April 2007

No. 8
Contents
El Niño Outlook (April - October 2007)

1

JMA’s Seasonal Numerical Ensemble Prediction for 2007 Summer

2

Warm Season Outlook for 2007 Summer in Japan

3

Summary of Asian Winter Monsoon 2006/2007

4

Launch of New TCC Website

5

International Workshop on the Applications of Advanced Climate Information in
the Asia-Pacific Region

5

Report on the Status of Heat Islands in the Kinki Region for the Summer of 2006

7

Stratospheric Major Warming Event from February to March 2007

8

El Niño Outlook (April - October 2007)
The NINO.3 SST is likely to be below normal
from spring to summer and the negative SST
anomalies are likely to persist or strengthen fromsummer to autumn. It is likely that the ocean andatmosphere in the equatorial Pacific will become a
La Niña condition within one or two months.
In March 2007, SST averaged over the
NINO.3 region was -0.5˚C deviated from thelatest 30-year sliding mean and five-month running mean NINO.3 SST deviation was +0.5˚C inJanuary 2007. SSTs were below normal in theeastern part of the equatorial Pacific and above
normal in the western part in March (Figure 1).
Subsurface negative temperature anomalies wereprominent from the central to eastern parts in
March (Figure 2). Convective activities aroundthe date line were below normal. In the central
part, winds at the upper troposphere were close tonormal, while easterly wind anomalies were
found at the lower troposphere.
The above oceanic and atmospheric conditions indicate a La Niña event. The negative SST
anomalies from the central to eastern equatorial
Pacific are considered to persist or strengthen in
the months ahead.
JMA's El Niño forecast model predicts that
the NINO.3 SST will be below normal fromspring to summer, and around 1˚C below normal
from summer to autumn (Figure 3).
Considering all the above, the NINO.3 SST is
likely to be below normal from spring to summer
and negative SST anomalies are likely to persist
or strengthen from summer to autumn. It is likelythat the ocean and atmosphere in the equatorial
Pacific will become a La Niña condition within
one or two months.
(Ikuo Yoshikawa, Climate Prediction Division )Tokyo Climate Center

Figure 1 Monthly mean SST anomalies in the Pacific and Indian
Oceans for March 2007
Contour interval is 0.5˚C. Base period for normal is 1971-2000.

Figure 2 Depth-longitude cross sections of temperature (upper) and anomalies (lower) along the equator in the Pacific Ocean for March 2007
Base period for normal is 1987-2006.

Figure 3 Outlook of the SST deviation for NINO.3 by the El Niño forecast
modelThis figure indicates a time series of monthly SST deviations for NINO.3 (5°N-5°
S, 150°W-90°W). Thick line with closed circles shows observed SST deviations
and boxes show predictions by the El Niño forecast model for the next six months.
Each box denotes the range of SST deviation with the probability of 70%.

