Number 103, April 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
March’s climate
•
The South Pacific Convergence Zone (SPCZ) was displaced
southwest of its normal position and was very active.
•
Very suppressed convection near Western Kiribati and south of the
Equator from Nauru southeast to Tuvalu.
•
Mostly well above normal rainfall for French Polynesia and New
Caledonia.
El Niño/Southern Oscillation (ENSO), seasonal
rainfall, and sea surface temperature forecasts
•
La Niña-like conditions exist in the tropical Pacific, but have
weakened relative to previous months. Most climate models project
ENSO neutral conditions for autumn and winter 2009.
•
Below normal rainfall is forecast for Tuvalu, Tokelau, and the
Northern Cook Islands.
•
Above normal rainfall is expected for Vanuatu, Fiji, Niue, the
Southern Cook Islands, and Papua New Guinea.
•
SST anomalies are expected to weaken in the region. Normal to
above normal SSTs are forecast for the southwestern half of the
southwest Pacific region. Normal to below normal SSTs are forecast
for the northeast half of the southwest Pacific.
The Island Climate Update, No. 103, April 2009
Page 2
Climate developments in March 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 March 2009
position of the South Pacific Convergence Zone (SPCZ) was displaced
southwest of its normal position, and exhibited coherent regions of
low and high values similar to month. 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 grey 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
Line Is
Tuvalu
Marquesas Is
Austral Is
Marshall Is
Rawaki Is
Tokelau Is
Nauru
Fed States of Micronesia
Tuamotu Is
EQUATOR
Wallis & Futuna
Soil moisture in March 2009
Estimated soil moisture conditions at the end of March 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.
Nadi (Fiji), Hanan (Niue), Rarotonga (Southern Cook Islands),
and Apia (Samoa) project moist (at or near field capacity) soil
moisture conditions. Soils are moderate for the time of year
at Kanton (Kiribati) and Fua’amotu (Tonga).
T
he South Pacific Convergence Zone (SPCZ) was displaced
south and west of normal during March, continuing the
trend from last month. A region of enhanced rainfall, partly
due to intensified convection, was observed over Papua
New Guinea and New Caledonia last month. Suppressed
convection intensified during near the Equator during March
and encompassed the region northeast of the Solomon
Islands, including Western Kiribati, Nauru, and Tuvalu.
Significant drought has developed for some of the southern
islands in Western Kiribati group, particularly at Banaba.
There was also suppressed convection localised near the
Pitcairn Islands. The regional circulation was characterised
by more frequent high pressure in the North Tasman Sea,
and lower than normal pressures to the northeast of New
Zealand, over the Southern Cook Islands, and near New
Caledonia.
There were many high precipitation totals during March,
particularly in French Polynesia where all stations recorded
between 140–270% of normal rainfall. In New Caledonia,
with the exception of Belep (22% of normal) all stations had
well above normal rainfall, with record highs at Koumac and
Poindimie. These high rainfall totals were due to the position
of the SPCZ near New Caledonia, and also because of the
passage of Tropical Cyclone Jasper close to the island on 24
March. There was also a record high rainfall total at Hanan
Airport in Niue (see table below). In general, the Solomon
Islands had near normal or above normal rainfall for the
month, except at Lata.
In contrast to last month when Townsville, Australia received
a new monthly high rainfall total of 989 mm (339 % of
normal), only 18mm of rainfall (8% of normal) fell at that
location. In general, normal or below normal rainfall occurred
in the central, northwestern, and northeastern parts of the
Southwest Pacific during March. Record low rainfall totals
were recorded in Tonga and Tuvalu (see table below). Low
monthly rainfall totals also occurred in the Northern Cook
Islands, Eastern and Western Kiribati, Pitcairn Island, and the
northern part of Fiji and Rotuma.
Northern New Zealand experienced a relatively dry month,
with the northern part of the country recording normal to
below normal rainfall (40–90% of normal). The North
Wet
Moderate
Dry
Wet
Moderate
Dry
Wet
Moderate
Dry
Wet
Moderate
Dry
March 2009
March 2008
Island Group
Location
Rainfall
(mm)
% of
avg
Comments
New Caledonia
Koumac
397
263
Record high
New Caledonia
Poindimie
891
223
Record high;
Highest monthly
total in the region
Niue
Hanan
380
182
Record high
Tonga
Salote
52
23
Record low
Tuvalu
Niulakita
84
23
Record low
Tasman Region, including Raoul Island and Norfolk Island,
was also relatively dry during March.
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. 103, April 2009
Page 3
Mean sea surface temperatures (ºC) for March 2009
Sea surface temperature anomalies (ºC) for March 2009
Forecast validation: January to March 2009
-3
-2
-1
0.5
2
3
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 March, previous La Niña conditions seen
in the equatorial Pacific since December 2008
are now weakening towards the borderline of neutral.
