AMEGEWEX Asian Monsoon Experiment

GAME Letter
Activity Review of GAME-T
GAME-T Review Group
1. Introduction
Among GAME research components, GAMETropics (GAME-T) bears a role to observe and investigate the energy and water cycle in the humid
temperate region of the Asia Monsoon region, fromthe tropics to the sub-tropics, especially in the Indochina
peninsula. The main target area for hydrological studies is the Chao Phraya river basin in Thailand. Other
areas or larger regions (e.g. whole Indochina) can be
the target for various research purposes. The areas
are characterized by the small seasonal change oftemperature and the predominant diurnal cycle oftemperature and precipitation. The magnitude of seasonal evolution of surface soil wetness is quite large
where dry season is observed, and interannual variability of precipitation is as predominant as diurnal
cycle. The release of latent heat in the atmosphere isconsiderably large as the heat source of the global
atmospheric circulation, and drives the Asian Monsoon system.
On the other hand, population density in this regionis generally high, and the crop production supporting
the large population is directly influenced by water
resources. Therefore the prediction of precipitation
and runoff is not only challenging scientifically but also
contributing to societal issues through improving theaccuracy of water resources prediction.
The goal of GAME-T is to accomplish its role wellconsidering these characteristics of the target area as
one of key sub-programs of GAME.
The objective of GAME-T is quantitative monitoring of vapor flux, precipitation, evapotranspiration,
radiative flux and their seasonal, intra-seasonal andinterannual variation at the target area of Southeast
Asia. In paticular,

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1) difference of water and energy fluxes at land surface among several representative land cover types,
such as paddy field, grassland, forest and so on,2) surface wetness which differs significantly in thedry and wet season, and
3) diurnal cycle of precipitation and other hydro-meteorological variables,
have been focused on.
The better understanding of the role of such waterand energy cycles in the Asian Monsoon climate system and improving the accuracy of seasonal hydrometeorological prediction are vital issues of the research in GAME-T, as well.
In order to accomplish these objectives, various
field observations,and data collections have beenplanned and implemented. The year of 1998 was set
to be the Intensive Observation Period (IOP) of
GAME and organized field observations and data collections were carried out.
The IOP of GAME-T is mainly divided into two
periods. Phase I - Monsoon onset: middle of April to
middle of June.Phase II - Mature stage of monsoon:
middle of August to middle of September.
The observation in the transitional season from thewet to the dry season is also of interest and was implemented.
The schedule of each observation during IOP issummarized in Figure 1, and the locations of theseobserving stations are illustrated in Fig. 2. Subsequent
or intermittent observations has been continuously
carried out up to now, although major IOP activities
were done during these two periods. The data wasprocessed or under processing partly, and all the data
will be available at:
http://hydro.iis.u-tokyo.ac.jp/GAME-T/GAIN-T
where GAIN stands for GAME Archive Information
Netowrk, and GAIN-T is one of the distributed archive
center of GAIN responsible for GAME-T related

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datasets. Detailed description on the individual dataset
should be found either in associated document withthe data on the Web or in scientific papers publishedby the principle investigators of each observation.
The research components of GAME-T can be divided into 5 sub-groups:
1) Land surface flux observation and modeling,2) Investigation of diurnal cycle of precipitation using
radar and numerical modeling,3) Rawinsonde observation and analysis, and the description of climate in GAME-T,
4) Hydrometeorological database for GAME-T(GAIN-T),
5) Hydrological modeling, regional atmospheric modeling and their coupling.
The summary of each sub component is shown in thefollowing sections. The remained problems and thefuture perspective of GAME-T are described in thelast section.

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GAME Letter No. 3

Fig. 2. The locations of the observing stations

2. Land surface flux observation and modeling
2-1. Land surface flux observation
The land surface flux observations by GAME-T
members have been conducted mainly at three pointsof monsoon forest (Kog-Ma), paddy field (Sukhothai)and shrubbery forest with grassland (EGAT site inTak) partly since 1996 and mainly since 1998. These
three stations are located in the Chao Phraya river
basin. They are also included in the GAME-AAN
observation network. These activities aim to offer
basic datasets for the construction and the improvement of one-dimensional land surface model to estimate energy and water flux from typical land surFig. 1. The schedule of each observation during IOP

faces of Southeast Asia. At the observation sites, net
radiation and basic hydro-meteorological parameters
have been continuously observed, and time series ofenergy and water fluxes have been estimated.
The statistics of land use classification in the northern region and the central plain of Thailand show thata half of the upper Chao Phraya river basin is covered by forests, 30 % is ‘unclassified’ and a half ofAME

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cultivated area, namely 15% of total, is paddy field.
The landscapes of the three flux observation sites correspond to these major land uses. However, Kog-Ma
experimental site is located at higher altitude compared to whole forest region in the Chao Phraya river
basin, and it may not represent the energy and water
flux of forest region in the area. The shrubbery forestand mixed land-used site (EGAT) was set up assuming that most ‘unclassified’ area could correspond tosuch a landscape. The paddy field site (Sukhothai) is
located in a typical non-irrigated (rain-fed) paddy fieldregion. In addition to these flux observation sites, operationally observed hydro-meteorological data in
Thailand is managed by TMD (Thai Meteorological
Department), RID (Royal Irrigation Department), andRFD (Royal Forestry Department). These operational
data can be used for flux estimation (e.g. Hirota, 2001).
All the data including the observations at flux sites
and the operational data are stored in the GAIN-T
web page for the easy access from the entire world.
Some basic datasets will be stored in a GAME cdrom
which will be published in the fall of 2001.
Some new findings were obtained through theanalysis of the land surface flux observations. The
seasonal variations of heat fluxes were determinedusing the data during the Intensive Observation Period (1998) and the following seasons. For example,
Figure 3 represents the seasonal patterns of heat budget observed at the EGAT site. The flux measurements at this site were substantially started on May in1998 (DOY150). It is clearly found that dominant heat
flux component was changed from sensible heat (H)to latent heat flux (LE) at around 180 in DOY of 1998
(the end of June), and then it was changed from latent heat to sensible heat at the end of 1998. This
striking contrast in dominant heat component arosewith the seasonal pattern of precipitation. In the dry
season (from November to March or April), low soil
moisture content and low vegetative activities caused
low evapotranspiration from the terrestrial surface.
Sensible heat flux consumed about 60% of total avail-able energy (Rn-G). During the mature stage of therainy season, latent heat flux used 50 to 80 % of total
available energy. April to June is the transitional season. The dry-rainy seasonality was also clearly foundin the observed data of the paddy field. This contrasting seasonality of heat budget can be said as a typicalcharacteristic in the plain area of the Southeast Asianmonsoon region. However, a different situation was
found at the upland forest site (Kog-Ma). In the forest site, transpiration in the dry season is higher thanin the wet season. It is mainly due to abundant solar
radiation and atmospheric humidity deficit in the dry
season. The shortage of soil moisture in the dry season does not have much effect on transpiration at thisforest site. Soil moisture in the deep layer might beutilized for transpiration. Although such larger transpiration in the dry season was observed in an Amazonian experiment as well, we should investigate carefully whether this situation occurs just at this place oris possible over the whole forested region. Interannual
variability should also be investigated.
These observed and estimated fluxes can be utilized for improving the land surface models, partly
described below, in the next step of the GAME activities.
References:
Hirota,T., 2001: Estimation of seasonal and annual evaporation using agrometeorological data from the Thai
Meteorological Department by the heat budget models, J. Meteor. Soc. Japan, 79 (1B), 365-371
Toda,M., N.Ohte, M.Tani and K.Musiake: Observation of
evergy flux and evapotranspiration over terrestrial
complex land in the tropical monsoon region, J. Meteor. Soc. Japan, submitted

2-2. Land surface modeling
These datasets obtained through the observations
above are useful for calibrating, validating and developing land surface models, which can be used fordescribing hydrological and meteorological phenomena on terrestrial surface in general circulation models. The simple biosphere model 2 (SiB2) by Sellers

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et al. (1996) was adopted for the simulation of waterand energy cycles at paddy field using the observed
data at the paddy field site (Sukhothai) as inputs. This
land cover type, paddy field, has the over-surface
water of which heat capacity is comparatively large.
Water budget and radiation flux of paddy field could
be different from those of normal cropland owing to
the water surface. Then, the SiB2 was revised into
SiB2-paddy incorporating water surface over the land,and validated (Fig. 4).
The result of the original SiB2 simulation showsthat net radiation (Rn) agrees with the observation.
However, simulated latent heat flux (lE) had an early
peak, and carbon assimilation rate (A), sensible heat
flux (H), soil heat flux (G), surface soil temperature(Tg) and canopy temperature (Tc) are a little bit unrealistic. The SiB2-Paddy simulation improved the diurnal cycle of these parameters if compared with theobservation. In terms of total energy and water budget for several days, Rn, lE, and A are not much different between the SiB2 and the SiB2-Paddy simulation. It is partly because H and G are too small compared to net radiation and lE, and the mean biases are
not significant. It can be said that SiB2-Paddy is preferable for the realistic simulation of the diurnal cycleof lE and surface temperature, which, in turn, may
affect the diurnal evolution of convective activity inthe atmosphere.
These numerical simulations were carried out on a
web-based interactive software system, named as“SiB2 on WWW.” It was developed as a part of aPh. D research on computer science. This system
can be used through the internet. It has a graphycal
user-interface which can consider the user’s preferences, and it is based on massive database technology. Everyone can use it at
http://www.tkl.iis.u-tokyo.ac.jp:8080/DV/sib2/ .
Due to the delay of database construction and observed data processing, application of the land surface model to the forest and the shrubbery land is not
carried out yet. It can be realized in the very near

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future.
References:
Kim,W., T.Arai, S.Kanae, T.Oki, and K.Musiake, 2001: Application of the Simple Biosphere Model (SiB2) to apaddy field for a period of growing season in GAMETropics, J. Meteor. Soc. Jpn., 79 (1B), 387-400

2-3. Rainfall observation in a mountainous area
For the accurate estimation of hydrological budget
in a basin, the altitudinal increase in precipitation
amount has a significant meaning. In order to determine the characteristics of altitudinal dependence inrainfall in mountainous area of the GAME-T hydrological targe area, 13 rain gauges were installed in a
mountainouswatershed of3853 km 2 since 1998. The
number of gauges has increased since then. Afterinvestigating carefully, it was found that the altitudinalincrease in rainfall was obvious in the two wet seasons in 1998 and 1999. It means that the rainfall
amount increases as the elevation gets higher. The
altitudinal increase was also found in the dry season,
however, the increment was smaller in the dry season. It was also found that not the rainfal intensity
but the rain-falling hours can cause the altitudinal increase. More detailed analysis has being carried out(Kuraji et al., 2001). This altitudinal increase in rainfall and the observed evapotranspiration describedabove will be used for the real estimation of water
budget of the target area.
References:
Kuraji,K., P.Kowit and M.Suzuki, 2001: Altitudinal increasein rainfall in the Mae Chaem watershed, Thailand, J.
Meteor. Soc. Japan, 79 (1B), 353-363

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Oct. 2001

Observed Energy Budget at the EGAT site

Dry

Rainy

Rainy

Dry

[EGAT: mixed land use]

Fig. 3. Seasonal pattern of energy budget observedat the EGAT site

800
Rn-ObslE-SiB
H-SiB
G-SiB
lE-Obs
H-Obs
G-Obs
W-Obs

-2

Energy Flux (W m )

A

600
400
200
0

-200
0

6

12

Time (h)1824Fig. 4. Simulation of the diurnal evolution of surface energy components by the original SiB2
(upper) and the revised SiB2 with paddy scheme(lower). The simulated results are comparedwith observations.