1

No.8 | April 2007

JMA’s Seasonal Numerical Ensemble Prediction for 2007 Summer
In 2007 summer, slightly inactive Asian monsoon is predicted,
except for the western North Pacific region, by JMA’s seasonal numerical ensemble prediction system. It should be noted that the results should be interpreted with caution due to insufficient skills for
Asian monsoon prediction.
1. Introduction
This report introduces JMA’s seasonal numerical ensemble
prediction for 2007 summer (JJA), which was used as a prognostic
tool for JMA’s operational warm season outlook issued on 25
April 2007, predicted with an initial date of 17 April 2007. The
prediction consists of 31 ensemble members and employs the twotier method: first, global SSTs are predicted using a combinationof persisted anomalies, climatology and prediction with JMA’s El
Niño prediction model (atmosphere-ocean coupled model;
CGCM), and then the specific SSTs are fed into the atmosphericmodel (AGCM). Details on the prediction system and verification
maps based on 21-year hindcast experiments are available at http://
ds.data.jma.go.jp/tcc/tcc/products/model/index.html. In the report,
predicted global SST anomalies are presented in section 2. Then,the predicted circulation fields in the tropics and sub-tropics associated with these SST anomalies are described in section 3. Finally, the predicted circulation fields in the middle and high latitudes in the Northern Hemisphere are explained in section 4.
2. SST anomalies (Figure 4)
During 2007 summer, SSTs in the equatorial Pacific are predicted to be slightly above normal in the western part and negative
anomalies exceeding -0.5°C in the central and eastern parts. Thisanomaly pattern is similar to the one typically observed during La
Niña events. In the Indian Ocean, SSTs are predicted slightly
above normal, except for the Bay of Bengal, where relatively
negative anomalies are seen. Positive SST anomalies are predictedin the Atlantic.
3. Circulation fields in the tropics and sub-tropics (Figure 5)
As expected from the predicted SST anomalies, below normal
precipitation is predicted in the equatorial central and eastern Pacific and the Bay of Bengal, while above normal precipitation ispredicted in the Maritime continent and the Atlantic. Above normal precipitation is also seen in the west coast of Mexico, which isrelated with the positive SST anomalies there. The negative SST
anomalies in the eastern part of the Pacific may further boost thepositive SST anomalies. Predicted precipitation amount is slightly
below normal in the Asian monsoon region on the whole, butslightly above normal amount is predicted for the western North
Pacific.
Upper tropospheric velocity potential anomalies are negative(more divergent) over the Maritime Continent and the Atlantic,
which is consistent with the precipitation pattern. Positive (moreconvergent) anomalies are predicted over the tropical central andeastern Pacific and the Bay of Bengal, but those anomalies overthe Bay of Bengal are small.
Corresponding to the positive anomalies of velocity potential
over the eastern Pacific, characteristic anomalies of stream function are predicted over North America in the sub-tropics, such as
positive (negative) anomalies at the upper (lower) troposphere.
Negative anomalies of velocity potential are predicted over the
Maritime Continent, but the anomalies of stream function are relatively small.

Tokyo Climate Center

2

Figure 4 Predicted SST anomalies for 2007 JJA

(a)

(b)

(c)

(d)

Figure 5 Predicted atmospheric fields for 2007 JJA(Ensemble mean of 31 members)(a) Precipitation (contour) and anomaly (shading). Contour
interval is 2 mm/day,(b) Velocity potential at 200 hPa (contour) and anomaly(shading). Contour interval is 2×106 m2/s,(c) Stream function at 200 hPa (contour) and anomaly(shading). Contour interval is 16×106 m2/s,(d) Stream function at 850 hPa (contour) and anomaly(shading). Contour interval is 5×106 m2/s.

No.8 | April 2007

4. Circulation fields in the middle and high latitudes in
the Northern Hemisphere (Figures 6 and 7)
The ensemble prediction indicates that seasonal mean
500-hPa height anomalies for 2007 summer is above normal over most parts of the Northern Hemisphere, except
for high latitudes such as the northern Atlantic and thenorthwestern part of North America. This large scale
positive anomaly might be explained by the leading modesof low frequency atmospheric variability in the Northern
Hemisphere, i.e. EOF1 and EOF2 of 500-hPa heightanomalies in JJA. The EOF1 (EOF2) scores derived fromdifferent members are statistically biased negatively(positively), which means positive anomalies would bedominant in the middle latitudes in the Northern Hemisphere.
(Akihiko Shimpo, Climate Prediction Division)(a)Figure 6 Predicted 500hPa height in the Northern Hemispherefor 2007 JJA (Ensemble mean of 31 members)
Contour interval is 60 m. Anomalies are shaded.

(c)

(b)

(d)

Figure 7 Histogram of predicted (2007 JJA) (a) EOF1 and (b) EOF2 scores defined by the (c) first and (d) second EOFs of
500hPa height anomalies in the Northern Hemisphere

Warm Season Outlook for 2007 Summer in JapanFor 2007 summer in Japan, mean temperatures are likely
to be normal or above normal in most regions. Precipitation
amounts are likely to be normal in most regions except thenorthern part where they are more likely to be above normal.

