedStates of Micronesia
TuamotuIs
EQUATOR
Wallis & Futuna
Soil moisture in July 2009
Estimated soil moisture conditions at the end of July 2009, using
monthly rainfall data. Soil moisture projections for individual Pacific
Island countries are dependent on data availability at the time of
publication.
E
stimates of soil moisture shown in the map (right) are
based on monthly rainfall for one station in each country.
Currently there are not many sites in the water balance model,
but more stations will be included in the future.
The information displayed is based on a simple water balance
technique to determine soil moisture levels. Addition of
moisture to the available water already in the soil comes
from rainfall, with losses via evapotranspiration. Monthly
rainfall and evapotranspiration are used to determine the
soil moisture level and its changes. These soil moisture
calculations were made at the end of the month, and for
practical purposes, generalisations were made about the
available water capacity of the soils at each site.
Hanan (Niue), Apia (Samoa), Port Vila (Vanuatu), Tarawa
(Western Kiribati) and Fua’amotu (Tonga) project moist soil
moisture conditions. Raratonga (Southern Cook Islands) and
Nadi (Fiji) project moderate soil moisture at this time.
T
he South Pacific Convergence Zone (SPCZ) was displaced
slightly southwest of its normal position last month, and
contracted toward the Equator. Convection intensified near
the Federated States of Micronesia and northern Papua New
Guinea and enhanced rainfall was also observed over Nauru
and Western Kiribati during July. Suppressed convection
existed southeast of Western Kiribati last month and near
Tokelau. The regional circulation in July was characterised
by more frequent low pressure over the Equator near Eastern
Kiribati, south of the Austral Islands, and east of New Zealand.
This pattern resulted in more frequent easterly anomalies in
the northern Tuamotu Archipelago region and the Marquesas,
with westerlies being more frequent in the Austral Islands.
Most stations in Papua New Guinea and New Caledonia
received well above normal rainfall in July. High rainfall
was also recorded in the Solomon Islands, the southern
half of Vanuatu, most of Samoa, and in Western Kiribati.
For Western Kiribati this is the second month in a row with
considerable rainfall, and a break from drought conditions
that persisted in the southern part of that island group during
previous months. In addition, there were only three days in
July without rain at Tarawa. In contrast to last month in Fiji,
only three sites (Nadi, Lakita, and Rarawai) reported for the
ICU had well above average rainfall, while 19 other sites
received above normal rainfall for the month.
Drier than normal conditions occurred over much of the
central and eastern regions of the South Pacific during
July. Low rainfall totals in Tonga occurred at Niuafo’ou and
Mata’aho, which received 23% and 15% of normal rainfall,
respectively. There were also dry conditions in northern
Vanuatu (Sola and Pekoa), and in the Tuamotu Archipelago
and parts of the Society Islands, with less than 50% of
normal rainfall recorded in Gambier. Near normal rainfall
was recorded for Bora Bora.
Warmer than normal conditions occurred as a whole across
French Polynesia during July, with +0.5°C to +1.4°C
above normal temperatures recorded. A new monthly
mean temperature was also recorded for July at Faa’a, and
a maximum daily temperature of 26.9°C was recorded
at Rikitea. Across the Southwest Pacific in Australia, air
temperatures were 1–2 °C above average in northern regions
of the continent.