The SOI, which was +1.4 in February, dropped to
+0.2 by the end of March (January–March mean
+0.9). Easterly trade winds are now close to normal
across much of the equatorial Pacific, although a
westerly burst appeared late in March west of the
Dateline
SST anomalies across much of the equatorial Pacific
have eased a little. NINO3 and NINO4 anomalies
are –0.7°C and –0.4°C respectively (both around
–0.7°C in February). Sea surface height anomalies
still show a clear La Niña pattern with positive heights
west of the Dateline. Negative subsurface oceanic
heat content anomalies (average temperatures in
the upper 300m of the ocean), and temperature
anomalies at thermocline depth continue to weaken
slowly across the eastern half of the Pacific. Tropical
Pacific convection and precipitation was suppressed
near the Date Line just south of the Equator, about
Indonesia and northern Australia, and was enhanced
across the northern hemispheric tropics at the
Australian longitudes during March. The TRMM
ENSO precipitation index was –1.6 as of 24 March.
The MJO is presently weak and is expected to
strengthen in early April, resulting in suppressed
convection over the eastern Indian Ocean.
The global climate model ensemble assessed by
NIWA indicate neutral ENSO conditions for April
–June, and all but two models indicate neutral
conditions in July–September. The NCEP discussion
of 5 March indicates La Niña conditions will
gradually weaken with more than a 50% chance of
ENSO–neutral conditions in the coming months.
The IRI summary of 19 March indicates a 50 %of
La Niña conditions persisting through to end of May
reducing to 25–30 percent for May–July as near-
neutral conditions become most likely.
A
region of suppressed convection was forecast for
January–March 2009 over the central and eastern
Southwest Pacific, extending from Western Kiribati to
Eastern Kiribati, including Tuvalu, Tokelau, the Northern
Cook Islands, and the Tuamotu archipelago. Below normal
rainfall was expected for those island groups. Near–to–
below normal rainfall was expected for Samoa. Enhanced
convection was expected to extend southeast from Vanuatu
and New Caledonia, to the Austral Islands, including Tonga,
Fiji, the Southern Cook Islands and Niue, with average to
above or above average rainfall for those island groups. No
precipitation guidance was offered for Pitcairn Island, Papua
New Guinea, the Solomon Islands, the Marquesas, or the
Society Islands for January–March 2009.
The validation for the January – March 2009 forecast was
calculated for 13 island groups (three countries did not report
rainfall values; three were forecast as climatology and were
unscorable). The global island group ‘hit’ rate was 64%,
7% higher than average for January and 3% higher than the
average for all months combined. Rainfall was overprojected
for the Southern Cook Islands and Austral Islands.
Tropical Cyclone Activity and Guidance
F
our Tropical Cyclones (TC) affected the Southwest Pacific region during March. TC Hamish formed off the Australian
coast in the Coral Sea on March 5. TC Joni followed, forming on March 11 near the Southern Cook Islands and attained
a maximum intensity of 55 knots. Damage in the Southern Cooks, if any, was minimal. TC Ken then formed between Niue
and the Southern Cook Islands on March 17 and attained a maximum intensity of 50 knots. TC Ken did not affect land areas.
TC Jasper entered the RSMC Nadi region of responsibility from the Coral Sea on March 24 as a tropical cyclone with storm
intensity and later passed through New Caledonia’s waters, with no significant damage reported.
The Island Climate Update, No. 103, April 2009
Page 4
Tropical Pacific rainfall – March 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
March 2009
rainfall
total (mm)
March 2009
percent of
average
Australia
Cairns Airport
149
33
Townsville Airport
18
8
Brisbane Airport
47
34
Sydney Airport
61
47
Cook Islands
Penrhyn
169
55
Aitutaki
59
30
Rarotonga Airport
268
158
Fiji
Rotuma Island
206
56
Udu Point
150
47
Nadi Airport
321
94
Nausori
450
118
French Polynesia
Hiva Hoa, Atuona
175
194
Bora Bora
247
179
Tahiti – Faa’a
125
179
Tuamotu, Takaroa
73
140
Gambier, Rikitea
53
169
Tubuai
212
168
Rapa
337
269
Kiribati
Tarawa
134
67
Kanton
27
25
New Zealand
Kaitaia
46
61
Whangarei Airport
117
92
Auckland Airport
35
43
New Caledonia
Ile Art, Belep
52
22
Koumac
397
263
Ouloup
665
333
Ouanaham
447
187
Poindimie
891
223
La Roche
361
153
La Tontouta
234
176
Noumea
255
171
Moue
337
153
Territory and
station station
name
March 2009
rainfall
total (mm)
March 2009
percent of
average
Niue
Hanan Airport
380
182
Liku
251
110
North Tasman
Lord Howe Island
114
92
Norfolk Island
60
55
Raoul Island
96
59
Samoa
Faleolo Airport
N/A
N/A
Apia
219
42
Nafanua
326
89
Afiamalu
460
87
Maota
261
90
Solomon Islands
Taro
429
132
Munda
281
76
Auki
477
123
Honiara
439
126
Henderson
436
177
Kira Kira
435
119
Santa Cruz, Lata
480
107
Tonga
Niuafo’ou
267
88
Mata’aho Airport
167
56
Lupepau’u
249
83
Salote Airport
52
23
Nuku’alofa
N/A
N/A
Fua’amotu Airport
77
41
Tuvalu
Nanumea
143
42
Nui Island
276
77
Funafuti
165
44
Nuilakita
84
23
Vanuatu
Sola
455
111
Pekoa
168
49
Lamap
136
49
Port Vila
N/A
N/A
Tanna/Whitegrass
380
N/A
Aneityum
422
125
The Island Climate Update, No. 103, April 2009
Page 5
Rainfall outlook map for April to June 2009
Tropical rainfall and SST outlook: April to June 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 the March–May 2009 forecast period, a region
of suppressed convection is likely in the southwest
Pacific encompassing Tokelau, Tuvalu, and the Northern
Cook Islands, with below average rainfall expected for those
areas. Near to below average rainfall is expected for Eastern
Kiribati and the Tuamotu Archipelago.