JMA’s El Niño forecast model predicts that a La Niña
condition is expected to start in this spring and last during
summer. According to a statistical investigation, a hot summer is likely in eastern and western Japan during a La Niña
event.
JMA’s seasonal forecast model predicts that convective
activities will be slightly suppressed around the Bay of Bengal. It means that the Asian monsoon activity, which is positively related to summer temperatures mainly in northernpart, will be a little weaker than normal. In this regard, itshould be noted that the forecast model has an insufficient
prediction skill over the Indian Ocean with the lead time ofseveral months. The forecast model also predicts enhanced
convective activities in the Philippine Sea. It means that thesubtropical high, which brings a hot summer to Japan, is
expected to be normal or above normal in strength. The
prediction skill for the Western equatorial Pacific is superior
to the one for the Indian Ocean.
In regard to the extra-tropical circulation, 500 hPa heightanomalies and 850 hPa temperature anomalies are predicted
to be positive in most of the Far East. Therefore, the statistical guidance based on the seasonal prediction model outputs
shows a larger probability of above normal temperatures inJapan. However, it should be aware that the predicted SLP
anomaly suggests Okhotsk highs appearing temporarily,
which often bring a cool summer mainly in northern Japan.
In addition, an attention should also be paid to the present
progress of the Asian summer monsoon because cool andwet summers were experienced following the latest three El
Niño events.
(Shunji Takahashi, Climate Prediction Division)

1. Outline of the outlook
JMA issued an outlook for the coming summer overJapan in February and updated it in March and once again
in April. It expects a hot summer with a larger probability(50% or 40%) than the climatological one (33%) in mostparts of Japan, and a wet or normal summer with a large
probability (80%) in the northern part.
A subtropical high is expected to cover Japan to an extent normal or above normal during this summer. The activity of the bai-u front is expected to be normal, but thefront is likely to stagnate in the northern part.
Probabilistic forecasts of mean temperatures and precipitation amounts for the whole summer, as well as precipitation amounts in the rainy (bai-u) season for different
regions of Japan are available at the following URL.
Summer Outlook in Japan:
http://ds.data.jma.go.jp/tcc/tcc/products/japan/outlooks/
outlook3w.html
2. Backgrounds for the outlook
Warming trends are obvious in summer temperatures inJapan, consistent with the warming trend of troposphericthickness temperatures in the northern mid-latitudes. Actually, the main islands of Japan experienced seven hot summers in the recent ten years. The oceanic condition in theequatorial Pacific has changed drastically in March froman El Niño-like condition to a La Niña-like condition.

Tokyo Climate Center3

No.8 | April 2007

Summary of Asian Winter Monsoon 2006/2007
monthly precipitation is 299.8 mm) and more than 200 mm
in the northern Sumatra Island (Figure 8).
In relation to the eastward propagation of the MaddenJulian Oscillation (MJO) in the tropics, convective activities
were above normal over the area from the Indian Ocean to
Southeast Asia from mid-December 2006. At the same time,enhanced anti-cyclonic circulation over southern Chinabrought cold northeastern monsoon winds from the middle
latitude to Southeast Asia (Figure 9).
It is considered that the active convection due to MJO
and the cold surge from the Chinese continent relates to theheavy rains in the southern Malay Peninsula and the northern Sumatra Island.

1. Extreme Climate Events
Heavy rains in Southeast Asia (December 2006 – January
2007)
It was drier than normal until November 2006 in Southeast Asia, but it became rainy in December and heavy rains
occurred in the southern Malay Peninsula and northern Sumatra Island from around 17 December. More than 200 fatalities by floods and landslides were reported in northern
Sumatra and about one million of people affected by floods
in southern Malaysia.
SYNOP data in the affected countries show that ten-day
precipitations for the period from 17 to 26 December weremore than 600 mm at Changi Airport in Singapore (normal

Figure 8 Ten-day total precipitation amounts aroundthe Malay Peninsula
Numbers in the figure denote total precipitations derived
from SYNOP reports on 17-26 December 2006.