Wet
Moderate
Dry
Wet
Moderate
Dry
Wet
Moderate
Dry
Wet
Moderate
Dry
July 2009
July 2008
Island Group
Location
Rainfall
(mm)
% of
avg
Comments
Australia
Townsville
0.2
1
Very low
Solomon Islands Munda
591
184
Highest monthly
total in the region
New Caledonia
Moue
220
259
Very high
Papua New
Guniea
Kavieng
564
239
Very high
Takaroa
Tuamotu
34
41
Very low
Australia
New Zealand
Fiji
New Caledonia
Vanuatu
Solomon Is
Samoa
Tonga
Niue
E Kiribati
Papua New Guinea
S Cook Is
N Cook Is
Society Is
W Kiribati
Line Is
Tuvalu
Marquesas Is
Austral Is
Marshall Is
Rawaki Is
Tokelau Is
Nauru
Fed. States of
Micronesia
Tuamotu Is
Pitcairn
EQUATOR
July 2008
July 2007
Wet
Moderate
Dry
Wet
Moderate
Dry

The Island Climate Update, No. 107, August 2009
Page 3
Mean sea surface temperatures (ºC) for July 2009
Sea surface temperature anomalies (ºC) for July 2009
Forecast validation: May to July 2009
-3.0
-2.0
-1.0
0.5
1.5
2.5
Australia
New Zealand
Fiji
New Caledonia
Vanuatu
Solomon Is
Samoa
Tonga
Niue
E Kiribati
Papua New Guinea
S Cook Is
N Cook Is
Society Is
W Kiribati
Line Is
Tuvalu
Marquesas Is
Austral Is
Marshall Is
Rawaki Is
Tokelau Is
Nauru
Fed States of Micronesia
Tuamotu Is
Pitcairn
EQUATOR
Wallis & Futuna
10 12 14 16 18 20 22 24 26 28 30 32
Australia
New Zealand
Fiji
New Caledonia
Vanuatu
Solomon Is
Samoa
Tonga
Niue
E Kiribati
Papua New Guinea
S Cook Is
N Cook Is
Society Is
W Kiribati
Line Is
Tuvalu
Marquesas Is
Austral Is
Marshall Is
Rawaki Is
Tokelau Is
Nauru
Fed States of Micronesia
Tuamotu Is
Pitcairn
EQUATOR
Wallis & Futuna
El Niño/Southern Oscillation (ENSO)
D
uring July, conditions in the equatorial Tropical
Pacific indicated that the ocean moved into an
El Niño state, but the atmosphere has yet to respond.
Sea surface temperature anomalies in the equatorial
Pacific are generally positive and are broadly consistent
with El Niño conditions. NINO 3 & 4 anomalies for
July were +1.4°C and +0.8°C, respectively (3-month
means +1.0°C and +0.6°C). Subsurface conditions are
also consistent with El Niño, with a substantial positive
heat content anomaly in the eastern Equatorial Pacific.
However, positive temperature and heat anomalies
extend right across the Pacific Basin, though cooling in
the far west occurred from mid–July.
The atmospheric circulation in the region does not yet
appear to be coupled with the ocean. The July SOI
reverted to positive values (+0.2 for the month) with
a three-month mean also near zero. OLR anomalies
show a region of enhanced convection about and
(mostly) west of the Date Line, and the TRMM ENSO
precipitation index is only weakly positive (around
+0.1). Significant positive zonal wind anomalies have
been evident over the western Pacific throughout July,
but have not yet penetrated east of the Date Line. The
MJO has been weak since late June, but an event may
develop in August
The global climate model ensemble assessed by NIWA
show almost all dynamical models with warm (El
Niño) conditions through the end of the year, while all
statistical models indicate neutral conditions through
October. The July NCEP ENSO discussion suggests
weak-moderate El Niño conditions through the rest
of 2009. The IRI summary estimates at least an 80%
probability of El Niño through the rest of the year. The
Bureau of Meteorology indicates that the ocean is in an
El Niño state and that the atmosphere is now moving in
that direction.
A
region of suppressed convection was forecast in the
southwest Pacific encompassing Tokelau, Tuvalu, and the
Northern Cook Islands, with below average rainfall expected
for those areas during May – July 2009. Near to below average
rainfall was expected for Eastern Kiribati and the Marquesas.
Near normal rainfall was forecast for Pitcairn Island and
Samoa. Enhanced convection was forecast for Papua New
Guinea and Vanuatu, Fiji, Niue, and the Southern Cook
Islands, with above average rainfall. New Caledonia, Tonga,
Wallis & Futuna, and the Austral Islands were expected to
receive near or above average rainfall. No clear precipitation
guidance was offered for the Western Kiribati, the Solomon
Islands, the Tuamotu Archepelago and the Society Islands
The May – July 2009 forecast validation was calculated for
13 island groups (two countries did not report rainfall values;
four were forecast as climatology and were unscorable).