3. Investigation of diurnal cycle of precipitation
using radar and numerical modeling
The convective cloud systems in the tropics releasehuge amount of latent heat into the tropospheric atmosphere and play an important role in driving global
circulation of whole atmosphere. The amount, location and time of precipitation are important factors insimulating the climate of the Earth. General circulation models (GCMs), however, fail to simulate maxima
of diurnal variation of precipitation over the land; theanalyses using Tbb revealed late afternoon or night

maxima of precipitation over tropical land areas
whereas GCMs produced early afternoon maxima.
This difference of timing of the maximum precipitation between GCM simulations and observations certainly has climatic effects through the difference ofradiational properties of clouds between day and night.
Radar observations and rain gage observations give
more direct information on precipitation than Tbb observation from space. In GAME-Tropics, therefore,
intensive radar observations and collection of rain gage
data were done from 1998 to 2000. In 1998, radar
data at 5 radar sites were archived. In 1999 and 2000,
radar observation was done only at Chiang Mai. Routine observation data were archived once per hourand 24 hours over one day. Additional GAME-T radar observation, whose range is about half of operational one but has more sweeps in a volume scan,
was performed only in daytime at Chiang Mai andPhitsanulok, and 24 hours at Khon Kaen and Phuket
in 1998. In 1999 and 2000, GAME-T radar observation was performed once to twice per hour in 24 hours
over one day. Because radar data at Chiang Mai had
good quality and were collected several years, we analyzed those data most intensively. The results are as
follows:
1) Echo area showed significant diurnal variation
throughout the observation period. Averaged echoarea at 3 km height reached its maximum at 15-16
LT at Chiang Mai. At Khon Kaen, and the maximum time was several hours later than that at
Chiang Mai.
2) In most of observed days, each echo moved eastward at Chiang Mai. Line shaped echoes were also
found in about half of these days (Fig. 5).
3) Monthly averaged echo data showed that an areaof high echo probability appeared in late afternoon
in south of Chiang Mai and shifted eastward withtime. The same tendency was also noticed at Khon
Kaen.
4) Inter-seasonal variation and inter-annual variation
were evident. Precipitation mechanisms in August

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possibly differ from the mechanisms in earlier months
in the same monsoon season.
In the extensive analysis of observed rainfall data
(Ohsawa et al. 2001), evening to night maxima werealso observed by rain gages . Rain gage data also
showed that precipitation maxima later than the midnight were locally observed: the most northeastern partand the southeastern part of Thailand where the monsoon wind impinges mountain ranges nearly in a rightangle.
Numerical simulation is a powerful tool to analyze
and determine important factors for meteorologicalphenomena in detail. A set of numerical simulation
targeting precipitation over Thailand was completed.
Using a non-hydrostatic two-dimensional cloud ensemble numerical model initialized by June climate
conditions, diurnal variation of precipitation was simulated successfully. The simulated results (e.g. Fig. 6)
indicated a new mechanism producing diurnal variation of precipitation in Indo-China Peninsula (Satomura
2000):a) Convective clouds were triggered at the lee-side
foot of mountains in the late afternoon. They areorganized to squall lines.
b) Those squall lines propagate eastward and producenight maxima of precipitation over the inland areas
far eastward from the mountain.
c) The timing and location of convection initiation aredetermined by the solar-synchronized intrusion ofcold air from the windward side into the lee sideand by the mountain wave.
The results 2) and 3) of radar data analysis agreewith results (a) and (b) of numerical simulation. High
resolution Tbb analysis also confirms the eastward
shifts of cloud activity with time over Thailand. The
connection between this section and the next section
should be investigated in the next stage.
References:

Ohsawa,T., H.Ueda, T.Hayashi, A.Watanabe andSatomura, T., 2000: Diurnal variation of precipitation over

mm/h. Dash-dotted line indicates moving speed of 7

the Indo-China Peninsula: Two dimensional numeri-m/s. The surface topography is depicted by the black

cal simulation, J. Meteor. Soc. Jpn., 78, 461-475

shading at the bottom of the figure.

J.Matsumoto, 2001: Diurnal variations of convective
activity and rainfall in tropical Asia, J. Meteor. Soc.
Japan, 79 (1B), 333-352

Fig. 5. Ratio of days when eastward-moving echoes
and line-shaped echoes were observed to totaldays of observation in each month at Chiang Mai(upper) and Khon Kaen (lower).

Fig. 6. Horizontal-time section diagram of precipitation
rate averaged on the second and the third days. Contours of precipitation are 0.5, 1 and 10 mm/h. Shaded
area indicates precipitation rate is greater than 1

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4. Rawinsonde observation and analysis, and climatological description
The heating and radiative effects due to convective clouds play an important role in the generationand maintainance of large-scale monsoon circulations.
In order to understand the generation mechanism of
diurnal, intraseasonal and seasonal variations of convective activity, as partly menioned in the previous
section, it is important to clarify the background atmospheric conditions. Thus, the enhanced rawinsonde
observations were conducted for 6 times during 1996
and 2000. The observed data are used for the atmospheric process analysis described below as well as it
was transmitted through GTS in real time and contributed to objective analyses including GAME-4DDA by
JMA. In addition to the rawinsonde observation, otheratmospheric observations such as MPL (MicroPulse
Lidar), wind profiler, GPS and sky radiometer observations have been carried out in the GAME-T area. A
part of them will be described in the chapter of GAMERadiation.
The seasonal change of Southeast Asian monsoon
in a climatological sense was also studied by using thehistorically accumulated data by TMD (Thai Meteorological Department) and the ECMWF objetive analysis data.
4-1. Results of the enhanced rawinsonde observations
The GAME-T enhanced rawinsonde observations
were conducted at the special station (Sukhothai or
Nongkhai), and at the 3 operational TMD upper-air
stations (Bangkok, UbonRatchatani, Chiang-Mai) in
Thailand. The special stations were established andmaintained by GAME-T members.
The enhanced observations were conducted 8 times
from 1996 to 1999 in the wet season, the dry season
and the transitional season. Each enhanced observation period continued approximately for two weeks.
During each enhanced observation period, rawinsondes were launched 4 or 8 times a day at the spe-

7
cial station. The prominent characteristic of theseobservations is the high frequency (3 or 6 hour interval) balloon launch. They revealed quite clear figures of diurnal and intraseasonal variations in wind
and temperature.
Figure 7 shows a time-height section of diurnal
component of equivalent potential temperature variations in the rainy season. It is found that the atmospheric structure is more unstable in the night timethan in the day time. This fact is interesting because
the stability variation may be closely related with thenight time rainfall shown in the previous section. So,
it is an important issue to understand the physicalmechanism of the connection between the cloud activity and the atmospheric stability.
As for the diurnal variation, the opposite land-sea
breeze (i.e., wind from land to sea in the day timeand opposite wind in the night time) was observedwith the boundary layer radar at Bangkok. This phenomenon is quite peculiar and is one of the puzzles
the GAME-T researches. It is also the future subject to understand such an opposite circulation.
Figures 8 and 9 show time-height sections ofequivalent potential temperature in the pre-monsoon
period and in the mature monsoon period, respectively. Figure 8 is the composite of 1, 7, 9.3 and 14
day period component, and Fig. 9 is that of 1, 8.5,
11.3 and 17 day period component. It is found thatabout 2-week periodic variation dominates in the premonsoon period (Fig. 8). Downward phase progression with time is clearly seen in the middle and upper
troposphere (above 5 km) and no phase difference inheight is observed in the lower troposphere (below 5km). On the other hand, in the mature monsoon period (Fig. 9), quasi 2-day variation has large amplitude. The similar features were found all over the
Indochina peninsula during monsoon period.
The details are described in two publications “Enhanced rawinsonde observation in Thailand in 1996
and 1997” and “Enhanced rwainsonde observation
for GAME-Tropics IOP in 1998” both available fromAME

8GAME and GAME-T offices.
4-2. Climatological description of the Southeast
Asian monsoon
It is generally believed that typical monsoon wind
shift occurs between wintertime northeast monsoon
and summer-time southwest monsoon in Southeast
Asia including the Indochina Peninsula. This is true,of course, especially over the oceanic areas, for example, in the Bay of Bengal. In general, the wintermonsoon corresponds to dry and fine condition, while
the summer monsoon being wet and rainy situation inland areas except in east coast of the peninsula. However, it is shown by Matsumoto (1997), that the seasonal change process of wind and rainfall regime is
not always simultaneous. The rainy season in inlandpart of the Indochina Peninsula starts earlier (in late
April) than the seasonal wind shift to the summertime monsoon circulation (in mid-May) characterized
as lower westerly embedded with upper easterly flow.
Furthermore, the lower tropospheric westerly is already established in early April in northern India andIndochina regions as a part of mid-latitude westerly
wind system.
In order to show why such peculiar seasonalchanges are generated in the Indochina Peninsula,large-scale conditions of wind, temperature and height
fields at 850 hPa were analyzed using the ECMWF
operational analyses. Due probably to dynamical reason, the center of the subtropical high is located incentral (not northern) India in December. Then
warming over northern India even from February induces the heat trough to be located in northern Indiaand it gradually extends southward from December
to April. In short, warming of the lower tropospherein mid-winter over south and southeast Asia is themain reason why southerly or westerly wind establishes in the midst of winter in northern Thailand thenproceeds in central Thailand during the winter-spring
seasonal transition. Further study is needed how warming in winter-spring season is related with the onset

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process of summer monsoon circulation.
For the purpose above, a lot of operational meteorological data of several countries in southeast Asia
were collected extensively. The data are stored in
the GAIN-T database and will contribute to various
kinds of research in the future.
References:
Matsumoto, J,. 1997: Seasonal transition of summer rainyseason over Indochina and adjacent monsoon regions. Advances in Atmospheric Sciences, 14, 231245.