Figure 9 Weekly mean of OLR, its anomaly and 850
hPa wind (20-26 December 2006)
OLR data are derived from the observations by NOAA's
polar orbital satellite. Solid contours show OLR (contour
interval: 20 W/m2), shadings show OLR anomalies andarrows show 850 hPa winds. Blue (red) shadings denoteareas of stronger (weaker) than normal convective activity. Base period for normal is 1979-2004.

Enhanced convection due to
MJO and northeast monsoon

2. Atmospheric circulation
The center of the Aleutian Low shifted eastward fromits normal position and the Siberian High was weak fromits center to eastern Siberia (Figure 10). This indicatesthat the northeastern Asian winter monsoon was weak andthe cold surges occurred less frequently. Three-monthly
mean temperatures at 850 hPa (Figure 11) were significantly above normal over eastern Asia. In particular, temperature anomalies normalized by the standard deviations
exceeded 2.0 from the south of Lake Baikal to northeastern China. As to the features of the upper level tropospheric circulation, which brought an extremely warm
winter to northeastern Asia, the seasonal mean polar jet
was remarkably clear and stronger than normal from

Tokyo Climate Center

Europe to Lake Baikal, which is unclear in the climatological condition (Figures 12a and 12b). This condition wasoften seen throughout the season. The jet from northern
America to the Atlantic was also stronger than normal. On
the other hand, the sub-tropical jet was weaker than normal
over the south of Japan, where the maximum wind speed
existed in the climatological condition. These features indicate that the polar jet and the subtropical jet were clearly
separated from each other over Eurasia. More details areavailable at the TCC website: http://ds.data.jma.go.jp/tcc/
tcc/products/clisys/topics/topics_200703_1.pdf(1: Hidehiko Isobe, and 2: Yayoi Harada,
Climate Prediction Division)4

No.8 | April 2007

Figure 10 (left) Winter 2006/07 mean sea levelpressure and anomaly in the northern hemisphere
Contours show sea level pressure at intervals of 4 hPa.
Shadings show SLP anomalies. Base period for normal is 1979-2004.
Figure 11 (right) Winter 2006/07 mean 850 hPa
temperature and anomaly in the northern hemisphere
Contours show temperatures at intervals of 4˚C.
Shadings show temperature anomalies. Base period
for normal is 1979-2004.

Figure 12 Winter 2006/07 mean 300 hPa
wind vectors in the northern hemisphere(a) Normal, (b) Winter 2006/2007
Black lines show wind speeds at intervalsof 20 m/s. Blue shadings show values
greater than 40 m/s. Green lines show normal wind speeds at intervals of 40 m/s.
Base period for normal is 1979-2004

(b)

(a)

Launch of New TCC Website
The Tokyo Climate Center (TCC) of JMA launched a
new TCC website on 27 March 2007 (URL: http://
ds.data.jma.go.jp/tcc/tcc/index.html). Please change yourbookmarks to the new URL.
The previous TCC websites http://cpd2.kishou.go.jp/tcc/
and http://okdk.kishou.go.jp/ will remain available until
July 2007.
TCC will continue to make efforts in order to extend
and enhance the lineup of TCC products to meet the needs
and requirements of NMHSs in the region.

For example, TCC plans to provide a probabilistic extended-range forecast of precipitation and temperature formajor observation stations in Southeast Asia through thewebsite this year. Your comments on TCC products aremost welcome. Please contact tcc@climar.kishou.go.jp.
(Kumi Hayashi, Climate Prediction Division)

International Workshop on the Applications of Advanced Climate
Information in the Asia-Pacific Region
The Tokyo Climate Center (TCC) held an “International
Workshop on the Applications of Advanced Climate Information in the Asia-Pacific Region” at the JMA Headquarters in Tokyo, Japan from 20 to 22 February 2007, under
the auspices of the Ocean Policy Research Foundation. All
the abstracts and presentation materials are available at:
http://ds.data.jma.go.jp/gmd/tcc/tcc/library/OPRF_WS2007.html

On the first day of the Workshop, “Open seminar on theapplications of climate information in various socioeconomic sectors” was held with the attendance of four invited lecturers. About 150 participants in total, including 65
from users’ sectors, joined the seminar. On the second andthird days of the Workshop (21 and 22 February), the“Workshop on the application of advanced climate information in the Asia-Pacific region” was held with 14 presentations.

