Monsoon system study inGAME-T Project
Dr. Jun Matsumoto(Department of Earth & PlanetaryScience, University of Tokyo)

Current Status of the GAME• GAME Phase-I (FY1997-2001; IOP=1998) was successfullyfinished.
• GAME Phase-II research phase (FY2002-2004) has started!
• The 1st GAME-II International Science Panel (GISP) was
held at NASDA/EORC, Tokyo in October 6-7, 2002.
• Further data archive (meteorological data for 1997-2002)
effort among the GAME-related countries was agreed.
• The international workshop for Regional Climate Modelingfor the (Asian) monsoon system was held at FORSGC,Yokohama in March 2003.
• Continuous observation and monitoring effort is being madethrough CEOP-Asian Monsoon Project (CAMP) (including
FORSGC, CREST-Water Cycle Projects.)

Objectives of GAME- Phase II(Research Phase 2003-2004)••••

Intensive & Extensive Data Analysis using
GAME data sets.
Comprehensive modeling of Asian monsoon
climate and hydrological cycles.
Application of GAME outputs for theprediction of hydrological cycle (precipitation,runoff etc.) in monsoon Asia
Further international cooperation formeteorological & hydrological studies in Asia

GAME-II Working Groups•••••••••••

Land surface processes/ABL/AAN (Joon Kim, M.Sugita)
Radiation processes (T. Nakajima)
Cloud/Precipitation processes (H.Uyeda)
Monsoon system study (J.C.L. Chan, J. Matsumoto)Monsoon system modeling (F.Kimura)Re-analysis (N. Yamazaki)
Satellite utilization (K.Nakamura, T. Koike)
GAIN (K.Takahashi)
GAME-Siberia (Georgiadi, T. Ohata)
WEBS (B.J. Sohn, K. Masuda)
WRAP (T.Oki, Thada)

Plan for Monsoon System Study in GAME-II
By Dr. Jun Matsumoto & Prof. Johnny C. L. Chan; GISP-II, Nov. 7, 2002

Main target: Pre-monsoon and monsoon onset
processes
How:• Organize workshop (national) February 5-6, 2003 in
Kyoto• Organize international workshop (in the week ofNovember 10, 2003) with GAME-T2 Workshop in
Thailand co-organized with SCSMEX Project Office• Include satellite and re-analysis related studies• Organize regional studies/collaborations with
Indochina countries• Write review paper on pre-monsoon and monsoon
onset Processes

Forested area is decreasing during
1960 to 2000
50%

10%
1960

2000
(Kanae et al., 2001: J. Hydromet., 2, 51-70)

Deforestation in
Thailand isremarkably seenfrom Vegetation
Index (NDVI)Forest exists

What is its impact
on climate?

Decrease trend in Rainfall in September

Numerical Simulation
with a regional climate model
Regional Climate Model
based on CSU-RAMS•basic equations:non-hydrostatic•precipitation:
Arakawa-Schubert
Bulk cloud microphysics•radiation:
2-stream, k-distribution•surface flux:
bulk method

-T

Rainfall trends in Thailand (1951-1994)

ÅObserved trendsÆSimulated changewith deforestation
condition by RAMS

Both Obs. andSimulated change
show remarkble
decrease of rainfall inSeptember.
Kanae et al.(2001),J. of Hydromet.

September:- the month of rainfall peak
- the month of monsoon wind disappearance

The 2nd International Workshop
of Regional Climate Modelingfor the monsoon systems• Co-sponsors: GAME-ISP and FRSGC• Topics:monsoon climate, energy and hydrological processes inmonsoon regions, orographic effects on precipitation, etc.
• Place: IGCR (JAMSTEC) in Yokohama, Japan• Date: March 4-6, 2003
• Participants: about 30 to 40 scientists and modelers• For further information;– Fkimura@atm.geo.tsukuba.ac.jp, Yoshikane@jamstec.go.jp• The 3rd Workshop will be held in April 2004 in Hawaii

Discussion: Regional climate models applied to the study of theMonsoon systems
Session 1 - Chair: Johnny C.L. Chan – March 7, 2003