The global island group ‘hit’ rate was 74%, 21% higher
than average for May forecasts, and 13% higher than the
average for all months combined. Rainfall was overprojected
for Vanuatu and the Southern Cook Islands, while it was
underprojected for Samoa.

The Island Climate Update, No. 107, August 2009
Page 4
Tropical Pacific rainfall – July 2009
Rainfall totalling 200% or more is considered well above average. Totals of 40% or less are normally well below average. Highlighted values are new
records.
Data are published as received and may be subject to change after undergoing quality control checks. N/A denotes data unavailability at the time of
publishing, and * denotes synoptic values.
Territory and
station station
name
July 2009
rainfall
total (mm)
July 2009
percent of
average
Australia
Cairns Airport
5
17
Townsville Airport
0
1
Brisbane Airport
4
6
Sydney Airport
53
42
Cook Islands
Penrhyn
N/A
N/A
Aitutaki
N/A
N/A
Rarotonga Airport
47
45
Fiji
Rotuma Island
251
108
Udu Point
65
73
Nadi Airport
74
164
Nausori
101
86
French Polynesia
Hiva Hoa, Atuona
103
66
Bora Bora
75
100
Tahiti – Faa’a
42
79
Tuamotu, Takaroa
34
41
Gambier, Rikitea
73
47
Tubuai
101
70
Rapa
203
81
Kiribati
Tarawa
226
144
Kanton
101
135
New Zealand
Kaitaia
145
87
Whangarei Airport
168
104
Auckland Airport
112
85
New Caledonia
Ile Art, Belep
76
52
Koumac
119
225
Ouloup
138
152
Ouanaham
188
186
Poindimie
174
135
La Roche
245
247
La Tontouta
161
252
Noumea
143
204
Moue
220
259
Niue
Hanan Airport
90
77
Liku
59
46
Territory and
station station
name
July 2009
rainfall
total (mm)
July 2009
percent of
average
North Tasman
Lord Howe Island
85
45
Norfolk Island
144
97
Raoul Island
69
41
Samoa
Faleolo Airport
114
134
Apia
163
142
Nafanua
175
84
Afiamalu
353
183
Alafua
196
143
Solomon Islands
Taro
321
N/A
Munda
591
184
Auki
387
175
Honiara
148
149
Henderson
153
153
Kira Kira
467
142
Santa Cruz, Lata
392
113
Tonga
Niuafo’ou
31
23
Mata’aho Airport
16
15
Lupepau’u
56
57
Salote Airport
100
111
Nuku’alofa
123
129
Fua’amotu Airport
189
172
Tuvalu
Nanumea
65
31
Nui Island
167
69
Funafuti
174
69
Nuilakita
255
128
Vanuatu
Sola
125
51
Pekoa
46
54
Lamap
116
122
Port Vila
144
212
Tanna/Whitegrass
110
Aneityum
198
185
Papua New Guinea
Port Moresby
10
37
Wewak
383
205
Kavieng
564
239

The Island Climate Update, No. 107, August 2009
Page 5
Rainfall outlook map for August to October 2009
Tropical rainfall and SST outlook: August to October 2009
NOTE: Rainfall and sea surface termperature estimates for Pacific Islands for the next three months are given in the tables below. The tercile probabilities (e.g.,
20:30:50) are derived from the averages of several global climate models. They correspond to the odds of the observed rainfall or sea surface temperatures being in
the lowest one third of the distribution, the middle one third, or the highest one third of the distribution. For the long term average, it is equally likely (33% chance)
that conditions in any of the three terciles will occur. *If conditions are climatology, we expect an equal chance of the rainfall being in any tercile.
D
uring August – October 2009, a region of suppressed
convection is likely in the southwest Pacific
encompassing Tokelau, the Northern Cook Islands, and the
Marquesas, with below average rainfall expected for those
areas. Near to below average rainfall is expected for Papua
New Guinea and the Society Islands. Near normal rainfall is
forecast for Niue, the Tuamotu Archipelago, New Caledonia,
and Pitcairn Island. Enhanced convection is likely along the
Equator extending from Western to Eastern Kiribati, and in
the area around the Southern Cook Islands and the Austral
Islands. These regions are expected to receive near or above
normal rainfall, with Western Kiribati forecast to receive
above normal rainfall. No clear precipitation guidance is
offered for Fiji, Vanuatu, Tuvalu, Tonga, Samoa, Wallis &
Futuna, and the Solomon Islands.
