Number 106, July 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
June’s climate
•
The South Pacific Convergence Zone (SPCZ) was positioned
southwest of normal, and contracted toward Papua New Guinea.
•
Suppressed convection north of the Equator and near the Solomon
Islands.
•
Mostly well above normal rainfall for many parts of Fiji.
El Niño/Southern Oscillation (ENSO), seasonal
rainfall, and sea surface temperature forecasts
•
ENSO neutral conditions exist in the tropical Pacific. Many
dynamical climate models project a transition to El Niño by early in
Austral spring.
•
Below normal rainfall is forecast for Tokelau, the Marquesas and the
Northern Cook Islands.
•
Normal or above normal rainfall is expected for Papua New
Guinea, the Solomon Islands, Western Kiribati, 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. 106, July 2009
Page 2
Climate developments in June 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 June 2009 position of the South Pacific Convergence Zone (SPCZ)
was displaced southwest of its normal position, less extensive, and 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.
Soil moisture in June 2009
Estimated soil moisture conditions at the end of June 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), Raratonga
(Southern Cook Islands) and Fua’amotu (Tonga) project moist
soil moisture conditions.
T
he South Pacific Convergence Zone (SPCZ) was displaced
slightly southwest of its normal position last month, but
was contracted toward the Equator. The SPCZ exhibited less
coherent rainfall in the northeast portion of the Southwest
Pacific than in previous months. A region of enhanced rainfall
was observed over part of Fiji and the Austral Islands during
June. Suppressed convection existed northeast of Western
Kiribati last month. The regional circulation in June was
characterised by more frequent low pressure over Australia
and south of the Austral Islands, and higher than normal
pressure in the northwestern portion of the Tasman Sea to
the north of New Zealand.
Near normal to above normal rainfall occurred in Papua
New Guinea and New Caledonia in June. High rainfall was
also recorded in Samoa, the Southern Cook Islands, and the
southern fringe of French Polynesia. Stations in those areas
all received more than 120% of normal rainfall for the month.
Niue also received high precipitation, with more than 190%
of normal rainfall recorded at Liku and Hanan. Very high
rainfall fell at Niulakita in Tuvalu (see table below), which
was a contrast to near or below normal rainfall for three other
stations that reported for June. In Kiribati, Tarawa received
well above normal rainfall (230mm; 143% of normal ) for
the month. In Fiji, 80% of sites had average to above average
rainfall, and three sites had greater than 200% of normal
rainfall.
Drier than normal conditions occurred over much of northeast
Australia, parts of Vanuatu, and much of the Solomon Islands
during June. Low rainfall totals in the Solomon Islands
occurred at Honiara and Henderson, which received 21%
and 63% of normal rainfall, respectively. There were dry
conditions in the Marquesas for the month of June, with
about 75% of normal rainfall recorded in Gambier. Near
normal rainfall was recorded for the Society Islands and the
Tuamotu Archipelago.
Warmer than normal conditions occurred as a whole across
French Polynesia, with +0.4°C to +1.6°C above normal
temperatures. Increased frequency of easterly wind were
recorded in the Marquesas and the northern part of the
Tuamotu Archipelego. Across the Southwest Pacific in Fiji,
air temperatures were average to below average, with some
nights dipping below 15°C due to strong southerly flow.
Wet
Moderate
Dry
Wet
Moderate
Dry
Wet
Moderate
Dry
Wet
Moderate
Dry
June 2009
June 2008
Island Group
Location
Rainfall
(mm)
% of
avg
Comments
Solomon Islands Honiara
20
21
Record low
Tuvalu
Nuilakita
552
286
Highest monthly
total in the region
Papua New
Guinea
Daru
220
234
High
Niue
Hanan
200
222
Very high
Australia
Cairns
4
8
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. 106, July 2009
Page 3
Mean sea surface temperatures (ºC) for June 2009
Sea surface temperature anomalies (ºC) for June 2009
Forecast validation: April to June 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 June, the equatorial Pacific Ocean exhibited
ENSO–neutral characteristics. Sea surface
temperatures (SSTs) in that region have been rising
steadily since February, and are now almost +1°C
warmer than normal across the equatorial Pacific.