Fig. 7. A time-height section of diurnal component ofequivalent potential temperature variations in
the rainy season.

Fig. 8. A time-height section of equivalent potential
temperature in the pre-monsoon period (composite of 1, 7, 9.3 and 14 day period component).

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Fig. 9. A time-height section of equivalent potential
temperature in the mature monsoon period(composite of 1, 8.5, 11.3 and 17 day period component).

5. Hydrometeorological database for GAME-T:
GAIN-T
One of the main objectives of GAME-T is to collecthydrometeorological data and to construct comprehensive hydrometeorological dataset over tropicalAsia. The GAME-T database team has carried out
this mission for all period of GAME-T phase 1 andfinally established the on-line dataset on the WWW
network. The URL is:
http://hydro.iis.u-tokyo.ac.jp/GAME-T/GAIN-T/
index.html
This dataset consists of three categories of sub
datasets. First is long-term routine (operational) observation record mainly of Thailand as well as othersome southeastern Asian countries. This category hassome climatic values (rainfall, temperature, wind speed,
sunshine duration, relative humidity, etc.) and hydrological values (soil moisture, river discharge, etc.). The
duration of such data is mainly from early 1980’s up to1999 and temporal resolution is usually daily, with few
exception of 3-hourly or hourly. This first category
data were used in the hydrological simulations described in the following section.
Second categoly of dataset is that of intensive observation mainly in IOP (rainy season of 1998). Results of radiation and energy flux observation at three9
selected sites with high temporal resolution are included in this dataset, which allow us to validate landsurface schemes by real field observation. Other
datasets, such as that of rawinsonde observation
records and densely distributed rain-gauge network
will help us to understand 4-D structure of climate
system over this area and to make grid-based climatic
datasets for IOP.
Third category datasets are collection of values
from some remote sensing techniques. This includes
3-D radar rainfall, MPL (micropulse lidar), wind profiler
and satellite remote sensing.
Database management system has also been constructed, which gives future DB managers an easy
way to maintain this DB. Currently, however, the userinterface that can help scientists to manipulate andanalysis these datasets as they like has not been established adequately. This remains one of the important issues we have to make more effort.
6. Hydrological modeling, regional atmosphericmodeling and their coupling
In order to investigate and forecast water resources in the target basin, the Chao Phraya, two kindsof hydrological model were developed. One is a fully
distributed hydrological model on 10 km grid system
which consists of 3D equations for surface, subsurface and ground water movement, and a river network solution (Jha et al., 1997, 1998). Another is asemi-distributed hydrological model incorporating a 2D
hillslope submodel and a 1D river channel submodel
based on the representation of the geomorphologicalstructure of the basin (Yang et al., 2001). They wereapplied to the Nakhon Sawan catchment of the Chao
Phraya basin, the largest catchment in the basin.
The simulations were conducted with the historical hydro-meteorological data in 1990’s for several
years, resulting good agreements with the observed
discharge. Since they are a full- or semi-distributedhydrological models, the distribution of soil moisture
as well as river discharge were investigated. An irri-

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gation submodel was developed and is being incorporated into the semi-distributed model for water resources assessment.
A part of the full-distributed hydrological model
was applied to an upstream basin for flood forecasting simulation for a few hours to a few days. In the
beginning, it was just a research. However, it became of practical use. Actually, this flood forecasting
system was installed in the hydrological center No.2
of RID in Chaing Mai city so as to forecast a flood in
Chiang Mai city. To make this system more valid in
the real situation, a telemetry system for this forecasting system is desirable.
As a starting point of coupling a regional atmospheric model and hydrological model for the application to this region, a three-dimensional regional atmospheric model simulation was carried out, showing thatheavy and wide deforestation in the northeastern partof Thailand clearly reduced the amount of precipitation over the deforested area and increased the amountover the down-wind area (Kanae et al. 2001). Thiseffect is evident in September and it coincides withobservation.
However the general coupling of atmosphericmodel and hydrological model is still in the stage oftrial and error.
References:Jha, R. and Herath, S. and Musiake, K., 1997: Development

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Indochina Peninsula, J. Hydrometeorology, 2, 51-70

7. Workshops and publications
International workshops on GAME-T were heldin Thailand for 5 times, in 1996, 1998, 1999, 2000 and
2001. They were two-day workshops, and the last
one was a three-day workshop. Approximately 100
to 150 participants from Thailand, Japan and othercountries joined each workshop with enthusiastic discussion. In 2000 and 2001, the guests from neighboring nations (Vietnam, Cambodia, Malaysia andMyammar) were invited to the workshops for the future cooperative studies on hydrology and meteorlogy
between Southeast Asian nations. Post proceedingsof the workshops were published. In addition to theworkshop proceedings, two publications on rawinsonde
observation were also publised. These publications arelisted below.
List of Publication
Proc.’96 Workshop on GAME-Tropics in Thailand
Proc.’98 Workshop on GAME-Tropics in Thailand
Proc.’99 Workshop on GAME-Tropics in Thailand
Proc.2000 Workshop on GAME-Tropics in Thailand
Proc.2001 Workshop on GAME-Tropics in Thailand
Enhanced Rawinsonde Observation in Thailand in1996 and 1997
Enhanced Rwainsonde Observation for GAMETropics IOP in 1998of IIS distributed hydrological model and its application in Chao Phraya River basin, Thailand, Annual
Journal of Hydraulic Engineering, JSEC, 41, 227-232
Jha, R. and Herath, S. and Musiake, K., 1998: Application of
IIS distributed hydrological model in Nakon Sawan
catchment, Thailand, Annual Journal of Hydraulic Engineering, JSCE, 42, 145-150
Yang,D., S.Herath, T.Oki and K.Musiake, 2001: Applicationof distributed hydrological model in Asian monsoon
tropic region with a perspective of coupling with atmospheric models, J. Meteor. Soc. Japan, 79 (1B), 373385
Kanae,S., and T.Oki, and K.Musiake, 2001: Impact of Deforestation on regional precipitation over the

8. Future perspective
Two new synthetic research components havejust begun. The first one is the integrated investigation on the monsoon onset and evolution over Southeast Asia. This synthetically includes the large-scale
climatic study, the analysis of rawinsonde observation, the analysis of land surface flux observation, theland surface modeling study and the climate modelingstudy in GAME-T. Utilizing such many sub-components, we hope to clarify the interactive mechanism
between land surface and atmosphere in the stage ofthe monsoon onset and evolution over Southeast Asia.

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Another is the estimation of water and energy budget
at the land surface over the Indochina peninsula presumably on 0.1 degree grid system. This needs theinterpolation and extrapolation of hydro-meteorological variables, just like 4DDA for land surface, using
the observed data and satellite data. This also needs aland surface model which is well calibrated at eachland type by the observed land surface flux data. The
result of this study will become a primal illustration ofenergy and water budget over Indochina.

Except for the synthetic research components inthe future as described above, the general future
perspective of GAME-T is as follows.
Even though the scientific findings prevailed throughGAME/GAME-T project are magnificent, there seemsome research aspects that will not be accomplishedwithin the time period of GAME-T. Major concern isthe lacking or less application of scientific achievements for water resources management even though
the importance of understanding and predicting themonsoon variability is highly emphasized in the GAME
Science Plan published in 1994. It should be notedthat in the GAME Implementation Plan, two scientific objectives are clearly focused at the biginning:・To understand the role of Asian monsoon in the global energy and water cycle,
・To improve the simulation and seasonal predictionof Asian monsoon and regional water resources.
The first phase of GAME/GAME-T has been concentrated on building up the comprehensive observational network and data collections. Now, it should be
the time for utilizing the obtained precious dataset forscientific and social issues. Integration among various observational facts, statistical data processing, andmodeling approach should be required as partly described in the beginning of this section, and it will not
be accomplished throughly within a year until March
2002.

11
Finally, the most relevant fruit of GAME-T could
be the international research community organizedunder the project and firmly formed through the collaborative field experiments, joint data processing, andthe exchange of various ideas at frequent meetings,
workshops, and symposia. A lot of efforts will be required to build up such a smooth, constructive, andsignificant scientific community again. Therefore, eventhough current project funding of GAME-T will befinished March 2002, a follow up project should preferably inherit the research community and mechanism,and continue to promote the science and societal contribution initiated by GAME-T.

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12

Oct. 2001

GAME/HUBEX research activity
GAME/HUBEX Research Group
1. Main research topics
The energy and water cycle in the subtropical monsoon region of East Asia is characterized largely by
the Baiu/Changma/Meiyu front in summer. It extends
eastward from the eastern edge of the Tibetan Plateau and brings a huge amount of rainfall in East Asia
in early summer. Its formation and maintenance processes are largely affected by the Southeast Asiansummer monsoon (SEAM), the western North Pacific summer monsoon (WNPM), the mid-latitude
westerly systems, and so on. It is interesting that thevery humid and the dry climate regions are adjacent
to each other just around the Meiyu front in China,
affected by the Tibetan Plateau.
Various scale of cloud/ precipitation systems areformed in this frontal zone and play a major role in theenergy and water cycle in the zone. The purpose of
GAME/HUBEX is to make clear the role of mesoscale cloud systems in time variation of regional scaleenergy and water cycle, and to reveal their evolution
and response to time variation of land surface conditions.
In 1998, HUBEX group performed meteorological observation during the period from May to August. During the intensive field observation, a recordbreaking flood occurred in the Yangtze River region.
A large amount of important data was obtained by thefield observation. Following 1998, HUBEX group also
performed meteorological observation in 1999: surface flux observations and the intensive field observation of meteorology and hydrology in June and July.
Synoptic scale situation was largely different from thelast Meiyu season. The long term monitoring of flux
has been conducted since 1998.
2. Continental scale Asian monsoon variability
We analyzed the global precipitation data to study
long-term variation of seasonal change of precipita-

GAME Letter No. 3

tion during the period from June to August in East
Asia and the Western Pacific Ocean. Seasonal variations of precipitation can be classified into three patterns A, B and C (Fig. 1). The pattern A is that theintense precipitation area showed no northward shift
and its amount decreased from June to August. The
pattern B is characterized by a continuous northward
shift of intense precipitation from 5 N to 15 N withincreasing amount. The pattern C showed a shift from15 N to 25 N with large amount of precipitation inJune and August while less amount in July. These
patterns are related to water vapor flux and have strong
correlation with precipitation of Meiyu in China andBaiu in Japan.