Progress:• Only a few studies on simulation/prediction (hindcasts) have been done
• Predictions of the time averaged large-scale flow are generally not too much of aproblem• Most of the errors are associated with smaller-scale features such as waves, troughs,precipitation (distribution, amount, phase).
• Potential Problems:• Diurnal variations• Cloud (shallow vs. deep convection) and radiation - WCWang• Land-surface processes and forcing - Kimura• Orographic effect - Kimura• Domain size and resolution – Yliu, Ywang, Kimura,JChan• Data for initial conditions and validation (satellite) – Ywang, KYang• Interaction between ocean and atmosphere• Sub grid scale processes• Future directions: - in the next 5 years• Experiments with different schemes/numerics• Interaction between different timescales for simulation/prediction - WCWang• Sensitivity experiments to study physical processes associated with the monsoonsystem (winter and summer)*CRCP*• Simulation of individual episodes• Study of water cycle in Asian Monsoon area - RLeung• Contribution of high resolution models to regional climate simulations

Heavy Rainfall
Distribution in Thailand:
A Preliminary Study
Hiroaki Takahara
andJun Matsumoto(Department of Earth & Planetary
Science, University of Tokyo)

Introduction• Heavy rainfalls are very important
climatological events sometimes causing
flood disasters.
• The purpose of this study is to clarify
climatological (spatial, seasonal, and interannual) characteristics of heavy rainfalls
over Southeast Asia.
• This is a preliminary study in Thailandfrom 1998 to 2000.

Data & method• Precipitation data – daily precipitation data
at 106 TMD stations including agromet.
stations, for 3 years from 1998 to 2000.
• Daily surface weather charts and upper
wind fields at 600 meters analyzed by
TMD are used to classify synoptic systems
as the cause of heavy rainfalls.

Data & method (contd.)• For each heavy rainfall (>=50mm/day), thecause is identified in 6 synoptic systems,
TC (tropical cyclone; typhoon), ITCZ (ITCZ;intertropical convergence zone), LC (localcyclone), WM (westerly monsoon), EM(easterly monsoon), and Ot (others).

Identification of causes• TC: Tropical cyclone (Typhoon). The cases in whichheavy rainfall occur in the closed isobar of typhoon,
including local cyclone changed from tropical cyclone.
• ITCZ: ITCZ (Intertropical convergence zone). Thecases in which heavy rainfall occur in and near theITCZ and connected cyclones.
• LC: Local cyclone. The cases in which heavy rainfall
occur in the closed isobar of local cyclone.
• WM: Westerly monsoon. The cases in which heavyrainfall occur under westerly wind from the Bay ofBengal.
• EM: Easterly monsoon. The cases in which heavy
rainfall occur under easterly wind from the South
China Sea.
• Ot: Others. For example, the cases of southerly or
northerly wind.

Causes of heavy rainfalls• By classification,WM, ITCZ, andEM are the maincauses of heavy
rainfalls inThailand.

Min. Average

CauseMax.

TC

400.57

ITCZ

1504.44LC

300.62

WM

7307.91

EM3604.40

Ot

600.83

Seasonal Change of heavy rainfalls• 29 stations are selected to be almost 2stations per 1 degree of latitude, and used
to study about seasonal characteristics.
• Scatter diagrams of heavy rainfall eventsin 1998, 1999, 2000, and composite of 3years are made with vertical axis as
latitude and horizontal axis as day number(1-365).

050

100

day number
150
200

250

300

20N El Nino

350
La Nina20N(a)1998
10N

10N

20N La Nina

La Nina20N(b)1999
10N

10N

20N La Nina

La Nina20N(c)2000
10N

10N

20N (d)1998-2000

20N

13N
10N

13N
10N
JFM

AM

JJ
monthATC

ITCZLCWMEMOtSON

D

Scatter diagram of heavy rainfall events in (a) 1998,(b) 1999, (c) 2000, and (d) composite of 3 years.

100150300

WM(90%)(H) (I)

TC(12%)

LC(15%)

LC-dominant season

TC(10%) WM(12%)

Rare heavy rainfal season

Seasonal division based on dominant causes (over 10%) of heavy rainfalls in Thailand.