Enhanced convection is likely in the area around Papua New
Guinea and Vanuatu, Fiji, Niue, and the Southern Cook Is-
lands, with above average rainfall anticipated for the com-
ing three month period. New Caledonia, the Austral Islands
and Tonga are expected to receive near or above average
rainfall. No clear precipitation guidance is offered for the
Pitcairn, Samoa, Western Kiribati, Marquesas, the Society
Islands, the Solomon Islands & Wallis and Futuna
The prominent SST anomalies in the region that existed
during the past few months are easing. Near or above average
sea surface temperatures are forecast for eastern Papua New
Guinea extending into the southwest Pacific, encompassing
Vanuatu, Fiji, and New Caledonia, Wallis and Futuna,
Tonga, Samoa, Niue, the Southern Cook Islands, the Society
Islands, the Austral Islands, and Pitcairn Island. Near normal
SSTs are forecast for the Marquesas and the Solomon Islands
Average or below average SSTs are expected for Eastern
Kiribati, Tuvalu, Western Kiribati, Tokelau, the Northern
Cook Islands, and the Tuamotu Archipelago.
The confidence in the forecast model 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 April is 55%, 6% lower than the
long-term average for all months combined. The SST forecast
confidence is moderate–to–high for this period.
Island Group
Rainfall Outlook
Outlook confidence
Cook Islands (Southern)
20:35:45 (Above)
Moderate-High
Fiji
20:35:45 (Above)
Moderate-High
Niue
20:35:45 (Above)
Moderate-High
Papua New Guinea
20:35:45 (Above)
Moderate-High
Vanuatu
20:35:45 (Above)
Moderate-High
New Caledonia
25:35:40 (Near or Above)
Moderate-High
Tonga
25:35:40 (Near or Above)
Moderate-High
Austral Islands
25:40:35 (Near or Above)
High
Pitcairn Island
30:35:35 (Climatology)
Moderate
Samoa
30:35:35 (Climatology)
Moderate
Solomon Islands
30:35:35 (Climatology)
Moderate
Kiribati (Western)
35:35:30 (Climatology)
Moderate
Marquesas
35:35:30 (Climatology)
Moderate
Society Islands
35:35:30 (Climatology)
Moderate
Wallis & Futuna
35:35:30 (Climatology)
Moderate
Kiribati (Eastern)
40:35:25 (Near or Below)
Moderate-High
Tuamotu Islands
40:35:25 (Near or Below)
Moderate-High
Cook Islands (Northern)
45:35:20 (Below)
Moderate-High
Tokelau
45:35:20 (Below)
Moderate-High
Tuvalu
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 April to June 2009
Island Group
SST Outlook
Outlook confidence
Austral Islands
25:35:40 (Near or above)
Moderate
Cook Islands (Southern)
25:35:40 (Near or above)
Moderate
Fiji
25:35:40 (Near or above)
Moderate-High
New Caledonia
25:35:40 (Near or above)
Moderate-High
Niue
25:35:40 (Near or above)
Moderate-High
Papua New Guinea
25:35:40 (Near or above)
Moderate-High
Society Islands
25:35:40 (Near or above)
Moderate-High
Tonga
25:35:40 (Near or above)
Moderate-High
Vanuatu
25:35:40 (Near or above)
Moderate-High
Wallis & Futuna
25:35:40 (Near or above)
Moderate-High
Pitcairn Island
25:40:35 (Near or above)
Moderate
Samoa
25:40:35 (Near or above)
Moderate
Marquesas
30:40:30 (Near Normal)
Moderate-High
Solomon Islands
30:40:30 (Near Normal)
Moderate
Cook Islands (Northern)
35:40:25 (Near or Below)
Moderate-High
Tokelau
35:40:25 (Near or Below)
Moderate-High
Tuamotu Islands
35:40:25 (Near or Below)
Moderate
Tuvalu
35:40:25 (Near or Below)
Moderate-High
Kiribati (Eastern)
40:35:25 (Near or Below)
Moderate
Kiribati (Western)
40:35:25 (Near or 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
Below
Near or
Below
Near
Normal
Near or
Above
Above
NO
FORECAST
The Island Climate Update, No. 103, April 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
Jim Salinger Email:
j.salinger@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