Tokyo Climate Center

5

No.8 | April 2007

Through the presentations and discussions, all the participants in the Workshop came to share the following recognition required to enhance the socio-economic value of climate
information in the Asia-Pacific region.
(1) Communication with potential users of climate information is essential. Climate information should be
developed in a user-oriented manner. In order for theusers of climate information to understand the uncertainty/reliability/utility of climate predictions and forthe providers of it to understand the real needs for climate prediction, climate outlook forum/workshop involving users’ community on a regular basis could be
effective.
(2) We need to realize the decision-making processes andwhich parts of them are affected by climate variability
and change. Intermediary companies/institutions and/or social scientists are expected to significantly contribute to relevant researches.
(3) NMHSs should provide users with relevant indices,such as Heating/Cooling Degree Days, number of precipitation days and temperature-humidity combined
index, and evaluate the prediction skill of each element.
(4) Southeast Asian countries have increasing societal
needs for the advanced climate information, including
prediction and its application. NMHSs in these countries are in need of regional climate prediction products
and/or technology transfer by the RCCs in RA-II.
(5) The JRA-25 dataset is the first re-analysis dataset in
Asia and is suitable for the researches in variability of
Asian monsoon activity, tropical cyclones and MeiyuChangma-Baiu frontal system. It is expected and recommended to conduct researches using the JRA-25
data in each country.
(6) It has been indicated that the MME method is usefulfor effective use of climate prediction model outputs
produced by the Global Prediction Centers (GPCs),
including CMA, KMA and JMA. It is necessary to
promote international cooperation for applying the
MME method to operational seasonal forecasting.
(7) International exchange of data, especially meteorological and hydrological observation data which are provided only to domestic users, is quite important to develop and verify downscaling techniques and their applications.

Tokyo Climate Center

BCC of CMA and TCC of JMA introduced their activities and future plans as the RCCs in Asia to promote international cooperation in the development of prediction products
suitable for application use and capacity building. The requirements of Southeast Asian countries to the RCCs are
summarized as follows:(a) For advanced application of climate information, afaster- and larger-capacity communication network
should be established.
(b) Since the climate in RA-II is quite different from a
sub-region to another, it is desirable to hold a Climate
Outlook Forum in each of the sub-regions, such as
South Asia, Southeast Asia and East Asia. Some
ASEAN countries, such as Malaysia and Indonesia,
are the members of RA-V, so that cross-regional collaboration between RA-II and RA-V should be considered.
(c) Climate change is one of the common issues to tackle
in the region. The role of the RCCs in this mattershould be stressed and clarified. Regional climatechange scenarios provided by RCCs would be useful.
(d) It was shown that there exist some predictable signals
in the forecast with a lead-time ranging from a week tofour weeks, although the predictability differs between
sub-regions. It is useful that the RCCs develop some
application products derived from forecasts targeting
within one month ahead, and provide monitoring results of the current situation.
(e) It is useful that the RCCs continually provide webbased and easy-operating application tools for the useof NMHSs.
(f) Technology transfer from the RCCs to NMHSs
through training courses and workshops, particularly
the ones regarding new techniques in climate applications, is required.
(Shingo Yamada,Fukuoka District Meteorological Observatory)