NINO3 and NINO 4 SST anomalies are +0.5°C and
+1.0°C, respectively, for June (and +0.6°C and +0.3°C,
respectively, for AMJ). Sea surface height anomalies
along the Equator were mostly positive and the large
anomalies in recent months west of the Dateline in
the Southern Hemisphere show signs of weakening.
Positive equatorial sub–surface ocean temperatures
in the uppermost 100m near South America, which
strengthened in May, continued to intensify with
a +4°C anomaly appearing by the end of June. The
upper ocean heat content (averaged over the top 300m)
is positive across the equatorial Pacific and intensified a
little from last month.
Westerly anomalies persisted in the trade winds west of
the Dateline during June, and peaked for a time in the
middle of the month. The TRMM ENSO precipitation
index weakened (–1.0 in May) and was around –0.65
at the end of June. ENSO–neutral conditions in the
atmosphere continued in June with an SOI value of –0.4
(+0.0 for AMJ). Tropical Pacific convection (gauged
from OLR diagnostics) was suppressed over Indonesia,
but was enhanced over southern Papua New Guinea
and the adjacent equatorial Pacific. Convection is still
suppressed along the equator east of the Dateline, and a
weakly identifiable SPCZ lies between New Caledonia
and Samoa in the western South Pacific. MJO activity
weakened in June. The MJO is expected to remain weak
during early July with suppressed convection likely to
continue over Indonesia and the Maritime continent.
The global climate model ensemble assessed by
NIWA show statistical models signaling ENSO–neutral
conditions continuing through to March 2010. However,
seven out of the 10 dynamical models suggest the recent
warming trends seen in NINO3.4 will continue. Four
out of seven dynamical models indicate a transition
into moderate El Niño by the end of the JAS season.
The ENSO discussion from NCEP suggests El Niño
conditions are likely in the next two to three months
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 April – June 2009. Near to below
average rainfall was expected for Eastern Kiribati and the
Tuamotu Archipelago. Enhanced convection was expected in
the area around Papua New Guinea and Vanuatu, Fiji, Niue,
and the Southern Cook Islands, with above average rainfall
anticipated. New Caledonia, the Austral Islands and Tonga
were expected to receive near or above average rainfall.
No clear precipitation guidance was offered for the Pitcairn,
Samoa, Western Kiribati, Marquesas, the Society Islands, the
Solomon Islands & Wallis and Futuna
The April – June 2009 forecast validation was calculated for
11 island groups (one country did not report rainfall values;
seven were forecast as climatology and were unscorable).
The global island group ‘hit’ rate was 72%, 17% higher than
average, and 11% higher than the average for all months
combined. Rainfall was overprojected for Papua New
Guinea, the Southern Cook Islands, and Vanuatu, while it
was underprojected for Tuvalu.
given the current state of favourable oceanic conditions for El
Niño development. The IRI summary estimates the probability
of El Niño in the JAS season at 62%, and a 37% chance of a
continuation of ENSO–neutral conditions. A WMO advisory
suggests the likelihood of an El Niño event in the second half of
2009 is more than 50%.