Fig. 1. Averaged monthly precipitation amount in the patterns A, B and C from June to August.

3. Regional scale energy and water cycles
Land-atmosphere interaction and its role in theformation of mesoscale precipitation systems are oneof the most important research targets of GAMEHUBEX. We tested the JSM-SiBUC model using
GAME reanalysis data as initial and boundary conditions. Figure 2 shows simulated and observed rainfall
for the Huaihe River Basin (11 deg.× 5 deg.) from 27
to 30 June 1998. This model can predict the rainfall
area rather well, but the predicted rainfall amount islarger than the observed one (especially on 27 June).

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GAME Letter No. 3

13

Oct. 2001

Fig. 2. Simulated and observed (surface station’s data) precipitation in Huaihe River Basin (11 deg. × 5 deg.)

4. Frontal-scale characteristics of cloud systems
Frequent appearance of mesoscale convective cloudsystems results in the persistent heavy rainfall area in
the Meiyu frontal scale. It is interesting that such convective clouds are sometime associated with meso-scale
circulation and interact with that circulation systemstrongly. As for the meso-scale lows, so-called the southwest vortices appear frequently around the Meiyu front
in China, initiated around the eastern foot of the Tibetan
Plateau.
It is noted that the Meiyu frontal rainfall area became organized into a meso-scale clouds, and a mesoscale low was generated after that. Distribution of thenegative relative vorticity at 500 hPa level suggests thatpersistent generation of the instability associated withthe strong low-level southerly wind around the shear
line initiated and sustained the heavy rainfall area, resulting in the formation of the meso-low. It is interestingthat the synoptic scale low-pressure area near the surface level extended to the northwest of the Meiyu frontal zone around the Huaihe River Basin. This low-pressure area seemed to be associated with the heating fromthe ground. In relation to this low-pressure area, thelow-level southerly wind component reached to penetrate

further northward around Fuyang (32.5 N/ 116 E),
where cloudless area existed just to the north of
the Meiyu cloud zone. Due to such change in the
low-level wind field, the destabilization of stratification for deep moist convection was brought there
through the differential advection of the equivalentpotential temperature. The present study illustrates
an example that the activation of the Meiyu frontal
rainfall due to the synoptic scale system would result in the initiation of the meso-scale low.
Cloud clusters are important cloud activity of the
Meiyu front over the China continent. Precipitation
within cloud cluster over the continent is important
for the water cycle in this region. A diurnal variation of cloud activity including cloud clusters was
significant over the continent during HUBEX IOP.
Most of cloud clusters began to develop at the lateevening and attained maximum of the lowest cloudarea at midnight (Fig. 3.). This is a significant diurnal variation of cloud clusters over the continent.
We are trying to simulate the features of cloud clusters by using several mesoscale models (MRINHM, ARPS, RSM, etc.)

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Oct. 2001

Fig. 3. Time variation of area of cloud clusters
with Tbb lower than -60 C.

5. Mesoscale cloud systems
In the Doppler radar observation range, main
precipitation systems were observed from 29 June to
3 July, 1998 (Uyeda et al., 1999). It is quite interesting that the Meiyu front moving to the north (south)
showed a warm (cold) frontal-like structure as shownin Fig. 4. In addition, the front had three types of substructures, that is, warm frontal, cold frontal and mesovortex types (Maesaka and Uyeda, 1999, 2000a).
Warm frontal type of precipitation was in the morningof 29 June 1998 and cold frontal type in the afternoonof the day (Maesaka and Uyeda, 1999, 2000a) (Fig.5.).
Meso- γ scale vortices were observed in the precipitation systems on 2 July (Fig. 6.). Wind fields anddivergence profile in and beside the precipitation systems are analyzed with VAD winds by Fujiyoshi et al.
(1999, 2000). Evolution of meso-β scale precipitation systems was studied by using Fuyang radar (Xuand Xu, 1999) (Fig. 7.). Water budget in the Fuyang
radar observation range (r = 250 km) was analyzed
by using sounding data at 7 stations by Maesaka andUyeda (2000a). Structure and development processesof the precipitation system of cold frontal type are
analyzed from a different point of view (Kato et al.,GAME Letter No. 3

1999; Geng et al., 2000; Maesaka and Uyeda, 2000b).
In cold frontal type southwesterly inflow in the low
altitude and condensation in the low altitude ahead of
the precipitation area were prominent. In meso vortex type, condensation above 3 km and ahead of the
precipitation system, and evaporation behind it are
analyzed.
After the main precipitation period, diurnal variation of convective clouds is recognized under the subtropical high from 11 to 15 July, 1998 (Uyeda et al.,2000). On July 13 1998, a deeply developed and longlived cumulonimbus cloud was observed by Doppler
radars. It developed in the atmospheric situation of
weak vertical wind shear and its primary updraft was
situated in the rear portion relative to the storm motion. It seems that the presence of the broad downdraft
observed around the region of low to mid-levels northeasterly inflow contributed to the development andmaintenance of downdraft. It is interesting that, under the influence of low-level inflow from the northeast side, interaction between convective-cells occurred and long-lasting and very deeply cumulonimbus cloud was formed in the atmospheric conditionof weak vertical wind shear. On 16 July a squall line
passed over the Doppler radar sites (Tsuboki et. al.,2000). An intense convection was located along theleading edge and decaying convection behind the edge.
A parallel component of relative velocity was significant at every level of the squall line. Convective cells
successively developed on the downshear side of thisparallel component. As a result, a long line was formed.

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GAME Letter No. 3

15

Oct. 2001

Fig. 4. Time-height cross section of wind speed measured by a Doppler radar at Feng Tai. The left panel (from 29 to
30 June) showed a warm frontal structure and the right panel (from 1 to 3 July) showed a cold frontal structure.

Fig. 5. Dual-Doppler radar analysis for 1842 BST
on 29 June 1998. a) Horizontal plane at 2.0 km
in height. b) Vertical cross-sections along A-A’lines in (a). The vector denotes the wind on theplane. Vectors of (b) are subtracted from the averaged wind. The shading denotes the radarreflectivity.

Fig. 7. GANAL wind (solid arrows) and geopotential
height (contoured every 10 m) superimposed
Fuyang radar reflectivity (0.4 PPI scan) at 700hPa and 500 hPa (20 BST 29 June 1998). Opencircle shows the sounding point and open arrows
denote the wind by sounding at the level.

Fig. 6. The reflectivity (PPI, El=0.4) of Fuyang radar at 0750 BST on 2 July 1998 (top panel). Horizontal plane of dual-Doppler radar analysis at 2.5
km in height (bottom panel). The round arrow
indicates the vortex .

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16
6. Study of land-surface hydrological processes
To predict floods, droughts and future water resources for a large river basin, a macro scale distributed hydrological model is an indispensable tool. For
modeling water movement of a large river basin, modeling procedures such as basin partitioning, hydrological process modeling for a sub-basin, linking sub-basin models together to make a total runoff model require heavy tasks. Thereby, automatic proceduresfor processing hydrological modeling are necessary
so that a model is transferable to various large
catchments. In automatic modeling procedures, processing channel network linkages should also be included to incorporate a river flow routing model efficiently.
To satisfy such modeling requirements, a macroscale grid based distributed hydrological modeling system using OHyMoS, Object-oriented HydrologicalModeling System (Takasao et al.,1996, Ichikawa etal., 2000) is developed and applied to the Huaihe Riverbasin in China. In the system, a watershed basin is
subdivided into grid boxes according to a grid systemof a meso-scale atmospheric model to incorporate
atmospheric model outputs. By using the values ofmodel parameters identified at the Shigan River basin(Fig. 8), the hydrological simulations for the HuaiheRiver basin were conducted.
A basic framework for building a macro scale
distributed hydrological simulation system is as follows:i) division of a river network into several sub-networks by rectangular grid boxes set by a numericalatmospheric model,ii) modeling of hydrological processes in each gridbox (runoff element modeling),iii) modeling of channel flow routing in each grid box(flow routing element modeling),iv) building a total simulation system by connecting
subsystem models composed of the runoff element
models and the flow routing element models.
To test the simulation model for working cor-

Oct. 2001

GAME Letter No. 3

rectly, hypothetical precipitation was given to the system. This simulation shows that time lag of the peaks
between two hydrographs is about three days. It is
important to consider the effect of river flow routing.