6

No.8 | April 2007

Report on the Status of Heat Islands in the Kinki Region for the Summer of
2006
The Japan Meteorological Agency (JMA) analyzed heatisland effects on the climate of the Kinki region for thesummer of 2006. JMA issued a report (in Japanese) on thisanalysis.
In August 2006, this region received a longer sunshinewith a lot of sunny days and the monthly mean temperatures exceeded normal in many places. Figure 14 shows atime series of monthly mean temperatures of August in
Osaka, in comparison with Tokyo, in which a statisticallysignificant increasing trend of 1.17°C per 50 years was analyzed. This trend is larger than the corresponding value ofTokyo, 0.83°C, and two or three times larger than that inareas not affected by urbanization.
JMA made an analysis through a numerical experimentby taking 12 cases in which a Pacific subtropical high pressure covered the region and a breeze blew from the sea.
Findings from this experiment are as follows:(1)such areas extended to the basins of Kyoto and Nara,with a core exceeding 35°C from the east of Osaka to
Kyoto (Figure 15b).
(2)
A numerical simulation to quantify the effects of urbanization indicated that areas with such effects werelimited to coastal areas at 5 a.m. (Figure 16a) while
such areas extended to the whole plain at 3 p.m.
(Figure 16b). When simulated for calm and clear
days, such differences within a day are typically analyzed, as previously shown in the case of areas aroundTokyo. The area affected by urbanization was smaller
in Osaka than in Tokyo, because of smaller urban areas near Osaka.
(3) It was also simulated that a cooler breeze blowing from
Osaka Bay in the late afternoon was heated to be forced
up by urban land cover and artificial heat emissions,which avoided the cooler air flow from proceeding toinland areas, including the northeast of Osaka, Kyoto
and Lake Biwa (Figures 16b and 17).

On average, an area of high temperature above 25°C
covered areas from the coast of Osaka Bay to thenortheast of Osaka at 5 a.m. (Figure 15a). At 3 p.m.,(Hiroshi Nirasawa, Climate Prediction Division)

Figure 14 Time series of monthly mean temperature for August in Tokyo and Osaka.
Red and blue lines indicate 11-year running mean and long-term linear trend from 1934 to 2006, respectively.

(b)

(a)

Figure 15 Distribution of surface temperature and wind in the Kinki region at 5 a.m (a) and 3 p.m. (b), averaged over 12 cases for calm and clear days

Tokyo Climate Center

7

No.8 | April 2007

(a)

(b)

Figure 16 Simulated distribution of urban effects at 5 a.m. (a) and 3 p.m. (b), expressed as temperature and wind withurban effects averaged over the 12 cases deviated from simulation without such effects. Warm colors indicate positive
urban effects.

Figure 17 Vertical cross section of simulated effects of urbanization, expressed as temperature and wind with urban effects deviated from simulation without such effects in the case of 3 p.m., 5
August 2006. Warm colors indicate positive urban effects.

Stratospheric Major Warming Event from February to March 2007
Two stratospheric sudden warming events took place from February to
March 2007. One of the events was identified as “Major Warming”.
The Climate Prediction Division of JMA routinely monitors the stratospheric circulation, focusing on Stratospheric Sudden Warming (SSW)
events. STRAT-ALERT reports are issued everyday during the occurrence of SSW.
In 2006/2007 winter, two SSW events occurred. These events which
occurred from 3 to 9 February 2007 and from 22 February to 3 March
2007 were classified as “Minor Warming” and “Major Warming”, respectively.
When the latter occurred, the polar vortex shifted to the eastern side of
the hemisphere. Temperatures were distributed in a meridionally reversed
manner in the zonal mean field and easterly winds were observed over thepolar region. These conditions continued until the beginning of March.
Temperature at 30 hPa was almost below normal except for the periods ofthe two warming events (Figure 18). The major warming event was not
remarkable in comparison with the event which occurred in 2005/2006
winter. More details on the events in 2006/2007 winter are available at theTCCwebsite:http://ds.data.jma.go.jp/tcc/tcc/products/clisys/topics/
topics_200703_2.pdf.
(Hiroshi Hasegawa, Climate Prediction Division)

Figure 18 Time series of temperature at 30hPa
over the North Pole in 2006/2007 winterBlack line shows 2006/2007 winter. Gray line shows
normal.

Any comments or inquiries on this newsletter and/or the
TCC website would be much appreciated. Please e-mailto the following address:
tcc@climar.kishou.go.jp(Chief Editor: Kumi Hayashi)Tokyo Climate Center (TCC), Climate Prediction Division, JMA
Address: 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan
TCC website: http://ds.data.jma.go.jp/tcc/tcc/index.html

Tokyo Climate Center8

No.8 | April 2007