The global models have a exhibited an increase in the near
equatorial Pacific sea surface temperatures for the northwest
corner of the Southwest Pacific. For August – October 2009,
above average temperatures are forecast for Eastern Kiribati.
A region of near or above average sea surface temperatures
are forecast around Papua New Guinea, the Solomon Islands,
Western Kiribati, the Northern Cook Islands, the Marquesas
and the Society Islands. Near normal SSTs are forecast for
the remainder of the southwest Pacific.
The confidence in the multi-model ensemble forecast
skill for this seasonal rainfall outlook is moderately high
for most Pacific Island countries. In the past, the average
region-wide hit rate for rainfall forecasts issued in August
is 61%, equivalent to the long-term average for all months
combined. The SST forecast confidence is mostly high for
this period, but the greatest uncertainty localised around the
Marquesas and Eastern Kiribati.
Island Group
Rainfall Outlook
Outlook confidence
Kiribati (Western)
20:35:45 (Above)
Moderate
Austral Islands
25:35:40 (Near or Above)
Moderate-High
Cook Islands (Southern)
25:35:40 (Near or Above)
Moderate-High
Kiribati (Eastern)
25:35:40 (Near or Above)
Moderate-High
Pitcairn Island
30:40:30 (Near normal)
Moderate
New Caledonia
30:40:30 (Near normal)
High
Niue
30:40:30 (Near normal)
High
Tuamotu Islands
30:40:30 (Near normal)
Moderate
Solomon Islands
30:35:35 (Climatology)
Moderate
Wallis & Futuna
35:35:30 (Climatology)
Moderate
Fiji
35:35:30 (Climatology)
Moderate
Vanuatu
35:35:30 (Climatology)
Moderate
Tonga
35:35:30 (Climatology)
Moderate
Samoa
35:35:30 (Climatology)
Moderate
Tuvalu
35:35:30 (Climatology)
Moderate
Papua New Guinea
40:35:25 (Near or Below)
Moderate
Society Islands
40:35:25 (Near or Below)
Moderate
Marquesas
45:35:20 (Below)
Moderate
Cook Islands (Northern)
45:35:20 (Below)
Moderate-High
Tokelau
45:35:20 (Below)
Moderate-High
Australia
New Zealand
Fiji
New Caledonia
Vanuatu
Solomon Is
Pitcairn
Samoa
Tonga
Niue
E Kiribati
Papua New Guinea
N Cook Is
S Cook Is
Society Is
W Kiribati
Line Is
Tuvalu
Marquesas Is
Austral Is
Marshall Is
Rawaki Is
Tokelau Is
Nauru
Fed States of Micronesia
Tuamotu Is
EQUATOR
Wallis & Futuna
NO
FORECAST
SST outlook map for August to October 2009
Island Group
SST Outlook
Outlook confidence
Kiribati (Eastern)
20:35:45 (Above)
Moderate
Kiribati (Western)
25:35:40 (Near or Above)
Moderate-High
Austral Islands
25:40:35 (Near or Above)
High
Cook Islands (Northern)
25:40:35 (Near or Above)
High
Papua New Guinea
25:40:35 (Near or Above)
Moderate-High
Solomon Islands
25:40:35 (Near or Above)
Moderate-High
Cook Islands (Southern)
30:40:30 (Near normal)
High
Fiji
30:40:30 (Near normal)
High
Marquesas
30:40:30 (Near normal)
Moderate
New Caledonia
30:40:30 (Near normal)
High
Niue
30:40:30 (Near normal)
High
Pitcairn Island
30:40:30 (Near normal)
High
Samoa
30:40:30 (Near normal)
High
Society Islands
30:40:30 (Near normal)
High
Tokelau
30:40:30 (Near normal)
High
Tonga
30:40:30 (Near normal)
High
Tuamotu Islands
30:40:30 (Near normal)
High
Tuvalu
30:40:30 (Near normal)
High
Vanuatu
30:40:30 (Near normal)
High
Wallis & Futuna
30:40:30 (Near normal)
High
Australia
New Zealand
Fiji
New Caledonia
Vanuatu
Solomon Is
Pitcairn
Samoa
Tonga
Niue
E Kiribati
Papua New Guinea
N Cook Is
S Cook Is
Society Is
W Kiribati
Line Is
Tuvalu
Marquesas Is
Austral Is
Marshall Is
Rawaki Is
Tokelau Is
Nauru
Fed States of Micronesia
Tuamotu Is
EQUATOR
Wallis & Futuna
Below
Near or
Below
Near
Normal
Near or
Above
Above
NO
FORECAST
NO
FORECAST

The Island Climate Update, No. 107, August 2009
Page 6
Sources of South Pacific rainfall data
This bulletin is a multi-national project,
with important collaboration from the
following
Meteorological
Services:
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, Wallis and
Futuna.