Fig. 8. Channel network for the Huaihe River above Bengbu

7. Concluding remarks
Many studies have been done on the structure andcharacteristics of precipitation systems during the intensive observation period of the GAME/HUBEX. Although a large number of reports were made on the
structure of each precipitation system, the study ofinteraction between meso- α and meso- β scale
systems is few. Combination of Doppler radar data,
conventional weather radar data, sounding data, satellite data and surface data is expected. We should
utilize objective analysis data and proceed to 4DDA.
Only a few studies with numerical simulation are reported; for a squall line on 16 July by Tsuboki et al.
(2000) and for an isolated convective cloud on 14 Julyby Shinoda et al. (2000). We are also encouraged to
do numerical simulation for understanding the structure of precipitation systems and water circulation in
and around the systems.
For HUBEX area, moisture budget analyses with
objective analysis data as Peng and Song (1999) andmoisture sink analyses with sounding data as Lin etal. (1999) would give information on the backgroundof the precipitation systems. Doppler radar data are
fully used for analyses of three dimensional wind fields

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GAME Letter No. 3

Oct. 2001

in precipitation systems. However grid data of windvelocity available for statistical analyses are not ready.
If we have time series of updraft field it will be very
useful.
Reflectivity data of three Doppler radar need careful calibration and consideration of attenuation (Xu etal., 1999). Reflectivity data of Fuyang radar is very
useful for understanding the structure of precipitation
systems (Xu and Xu, 1999; Geng et al., 2000). Classification of precipitation types such as convective or
stratiform are tried with Fuyang radar data (Zhang etal., 1999). However Fuyang radar data had fluctuation of reflectivity and its value is compared with
TRMM precipitation radar data and disdrometer(Uyeda et al., 1999). Satellite data are very usefulfor the study of precipitation systems as follows. Estimation of precipitation amount using TRMM TMI istested by Li et al. (1999). Further studies on the principle of satellite infrared rainfall estimation and passive microwave measurement, applied to the strong
convective systems during the IOP by Zhang et al.,(1999) would be hopeful. Retrieval of water vapor
above 500 hPa by using GMS-5 WV (water vapor)channel during the IOP by Osaki et al. (1999) would
be useful for comparison with precipitation systems.
Comparison with GMS IR data and hourly surface
rainfall data, as shown by Zheng et al. (1999), is also
necessary. Analyses with objective analysis data and
GMS data as Tuboki and Monoe (2000) would be
important.
As many studies on the structure of precipitation
systems are made with Doppler radar data and Fuyang
radar, we know what kind of precipitation systems
we had during the IOP. However surface data is not
used well and further use of satellite data should be
encouraged for the study of large scale characteristics of Meiyu frontal precipitation systems at the sametime with objective analysis data. 4DDA with observational data is expected for better understanding.
Numerical experiments with synoptic model and cloud
resolving model are also important. Combination of17
all of the analyses and investigation on the multi-scale
structure and multi-processes of precipitation systems
would be the most important target of the study.
For the comparison with precipitation systems in
another areas, studies on the statistical feature of precipitation system are required; precipitation types,
averaged vertical profile of reflectivity (rainfall intensity), updraft and non-adiabatic heating, and averaged
precipitation efficiency. As basic data set for various
studies are ready and provided, further processed data
set such as grid rainfall amount and updraft distribution are expected.
It would be important for HUBEX researchers toreach to mutual understandings on a few focal points
to study in a few years and present situation of studies. At the same time we have to provide better community data as soon as possible. Submission of each
paper to scientific journals and publishing of special
issue of HUBEX would be necessary. It would be
important to continue collaboration in the study of the
GAME/HUBEX for understanding precipitation systems during the IOP and Meiyu/Changma/Baiu frontal precipitation systems from China and Korea toJapan.
Most papers cited in this report are found in thefollowing Proceedings.
Proc. of Workshop on Meso-scale Systems in Meiyu/
Baiu front and Hydrological Cycle. Xi’an, China(3-9 November, 1999) (GAME Publication No. 25)
Proc. of International Conf. on Mesoscale Convective Systems and Heavy Rain in East Asia, Seoul,
Korea (24-26 April, 2000)
Proc. of 13th International Conf. on Clouds and Precipitation, Reno, Nevada, USA, (2000)
Proc. International GAME/HUBEX Workshop,
Sapporo, Japan (12-14 September, 2000) (GAME
Publication No. 23)

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18

Oct. 2001
Report on research progress ofSiberia Regional Project

1. Background and general information
GAME (GEWEX Asian Monsoon Experiment) selected one of their field experiment sites in Siberia.
Importance of this area was, first, that it is a northern
region with widely covered snow cover/permafrost
and possess typical surface such as taiga forest andtundra which occupies a large area on Eurasia Continent. Second is that there is abundant freshwater runoff to the Arctic Ocean which may strongly affectthe ocean circulation. Thirdly, this region is one center of the recent intense warming and better understanding is needed on the response of the land surface and possible feedback to the climate system.
In order to advance the study, we set up the following objectives.
1) Clarify the physical processes of the land-surface/atmosphere interacting system.
2) Clarify the characteristics and variability of regional energy/water cycle.
3) Obtain the climate trend and land-surface change
during the past 50 years and evaluate possible feedback processes.
4) Improve and develop models describing the energy/water exchange and atmosphere-land surface
systems.
5) Collection and archive of regional ground based/satellite data.
6) Establishment of observational network for longterm study, and development of hardware.
Four main strategies for implementation were set.
The first was to select one large drainage for study,
which was Lena River, eastern most drainage among
the three large Arctic flowing rivers. Enisei and Ob
were candidates at the beginning, but they were omitted due to warmer climate and more anthropogenic
influence than Lena. Second was to establish three
local observation sites for intensive study from the

GAME Letter No. 3

criteria of land surface condition and climate in thedrainage (Tundra area facing Arctic Ocean, flat taiga
with little precipitation, mountain taiga with much precipitation). The location of these sites are shown in
Fig. 1. Third was to hold an intensive study period forinvestigating the land surface/atmosphere interaction
and spatial and temporal variability of water/energy
fluxes in a regional scale (100 km scale), which was
implemented in year 2000. The fourth is to involve
researchers of various disciplines such as biology, soil
science and others that can contribute to the understanding of the water/energy cycle in this region.
The study period was 1996-2001, and tight cooperation between Japanese and Russian institutions/scientists lead to a success. Table 1 shows the time
sequence of the research progress for the group. The
main results obtained in various study groups basedon Japanese scientists will be presented were.

Fig. 1. The map of the study region and position of
local observation sites.

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GAME Letter No. 3

19

Oct. 2001

Table 1. Yearly progress of the essential part of the Siberia Regional Project.

Year

1995

1996

GAME
Conference(Pataya)
GAME 1st Int.
Workshopon
Siberia (Nagoya)patch Tundra(tiksi)
Constructionofscale
preliminary mastPatch
in the study area
Drainage

1997

1998

1999

2000

2001

GeneralMain meetings

GAME
Conference(Cheju)2nd Int. Workshop on
Siberia (Moscow)

GEWEX/GAME
Conference (Beijing)
MAGS-GAME
Meeting (Edmonton)Localdrainagestudy

Installment of the Continued
whole obs. system
UpgradedStart of runoff meas. theobs.
and drainage study
system.

Continued

Continued

Continued

Helicopter
startedContinued

obs. Continued

Continued

Continued

Continued

Taiga Forest(Spasskaya)
Patch
Areal

Aug.:Construction Setting of the wholeof
32m
tower obs. system(larch)Setting of part of
instrument
andsoil moisture/tempmeas.

Taiga(Tynda)
Patch
Drainage
Regional
intensive
study

obs.

Variation, large
scale
analysis,
Model studies

Made on personal Made
basis
basis

on

personal

2. Tundra region
Tundra group stressed the following topics to beinvestigated.
(1) Seasonal and inter-annual variation of water balance of tundra watershed(2) Seasonal variation of 1-dimensinal energy andwater fluxes on tundra surface.
(3) Spatial distribution of surface and soil conditions
The following preliminary results have been obtained.
Figure 2 shows the map of the observation site.
The observations for the patch scale energy and water exchange (theme 2) were carried out by ACOS
(Automatic Climate Observation System) with a 10
m meteorological mast including the profiles of soil
temperature and water contents for 4 years from 1997
to 2001. The result shows that, about 24 % of the net
radiation reached at the ground during summer was
spent as sensible heat fluxes back to atmosphere, 4555 % as latent heat flux to the atmosphere, and 20-30% as conductive heat flux into the ground. (Fig. 3.).
Rather large amount of heat is used to melt the frozen

Continued

GAME Conference(Nagoya) planned
2nd MAGS-GAME
Meeting (Sapporo)plannedConstruction of 2nd Continued
24m tower (pine)
StartedNegociation
takes Constructionofnegociations time
24m tower andwith SHI
network
withinthe drainage
And start of obs.
Setting of tower, April to June:
several masts and Aircraft
meas.
AWS at 7 sites in the were made.
right bankAugust: half ofland obs. finish
Made
on Made on personal Made on personal
basis
basis
personalbasis

Continued
Intensive obs.
being madeisMade on personalbasis

ground where the melted depth is 50-100 cm at themost. Seasonal and inter-annual variations of summertime sensible and latent heat fluxes are relatively
small. The dependence of these fluxes to the winddirection is seen as being reported by Yoshimura et al.
(1999) for a coast site at Alaskan tundra. In case ofsouthwest wind from interior with hot and dry air mass,
sensible fluxes is small (sometimes changes its direction) and the latent heat fluxes large, while the northeasterly air masses is cold and damp, sensible heat
flux is relatively large and the latent heat flux small.
Concerning the water balance (theme 1) of awatershed of 5.5 km2, runoff, spatial distribution ofsnow cover and precipitation were studied. Inter-annual variation in annual precipitation was large (150400 mm). About 80-150 mm of annual precipitation
was as snow. The distribution of precipitation in thewatershed was homogeneous at least from the study
in 1998. Small vegetation height and strong wind enhance the redistribution of snow and form the snow
drift, which acts as a natural snow dam during snow-

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20

GAME Letter No. 3

1

2

Fig. 2. Map of observational site at Tiksi (tundra)
1: hydrological station, 2: meteorological station

Heat flux over Tundra -Bowen ratio method
200.0

150.0

RN
G
E
H

100.0
W/m2

melt season and becomes a source of summer discharge of the stream in the tundra watershed. The
first day of snowmelt runoff was rather constant at
the beginning of June for 4 years from 1997 to 2000.
It is different from northern Alaska, where the firstday of snowmelt runoff varies for more than one
month. Most of initial snowmelt was refrozen inside
the snow pack. The water level of a lake in the watershed changed seasonally with the ground waterlevel. The change of water storage in ground could
be estimated from the runoff curve. The evapo-transpiration was different by the vegetation, such moss,
sedges, gravel. The water balance of tundra watershed was obtained for three years. (Table 2)
Seasonal variation of water cycle was simulated
well by a one-dimensional model. The simulation ofdischarge by a nested hydrological model was improved by putting the place of snowdrift into accountin the model.
Distribution of vegetation in the watershed wasinvestigated and it was found that average LAI ofmoss was about 5. The distribution of thaw depth has
auto-correlated patterns about every 7 m, which might
be reflecting the hexagonal ground patterns. The thaw
depth at the depression in the ground where soil water was relatively deep and different from general information in the past, which might be caused by the
percolation of snowmelt water or rain．
The system of water and energy exchange anddrainage runoff in this area seems to show different
characteristics in certain aspects from the reports for
the Alaskan sites.