The Island Climate Update, No. 106, July 2009
Page 4
Tropical Pacific rainfall – June 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
June 2009
rainfall
total (mm)
June 2009
percent of
average
Australia
Cairns Airport
4
8
Townsville Airport
0
0
Brisbane Airport
88
124
Sydney Airport
130
103
Cook Islands
Penrhyn
N/A
N/A
Aitutaki
144
155
Rarotonga Airport
205
183
Fiji
Rotuma Island
350
152
Udu Point
85
73
Nadi Airport
113
173
Nausori
152
101
French Polynesia
Hiva Hoa, Atuona
134
78
Bora Bora
84
91
Tahiti – Faa’a
66
103
Tuamotu, Takaroa
83
92
Gambier, Rikitea
126
78
Tubuai
156
134
Rapa
257
128
Kiribati
Tarawa
230
143
Kanton
53
54
New Zealand
Kaitaia
196
132
Whangarei Airport
127
77
Auckland Airport
89
77
New Caledonia
Ile Art, Belep
153
128
Koumac
60
86
Ouloup
106
80
Ouanaham
229
151
Poindimie
266
135
La Roche
150
98
La Tontouta
95
114
Noumea
118
102
Moue
228
171
Territory and
station station
name
June 2009
rainfall
total (mm)
June 2009
percent of
average
Niue
Hanan Airport
200
222
Liku
156
193
North Tasman
Lord Howe Island
119
65
Norfolk Island
112
73
Raoul Island
148
87
Samoa
Faleolo Airport
184
198
Apia
170
128
Nafanua
188
N/A
Afiamalu
345
N/A
Maota
N/A
N/A
Solomon Islands
Taro
N/A
N/A
Munda
189
83
Auki
133
77
Honiara
20
21
Henderson
37
63
Kira Kira
223
93
Santa Cruz, Lata
235
95
Tonga
Niuafo’ou
92
84
Mata’aho Airport
17
13
Lupepau’u
95
75
Salote Airport
149
186
Nuku’alofa
60
63
Fua’amotu Airport
73
72
Tuvalu
Nanumea
154
77
Nui Island
130
65
Funafuti
194
90
Nuilakita
552
286
Vanuatu
Sola
262
91
Pekoa
343
221
Lamap
107
82
Port Vila
94
55
Tanna/Whitegrass
103
71
Aneityum
263
173
The Island Climate Update, No. 106, July 2009
Page 5
Rainfall outlook map for July to September 2009
Tropical rainfall and SST outlook: July to September 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 July – September 2009, a region of suppressed
convection is likely in the southwest Pacific
encompassing Tokelau, the Marquesas, and the Northern
Cook Islands. Below average rainfall is expected for those
areas. Near to below average rainfall is expected for Tuvalu,
Samoa, Wallis & Futuna, the Society Islands and the Tuamotu
Archipelago. Near normal rainfall is forecast for Niue.
Enhanced convection is likely along the Equator extending
from Western to Eastern Kiribati, and in the area around
Papua New Guinea and the Solomon Islands, as well as 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,
Tonga, New Caledonia, and Pitcairn Island.
The global models have shown significant shifts to near-
neutral SST conditions for most of the Southwest Pacific
region during the remainder of Austral winter. However, a
projected increase in the near equatorial Pacific sea surface
temperatures is observed in the northwest corner of the
Southwest Pacific in most models. For July – September 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 and the Solomon
Islands, Western Kiribati, the Northern Cook Islands, and
the Austral 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 July is 64%, 3% higher
than the long-term average for all months combined. The
SST forecast confidence is mostly high for this period.
Island Group
Rainfall Outlook
Outlook confidence
Kiribati (Western)
20:35:45 (Above)
Moderate
Austral Islands
25:35:40 (Near or Above)
Moderate
Cook Islands (Southern)
25:35:40 (Near or Above)
Moderate-High
Kiribati (Eastern)
25:35:40 (Near or Above)
Moderate-High
Papua New Guinea
25:35:40 (Near or Above)
Moderate-High
Solomon Islands
25:35:40 (Near or Above)
Moderate
Fiji
30:35:35 (Climatology)
Moderate
Pitcairn Island
30:35:35 (Climatology)
Moderate
Vanuatu
30:35:35 (Climatology)
Moderate
New Caledonia
35:35:30 (Climatology)
Moderate
Tonga
35:35:30 (Climatology)
Moderate
Niue
30:40:30 (Near normal)
High
Tuamotu Islands
40:35:25 (Near or Below)
Moderate-High
Samoa
40:35:25 (Near or Below)
Moderate
Society Islands
40:35:25 (Near or Below)
Moderate
Tuvalu
40:35:25 (Near or Below)
Moderate-High
Wallis & Futuna
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 July to September 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. 106, July 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