EM(27%) ITCZ(31%) WM(31%) EM(19%)

ITCZ(53%) EM(62%) ITCZ(54%)ITCZ(62%)(EM is second dominant)

ITCZ-dominant season(WM is second dominant)(I)

WM(40%) WM(17%) EM(26%) WM(36%) WM(22%)

EM-dominant season(F) (G) (H)EM(60%) LC(67%) ITCZ(48%)ITCZ(64%)ITCZ(75%)

ITCZ-dominant season(A) (B) (C) (D) (E)

WM-dominant season

J F M A M J J A S O N D (month)

EM(87%)

EM(74%) 10N

20N

350 (day number)(E) (F) (G) heavy(onlraiy n1fal )

250

10N

ITCZ(10%)

WM(71%)

200

13N(only 3 heavy rainfal s) (A)(B) (C) (D)

50

13N

20N

0

Concluding remarks• Main causes of heavy rainfalls in Thailand
are ITCZ, WM, and EM.
• Orographic effect is clear in case of WM
and EM, but it is not clear in ITCZ.
• In northern division, ITCZ-dominantseason is the longest in total. In southerndivision, WM-dominant season and EMdominant season are almost 5 months ormore.

Future works• Longer data (30 years or more?)• Data in other Indochina countries (Vietnam,Laos, Cambodia, and Myanmar)• Inter-annual variability of heavy rainfalls,including their relation to El Nino/La Nina
event

Inter-annual Variation of
Tropical Cyclone approaching
Indochina
Hideaki SHOJI
andJun MATSUMOTO(Department of Earth and PlanetaryScience, University of Tokyo, JAPAN)

Introduction• This investigation shows the seasonal andinter-annual variations of the TCs approaching
Indochina (TCIC).
• Also shown are the characteristics of the largescale flow pattern between the abundant TCIC(ATCAC) and no TCIC (NTCIC) years in orderto through insight on the mechanism of interannual variations of the number of TCIC.

Data and Method• Tropical cyclone best-track positions for 50
years from 1951 to 2000 are obtained from theJapan Meteorological Agency (JMA). Some ofTCs generated over the WNP move westward
across 110°E and approaching Vietnam coast.
These TCs are called TCIC in the present paper.
• To investigate the large-scale flow patterns, themonthly mean wind data at 850 and 500 hPa areutilized based on the reanalysis of the National
Center for Environmental Prediction (NCEP) forthe period 1951-2000. The wind data at 500 and850 hPa are utilizedFigs.1 to 3. Inter-annual and seasonal variations of TCs

Fig. 4-1. Tracks of TCs with maximum wind speed above 17.2m/s for
the ATCIC-years(left) and NTCIC-years(right) for the months of Jun-Jul.
“Star” is the point at which the maximum wind speed of TCs becomes
above 17.2m/s for the first time.

Fig. 4-2. As in Fig. 4-1 but for the months of Aug.-Sept.

Fig. 4-3. As in Fig. 4-1 but for the months of Oct.-Nov.

Fig. 5-1. Monthly wind vectors (left) and anomalous wind vectors(right) at 500hPa for the ATCIC-years for the months of Jun.-Jul.

Fig. 6-1. As in Fig. 5-1 but for at 850hPa.

Fig.5-2. Monthly wind vectors (left) and anomalous wind vectors(right) at 500hPa for the ATCIC-years for the months of Aug.-Sept.

Fig.6-2. As in Fig. 5-2 but for at 850hPa.

Fig. 5-3. Monthly wind vectors (left) and anomalous wind vectors(right) at 500hPa for the ATCIC-years for the months of Oct.-Nov.

Fig.6-3. As in Fig. 5-3 but for at 850hPa.

Fig.7. The large-scale flow patterns for the ATCIC-years• The number of TCIC in a year has no long-term trend.
TCICN in JJ and ON has increasing trend for theperiod 1951-2000, but TCIC in AS has decreasing
trend.
• The inter-annual variation of the number of TCIC is not
related to that of TCWNP.
• When abundant TCs approach Indochina, theanomalous easterly from east of the Philippines to theIndochina Peninsula is found at 500hPa.
• The variation of TCIC is related to the easterly windalong the south edge of Pacific High in Jun-Aug.
• Between July and August, the effect of monsoon flow
over Indochina to the TCIC is reversed.
• In Oct-Nov, the westerly monsoon across the Malay
Peninsula and the northeasterly monsoon are bothstronger in ATCIN-year.