Web links to ICU partners:
South Pacific Meteorological Services:
Cook Islands
http://www.cookislands.pacificweather.org/
Fiji
http://www.met.gov.fj
Kiribati
http://pi-gcos.org/index.php (follow link to PI Met
Services then Kiribati Met Service)
New Zealand
http://www.metservice.co.nz/
Niue
http://pi-gcos.org/index.php (follow link to to PI Met
Services then Niue Met Service)
Papua New Guinea
http://pi-gcos.org/index.php (follow link to to PI Met
Services then Papua New Guinea Met Service)
Samoa
http://www.mnre.gov.ws/meteorology/
Solomon Islands
http://www.met.gov.sb/
Tonga
http://www.met.gov.to/
Tuvalu
http://tuvalu.pacificweather.org/
Vanuatu
http://www.meteo.gov.vu/
International Partners
Meteo-France
New Caledonia: http://www.meteo.nc/
French Polynesia: http://www.meteo.pf/
Bureau of Meteorology (Australia)
http://www.bom.gov.au/
National Oceanographic and Atmospheric Administration
(USA)
National Weather Service: http://www.nws.noaa.gov/
Climate Prediction Center: http://www.cpc.noaa.gov/
The International Research Institute for Climate and
Society (USA):
http://portal.iri.columbia.edu/portal/server.pt
The UK Met Office
http://www.metoffice.gov.uk/
European Centre for Medium-term Weather Forecasts
http://www.ecmwf.int/
Cover Photo:
Wendy St George,
NIWA
Visit The Island Climate Update at:
www.niwascience.co.nz/ncc/icu
Your comments and ideas about The Island
Climate
Update are welcome. Please contact:
Dr Andrew Lorrey, NIWA,
41 Market Place, Auckland, New Zealand
E-mail:
a.lorrey@niwa.co.nz
Forecasts:
Dr. Andrew Lorrey (South Pacific rainfall
and SST forecasts) and the NIWA National
Climate Centre (ENSO wrap)
ICU Editors:
Andrew Lorrey Email:
a.lorrey@niwa.co.nz
James Renwick Email:
j.renwick@niwa.co.nz
Harriet Palmer Email:
h.palmer@niwa.co.nz
Acknowledgements
This bulletin is produced by NIWA and
made possible with financial support from
the New Zealand Agency for International
Development (NZAID), with additional
support from the Pacific Islands Applied
Geosciences Commission (SOPAC) and
the Secretariat for the Pacific Regional
Environmental
Programme
(SPREP).
This summary is prepared as soon as possible
following the end of the month, once the
data and information are received from
the Pacific Island National Meteorological
Services (NMHS). Delays in data collection
and communication occasionally arise. While
every effort is made to verify observational
data, NIWA does not guarantee the accuracy
and reliability of the analysis and forecast
information presented, and accepts no
liability for any losses incurred through
the use of this bulletin and its content.
The contents of The Island Climate
Update may be freely disseminated,
provided the source is acknowledged.
Requests for Pacific Island climate data
should be directed to the Meteorological
Services concerned.
The Island
Climate Update