Oct. 2001

50.0

0.0

-50.0
11/
4
6
8
2
4
6
8
1
3
1
1
1/9 2/31 /1/9 /30/9 /29/9 /28/9 0/27 2/26 /24/0 /24/0 /23/0 /22/0
/98
/99
/99
9
9
9
0
0
8
9
0
0

Date

Fig. 3. Seasonal variation (10 days mean) of heatbalance components at Tiksi from 1998 to 2000.
Table 2. Summer water balance at Tiksi watershed.
P: Precipitation, M: Snowmelt contribution,
E: Evaporation, Q: Runoff, dS: Change in groundstorage.

Year
PeriodP
M
EQ
1997
6/18-9/4
220*1
187*2
67*3
381*1
*1
*2
*3
1998
6/18-9/4
76
120
44
148*1
1999
6/13-9/8
99*1
65*5
55*6
110*1
average
131
124
55
213
Std.Dev.
77
61
11
146
*1 Observed, *2 Degree day Method, *3 Bulk Method*4 Recession Analysis, *5 Residual, *6 Penman Method

dS
-41*4
5*4
-1*4
-13
24

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GAME Letter No. 3

Oct. 2001

21

3. Taiga forest
The predominant land surface condition in Siberia
is the taiga forest, and this strongly influences the waterand energy cycle in this region. Study was done at
Spasskaya Pad near Yakutsk.

mula varied widely and canopy resistance and evapotranspiration efficiency were strongly controlled by
the saturation deficit, and the efficiency decreased
exponentially with the increase of the saturation deficit.

3.1 Meteorological conditions during the observation period 1997-2000
The meteorological data was obtained from 1997
to 2000. The amounts of precipitation from May toAugust were 81.5 mm, 235.7 mm and 131.7 mm in
1998, 1999, 2000, respectively and shows broad fluctuation year to year. The depth of active layer is 1 to
4 m in this area, deeper than Tiksi, the tundra site.

3.3 Differences of the energy balance characteristics between the larch forest and the pine forest.
The energy budget above a pine forest was observed in a warm season in 2000. The effective radiation and the sum of turbulent fluxes were almost
balanced in this site. Figure 6 shows the time series ofenergy budget components above the pine forest. The
latent heat flux indicated high values, 50 - 100 Wm-2
even at the beginning of May. Consequently, the seasonal variation of Bowen ratio did not show “U-shape”
as that in the larch forest shown in Fig. 5 during theobservation period.
Figure 7 shows the spatial and temporal distributions of soil temperature at the larch and pine forests.
The thawing depth reached up to 60 - 80 cm depth at
the beginning of May in the pine forest. On the other
hand, the thawing depth was only 10 - 20 cm depth
even at the beginning of June in the larch forest. Pine
stands were evergreen and the thawing of permafrost begun early in the pine forest. Consequently, transpiration activity became high in a nearly spring in thepine forest.

3.2 Seasonal and inter-annual variation of energy
budget of larch forest
Figure 4 shows the seasonal variation of the sensible heat flux from 1998 to 2000. The sensible heat
fluxes had maximal values at the end of May when it
was just after a snow ablation, every year. The sensible heat fluxes decreased gradually ups to August,although the effective radiation increased until the endof June.
Figure 5 shows the time series of energy budget
components above the larch forest in 1998. The energy incoming and outgoing were not balanced in thissite, and the relationship between the avilable energy(Rn-G) and the sum of turbulent heat fluxes (H + lE)
was presented as a following equation,
H + lE = 0.752 (Rn-G)
where Rn is the net radiation, G the ground heat flux,
H the sensible heat flux, and lE is the latent heat flux.
The latent heat flux increased rapidly when larch stands
begun to foliate. On the other hand, the sensible heat
flux dropped at that time. According to these results,
the latent heat flux might have the same as that in1998. This result showed that the plant physiologicalactivity affected the seasonal variation of energy budget strongly.
The canopy resistance in the Penman-Monteith for-

3.4 Water flow and balance at the surface
Transpiration from the larch stands, not including
evapo-transpiration from under-story vegetation, wasestimated using a heat pulse method. The amount oftranspiration was similar in two years, although there
was a significant difference of precipitation. The result suggests that the soil moisture did not control transpiration and that transpiration was affected by atmospheric condition.
The percentages of stem flow to precipitation at
the open site were less than 1 % in the larch and the

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22
-2

250
200

Net radiation(a)Ground heat flow
including snow melt

150
100
50
0
250

-2

Flux density (W m )GAME Letter No. 3

200

Sensible heat flux(b)

Latent heat flux

150
100
50
0
25

Bowen ratio

(c)

20
15
10
5
0

April

May

June

July

Snow free& leafless

Aug.

Sep.

FoliatedOct.
1998
Surfacecondition

Snow covered

Opening leaves

Falling leaves

Seasonal variations of the energy budget and the Bowen ratio
above a larch forest at Spasskaya Pad, Eastern Siberia

Fig. 5. Seasonal variation of each component of energy budget and Bowen ratio at above the larch

400

0

300

Net radiation
Latent Heat
Sensible Heat
Ground Heat
Precipitation

200

10
20

100

30
0
May

Apr.

25
1998
1999
2000

100

50

July

August40

20
Bowen Ratio

Sensible Heat Flux (W m-2 )

150

June
2000

Precipitation (mm day-1 )forest in 1998. (Ohta et al., 2001)

Flux Density (W m-2 ）pine forests. On the other hand, the percentages ofthrough fall were around 15-25 % in the both forests,
so under-story precipitation consisted of only throughfall. The interception rate was around 15 % of thegross precipitation in the larch forest.
Snow adds complexity in the seasonal sequence ofwater flow at the surface. Maximum snow depth was
25 to 45 cm in this area. During the first half of thawing season, it was estimated that 40 % of the surface
snow melt water percolated in to the frozen permafrost, although snow temperature was below the freezing point in almost layer. It was considered that thesnow melt water flowed down through snow fingers
formed in a snow pack.
Water balance in a at this larch forest for the warm
season, including a snow-melting period, in1998 is asfollowed. Total water input was 211 mm. 105 mm oftotal input consisted of snowmelt water, and 106 mm
was precipitation during the warm season. Evapo-transpiration from a whole ecosystem was 151 mm, andthe under-story evapo-transpiration was equal to 35% of total evapo-traspiration. The interception evaporation, 16 mm, was 15 % of the gross precipitation at
the open site. The total evapo-transpiration exceeded
the total precipitation, and snowmelt water compensated for this deficit.

Flux density (W m )Oct. 2001

15
10
5

0

April

May

June

July

AugustSeptember

0 Apr.

May

June

July

Aug.

Sep.

Oct.

2000

Fig. 4. Seasonal variation of sensible heat flux above
the larch forest.

Fig. 6. The seasonal variations of energy budget
components and Bowen ratio above the pine forest in 2000.

AME

GAME Letter No. 3

23

Oct. 2001

0

D ep th (cm )

-20
-40
-60
-80
-100
-120

2

3

4

5

6

7

8

9

Month of 1998
0Tg ( o C)
-20

)
m
c
(
h
t
p
e
D

35.0
32.5
30.0
27.5
25.0
22.5
20.0
17.5
15.0
12.5
10.0
7.5
5.0
2.5
0.0
-2.5
-5.0

-40

-60

-80

-100

-120

May

June

July

AugustMonth of 2000

Fig. 7. Spatial and temporal distribution of soil temperature at the larch site in 1998 and at the pinesite in 2000.

4. Intensive observation for spatial heat/waterexchange in year 2000.
In year 2000, additional surface observation network was prepared in the Yakutsk area including a
tower which was set in the taiga forest at the leftbank of Lena River since 1997 (Sec. 2), to evaluate
the heterogeneity of surface heat/exchange and spatial evaluation introducing the aircraft measurements.
Observational network and flight courses are shownin Fig. 8.
4.1 Surface studies in right bank of Lena
4.1.1 Objectives for study and description of the
area
There is a large number of sporadic grassland especially in the right bank of the Lena River inside theforest. These grasslands are called “alas”, occupying up to 20 % of this area. The alas is a concave

landform that is formed after the forest has beencleared in an area where the ice content of permafrost was high. Usually the alas has a lake near thecenter of it. The field campaign of the year 2000 was
carried out from April to September 2000, in an alas
site near Tungulu village in the right bank of the Lena
River.
The main objectives of this research are as follows:(1) To characterize the one-dimensional water, energy, and CO2 fluxes over the three typical land
surfaces, that is, young larch forest, alas grassland, and alas lake.
(2) To clarify the difference in the surface energybalance between alas grassland and the forest floor,
and to determine the moisture and thermal regime
in the active layer at each site that reflect the surface energy condition.
(3) To learn how the water balance components affect the seasonal and inter-annual variation in water level/area of the alas lake.
The observation site in the right bank of the Lena
River is called “Ulakhan Sykkhan”, and is a publicalas, located 8 km west of the Tungulu village. It isoval-shaped, and is 1200 m long from west to eastand 600 m long from north to south. It has an area of
0.64 km2, including a 0.1 km2 lake at the center. A 23
m high PBL tower in the young larch forest and asingle mast system was set up at the center of alas
grassland. Measurement on heat/water exchange wasmade at forest, grassland and lake.
These observations were made intensively between April and June 2000, in conjunction with theregional flux observations from the aircraft, then regularly from July to September.
4.1.2 Brief results(1) Difference of seasonal change in energy flux among
forest/grassland/lake surface (Fig. 9.)- Net radiation: forest = grassland = lake

AME

24
- Sensible heat: forest » grassland > 0, | lake | >grassland- Latent heat: lake > forest > grassland > 0(2) Difference in the surface energy balance between
grassland and forest floor- Solar radiation: floor/canopy = 0.4- Soil heat flux: forest/grassland = 0.5 (Fig. 10.)
However, small soil heat flux value at the forest isalso depending on the insulation effect of the litter
layer on the forest floor.
(3) Unique water balance of the alas lake (Table 3)
Lateral groundwater inflow/outflow component during the summer seems to be very small. It meansthat vertical components, precipitation and evaporation, are more important for the lake water balance. Because the lake water-level/area showsits maximum in just after the snowmelt period anddecreases continuously after that, its inter-annual
variation is mainly dependent on the snow storage
volume in each year.
4.2 Spatial observation by aircraft
Aircraft observation in Yakutsk area (Eastern Siberia) was performed from April to June 2000. The
object of investigations was ABL over Lena river andsurrounding area and specially equipped Russian built
ILYUSHIN-18 aircraft was used for observations.
Main study topics were, spatial distribution of meteorological elements, sensible/latent heat and water vapor flux, atmospheric boundary layer structure, isotopic composition of water vapor at an altitude from100 to 4000 m in the flight area shown in Fig. 8.
The aircraft was ILYUSHIN-18 operated by CAO,
and it was equipped with the GPS, device for measuring dew-point temperature, system for measuringhigh response fluctuations of the horizontal/longitudinal wind respect to flight direction and vertical components of wind speed, high response temperature
sensor, high response humidity sensor, high response
closed-path CO2/H2O gas analyzer, infrared radiometer thermometer and video camera.

Oct. 2001

GAME Letter No. 3

According to the schedule of observation days andthe real weather conditions the experimental flights
were made on April 24, May 1, 9, 12, 20, June 1, 5, 9
and 19, 2000. Each of these nine flights was madepunctually according to the scheme.
Main results will be presented.
(1) Large variability of meteorological and turbulent
conditions in the studied area:
Surface underlying of regional legs (NW to SE)
can be divided into 4 parts with different and relatively uniform (with respect to whole regional leg)structure. Each part of surface had the horizontal
length about 20-22 km. Part #1 was located over pine
and larch forest at the left bank of Lena River, Part
#2 was chosen over Lena valley and Lena River. Part
#3 of surface belonged to the right bank and consisted of mainly larch forest and grass fields and Part
#4 (right bank) had complex profile with small hills
covered with forests. The data obtained over thesefour parts of surface were taken into the analysis of
the CBL models application.
Examples of obtained turbulent data (horizontal andvertical wind speed fluctuations, air humidity and airtemperature fluctuations both with surface temperature and structure of underlying surface) and schemeof dividing the flight path are presented in Fig. 11.
(2) Distribution of fluxes are variable in the area:
Flights over grid sampling area at the left and rightbank sides of Lena River at a height of 100 m allowed
to obtained horizontal distributions of turbulent sensible and latent heat fluxes and carbon dioxide fluxes.
Examples of such horizontal distributions for flightmade on May 1 are presented in Fig. 12 .
Data obtained during measurements on grid legs at
a height of 100 m were the base for calculating square
averaged turbulent fluxes. This gave possibility to estimate seasonal variations of sensible and latent heat
fluxes and carbon dioxide fluxes. Results of aircraft
observed and averaged fluxes are shown in Fig. 13.
Seasonal variations of surface temperature and potential virtual temperature are also presented.

AME

GAME Letter No. 3

25

Oct. 2001

1) there were no any internal sub-layers. Example ofvertical sounding of CBL on two days without TIBL(May 1 and June 1) and with TIBL (June 9 and 19) ispresented in Fig. 15
Spectra of coherence between vertical wind speed
fluctuations and air temperature fluctuations also proveexisting of TIBL developed in CBL through the total
depth. These spectra obtained on May 1, June 1, 9
and 19 at the different height from 100 m up to 1500
m show clear differences between spectra of coherence at Part #2 for the days with and without TIBL.
Threshold value of 0.15 for spectra of coherence wasexceeded only on days without TIBL
Distributions of wavelet coefficients (or wavelet
spectra) allow us to get not only existing of some events(heterogeneity zones of turbulent fluctuations), but also
its locations in space (along the flight path) and scales(wave numbers). Wavelet spectra were the base forcalculating distributions of wavelet variances or
scalograms, which are the analogs of Fourier spectra.

Observations made on regional flights allowed us
to get spatial distributions of turbulent sensible andlatent heat fluxes and carbon dioxide fluxes. These
distributions for flight days of May 1, June 1 and 19,
which we named as fine spatial structure of fluxes
are presented in Fig. 14. These pictures also give image about seasonal variations of fluxes in Yakutsk region.
(3) Different characteristics of the ABL in the left
and right bank:
Vertical sounding of ABL over left and right banksof Lena River showed:-ABL during all 9 days of observations can be treatedas convective boundary layer (CBL)-During 5 flight days (on May 12 and 20, June 5, 9
and 19) development of thermal internal boundary sublayers (TIBL) through the total depth of the CBL wereobserved. These also proved by fine spatial structureof potential virtual temperature, specific humidity, sensible heat and latent heat fluxes (see figs. 5 -7). On
the others flight days (on April 24, May 1 and 9, June

Fig .8. The map showing the position of ground station during the intensive observation year 2000 and the flightcourse made from April to June. The shaded area in the map is the grasslands,and Lena River runs south-northat the center.
A-D : Radiation and precipitation and precipitation sampling
R1-R8 : Precipitation and precipitation sampling
W0-9 : Alas and lake water sampling

LAI : Leaf Area Index

T11-21 : Surface soil moisture measurement with TDR (1*)

T : Observation tower at Spaskayapaid and alas station(1*) Surface soil moisture was also observed at another sites for radiation and/or precipitation observation sites

AME

26

Oct. 2001

0

Forest Canopy

Energy Flux (W m )

300

-2

Grassland (W m )

-2

200
Rn
H
lE
G

100

0

-100
4/18

5/3

5/18

6/2

6/17

7/2

7/17

8/1

8/16

8/31

9/15

Alas Grassland

Energy Flux (W m )

300

-2

200

100

-10
-20
-30
-40

Rn
H
lE
G

-40

-30

4/18

-10

0

-2

5/3

5/18

6/2

6/17

7/2

7/17

8/1

8/16

8/31

Fig. 10. Comparison of soil heat flux between forest

9/15

and grassland at the Alas area in the summer

Alas Lake
300

Energy Flux (W m )-20

Forest (W m )

0

-100

-2

GAME Letter No. 3

season. Negative value show that heat is conducted into the ground from the surface

200
Rn
H
lE
dQ

100

0

6
3
0
-3
-6

-100
4/18

5/3

5/18

6/2

6/17

7/2

7/17

8/1

8/16

8/31

9/15

6
3
0
-3
-6

Fig. 9. Seasonal change in daily mean energy fluxes
over the forest/grassland/lake in the Alas area.

4,5

Horizontal wind speed fluctuations, m/s

Vertical wind speed fluctuations, m/s

Absolute air humidity, g/m3

4,0
3,5
18

Air temperature, oC

16
14
40

Table 3. Result of water balance on the alas lake

Surface temperature, oC

20

Wind

during the observation period.

0

Table 3. Result of water balance on the alas lake during the observation period.
Period21 May –

Δt
days

Δh
mm

P
mm

E
mm

Qi·Δt/A
Mm

111

-288

129

451

34

9 Sept.

Lena valleyHill

8.8 m/s

Field

Lena river

10

20

#1

30

40

#2

50

60

#3

257 m
70

80

Distance,
km
90

#4

Fig. 11. The meteorological and turbulent elements
at 100 m along the regional leg (NW to SE) during

Water balance equation on the closed lake is as follows:
A·Δh = ( P – E ) · A + Qi·Δtwhere, A : surface area of the lake, Δh : changes of water level,Δt : duration, P : precipitation, E : evaporation, andQi : rate of surface/subsurface inflow.

the flight on May 1.

AME

GAME Letter No. 3

27

Oct. 2001
Flight on June 1
Carbon dioxide fluxes, mg/m2 s

Flight on May 1, left bank, 100 m
Carbon dioxide fluxes, mg/m2s

1500

2.40 -- 3.00
1.80 -- 2.40
1.20 -- 1.80
0.600 -- 1.20
0 -- 0.600-0.600 -- 0
-1.20 -- -0.600-1.80 -- -1.20-2.40 -- -1.80-3.00 -- -2.40

1000

62,32
62,30

500

2.00 -- 2.50
1.50 -- 2.00
1.00 -- 1.50
0.500 -- 1.00
0 -- 0.500-0.500 -- 0
-1.00 -- -0.500-1.50 -- -1.00-2.00 -- -1.50-2.50 -- -2.00

62,28

1500

62,24
62,22

Latent heat fluxes, W/m2

Latent heat fluxes, W/m2
240 -- 300
180 -- 240
120 -- 180
60.0 -- 120
0 -- 60.0-60.0 -- 0-120 -- -60.0-180 -- -120
-240 -- -180
-300 -- -240

1000

Height, m

62,26

0

500
0
1500

Sensible heat fluxes, W/m2

62,32

240 -- 300
180 -- 240
120 -- 180
60.0 -- 120
0 -- 60.0-60.0 -- 0-120 -- -60.0-180 -- -120
-240 -- -180
-300 -- -2401000
240 -- 300
180 -- 240
120 -- 180
60.0 -- 120
0 -- 60.0-60.0 -- 0-120 -- -60.0-180 -- -120
-240 -- -180
-300 -- -240

62,28
62,26

500

Wind=8.9 m/s
0

332o

30
Tsuf, oC

Latitude, o

62,30

62,24

Lena valley

Hill

Field

Lena river

20
10 0

10

20

30

40

50

257 m

60

70

80

90

100

Distance, km

62,22Sensible heat fluxes, W/m2
62,32
62,30

Fig. 14. The vertical distribution of fluxes along the

240 -- 300
180 -- 240
120 -- 180
60.0 -- 120
0 -- 60.0-60.0 -- 0-120 -- -60.0-180 -- -120
-240 -- -180
-300 -- -240

62,28
62,26

regional leg flight on June 1.

62,24
62,22
129,3

129,4

129,5

Wind=9.
0 m/s

129,6

Logitude,

129,7

129,8

129,9

o

5000

Fig. 12. Spatial distribution of CO2, sensible/latent

Without TIBL P >1
May 01 s

With TIBL P <1
June 09 s

June 01

June 19

4000
3000

heat on May 1 at the right bank.

2000

30
20

right

30

surface temperature
virtual temperature

29
28
28
27

0

0
5000
4000
3000
2000

0,

1000

0,

0

-0,

280288296304312

0 2 4 6 8 101214,Kq, g/kgθ-1,

Sensible heat2 fluxes, Latent heat fluxes,Wm
Wm 2

Co 2 fluxes,
mg/m 210Height, m

left

Virtual temperature ℃

Surface temperature,℃

1000

280288296304312

θleft bank,K

0 2 4 6 8 101214

q, g/kgright bank40
20

Fig. 15. Vertical profile of potential temperature and0

specific humidity of CBL on two days without

20
15
10
50
0
21 Apr 28 Apr 5 May 12 May 19 May 26 May 2 Jun

and with TIBL.

9 Jun

16 JunDaysFig. 13. Seasonal variation of meteorological elements and fluxes at the right and left bank. The
values are area average.

AME

28
5. Large scale analysis using 4DDA and satellite
data
5.1 Water circulation study of the atmosphere/
land system.
Water budget study of the Lena River drainage wasmade using ECMWF and other global datasets. Results showed that there may be a lag in the precipitation and evaporation in these area for two years, evaporation proceeding the precipitation. The reason of thismay be the influence of water storage and releasesystem in the permafrost zone. However, there need
to be more analysis to be made, since surface observation (patch scale such as the one at Spasskaya) ofwater fluxes shows rather small inter-annual variation.

5.2 NDVI analysis
Two analysis was mostly advanced with the use ofsatellite data. One was on vegetation using NDVI data
and the other was snow cover estimation using microwave data.
The difference in the reflectance of chlorophyll pigment between the visible and near-infrared parts ofthe spectrum provides a means for monitoring thedensity and vigor of green vegetation. The Normalized Difference Vegetation Index (NDVI), a wellknown vegetation index, is computed as NDVI =(Ch2Ch1)/(Ch2+Ch1), where Ch1 and Ch2 are the surface reflectance from AVHRR Channels 1 and 2, respectively.
In summer, a zonal (west-east) high NDVI belt isfound around 60N where a taiga forest flourishes inSiberia. By contrast, its southern and northern regions are characterized by a low NDVI due to arid
climate and tundra climate, respectively. To examine
these meridional changes, two meridional (south-north)transects were established, i.e., the arid-taiga transect(along 75E) and the taiga-tundra transect (along 110E)
in Siberia (Suzuki et al., 2000). The meridional profile
of annual mean NDVI, annual precipitation andOct. 2001

GAME Letter No. 3

warmth index (a cumulative temperature of monthly
mean temperature above 0C) were compared. In
arid-taiga transect, as indicated in Fig. 16, a strong
positive correlation between NDVI and precipitation
meridional changes, and a negative correlation between the NDVI and warmth index were found. From
this result, it was suggested that aridity is the limiting
factor for the vegetation amount in this transect.
In taiga-tundra transect, a strong correlation was
found between the NDVI and warmth index meridional changes, suggesting that the limiting factor istemperature. Furthermore, it was revealed that thetemperature spatial variation due to station’s elevation causes a NDVI variation. This fact suggests thatthe vegetation is quite sensitive to the temperature
regionality.
Another study was done on vegetation regionality
and its climatological implication over an extensive
region of Siberia and surrounding areas, from a plant
geographical stand point of view (Suzuki et al. , 2001a).
By the cluster analysis, the NDVI seasonal cycles at
611 stations were classified into 10 classes (A, B, C,
D1, D2, E1-E4, F) and it was suggested that each
local region contains vegetation with a distinct phenological cycle. It was revealed that the high NDVI iszonally distributed mainly in the latitudinal lines from50 to 60N, and this zone roughly coincides to the zone
where the annual maximum monthly temperature isaround 18C. From this result, it can be consideredthat the zone where the maximum temperature isaround 18C has climatologically the greatest potential
for the highest NDVI.
As for local area where intensive observation of2000 were made, analysis for April 1992 to September 1993 was made (Suzuki and Ochi, 1999; Suzuki,2000). It was revealed that the NDVI regionality
should be partly characterized by the land cover type
and topography. However, the NDVI indicates regional variations which do not correspond to both topography and land cover. Those unknown factors of
the NDVI regionality should be focused by the future

AME

GAME Letter No. 3

Oct. 2001

work, such as airborne field observation.
Photograph observation was carried out at a station Spasskaya Pad to record the forest/snow condition and phenological transition from August 25, 1997
up to October 15, 2000. In the winter season, the frequency was reduced. The time of major event of theforest was roughly revealed by the photographs.
5.3 Snow cover study
Snow cover distribution was studied using microwave signals of SSM/I for the north-east Eurasianpart. The brightness temperature difference（? T）
between 19 and 37 GHz were taken as index for snow
depth. The seasonal change in ? T was able to be classified into 9 types. There were areas where snow
depth can be estimated by ? T rather well throughout
the winter, but some region had bad relation. Forest
conditions, absolute value of snow depth and snow
texture seemed to have influence on this relation.

Fig. 16. Meridional profiles of the warmth index(WI(0)), annual precipitation, and the annual
mean NDVI in 75 and 110E-transects

29
6. Modeling
6.1 One-dimensional models
Objectives of these models are estimating energy
and water fluxes over various land surfaces, understanding of meteorological and hydrological processes
and clarifying flux dependence on vegetation and terrain. A model, which was developed for intensively
cold regions including vegetation, snow and soil layers, has been adapted to the plain taiga site. In 1998,
diurnal and seasonal variations of fluxes are simulated
reasonably, however, snowmelt is slightly earlier thanobservation. Another model, which was developed tocouple with GCM or regional climate model, has been
adapted to the tundra site (off-line simulation). In addition to these two simple models, two kinds of model
have been developed to simulate CO2 transfer andvertical fine structure of profiles. Remaining subjects
are as follows: water flow in snow and soil, especiallywater channel in snow and water flow in frozen soil,
and comparison with other site including right bank ofLena River.
6.2 Coupling one-dimensional models with atmospheric models
Preliminary results are obtained on simulation of athunderstorm in 1998 near Yakutsk using a regional
atmospheric model (RAMS). The followings are subjects in the near future: to estimate regional flux distribution and compare with aircraft observations, andto simulate precipitation events including cloud formation and comparison between left and right bankof Lena River.
6.3 Hydrological models
A macro-scale hydrological model combined witha simple SVAT model has been adapted to whole Lena
River (Ma et al., 2000). When considering the effectof river freezing, seasonal change of runoff has been
simulated reasonably. Remaining subject is long-term
simulation to understand inter-annual variation. Twomodels joined the “Intercomparison of hydrologicalmodels” of PILPS-2e which is presently going on, and

AME

30
succeeded in getting good results.
7. Concluding remarks
The Siberia group had its main observation period
in 2000, and the southern Taiga area only was able toimplement its observation in 2001. Therefore, one or
two more years are needed to elucidate major results.
7.1 Major scientific results
Although analysis is going on, there have been new
findings up to now. The main ones are:
(1) Understanding advanced on the annual rhythm of
the heat/water exchange at typical Siberian forest(larch and pine) using sophisticated observation systems. The amount and the timing of the heat/water fluxes especially from April to September were
understood in more detail, comparing to the several observation done in the past (Pavlov, 1984).
The absolute evaporation amount is smaller thanpreviously estimated and it can be said that thephysiological characteristics of the vegetation determine the heat/water balance at patch scale andeven at larger spatial scale.
(2) In tundra area, the amount of summer runoff seemto be regulated rather strongly on the distributionof winter snow cover, compared with Alaskancases owing possibly to topography and wind climate. Also the difference of evaporation on low
and high precipitation year does not differ much.
(3) Spatial distribution of regional sensible/latent heat(vapor) fluxes and ABL are complex due to influence of topography, land surface condition anddynamic response of atmosphere. The possibility
that surface fluxes is partly regulated by atmospheric response was shown.
(4) The inter-annual variability of summer evaporation was obtained by a surface network and 4DDA
analysis data, and they show rather contradicting
results up to now.
(5) From NDVI analysis vegetation characteristics
show latitudinal distribution implying zone of highOct. 2001

GAME Letter No. 3

vegetation activity. It will be interesting to knowwhether it is reflected in the heat/water exchange
on land surface.
(6) Complexity of obtaining snow data from microwave information in Siberia region was shown.
(7) Through the application of various models to theobservational and newly collected operational data,
the models were improved, and in some cases, they
were validated to be a good model.
7.2 Publication, international relations and contributions
The Siberia group has made following otherprogress.
(1) Our group has already published several project
results, review monographs and papers listed at
the end of this section.
(2) The Japanese research group has held approximately 15 domestic meetings since 1994 to discuss projects and its results.
(3) As part of interaction with foreign scientists andcommunities, we held two international workshop
with Russian and scientists from other countries(Fukushima and Ohata, 1997; Ohata and Hiyama,
1998). Another direction was to hold scientificmeeting with MAGS group, another continental
experiment in clod region within the framework of
GEWEX (MAGS and GAME, 2000) . The second of such meeting is planned in October, 2001.
(4) Members of the Siberia Group has attended SSGs
of international project such as ACSYS/CLIC,
IGBP-BAHC to have interference with them.
Publications(Publications up to now: Individual reports and papers
in the Activity Reports of GAME-Siberia, GAME
Conference Proceedings and GAME-Siberia Workshops are omitted)
Fukushima, Y. and Ohata, T. (Eds.) (1997): Proc. International Workshop on Energy and Water Cycle in Siberia, 1995. IHAS Report, No. 3, 96pp.

AME

GAME Letter No. 3

31

Oct. 2001

GAME-International Science Panel (1998): GEWEX International Implementation Plan. 136pp.
GAME Interntional Science Panel (1997): Proc. The Third

T. (2000): A macro-scale hydrological analysis of the
Lena River basin. Hydrological Processes, 14 (3), 639651.

International Study Conference on GEWEX in Asia

MAGS Science Committee and Japan National Committee

and GAME (Cheju, Korea., March 26-28, 1997),

for GAME (2000): Proc. the GAME-MAGS Interna-

468pp.

tional Workshop, Nov. 25-27, Edmonton, Canada.

Georgiadi, A.G. and Fukushima, Y. (Eds.) (1999): Water andenergy cycle in permafrost regions of Eastern Siberia.
IHAS Report, No. 6, 265pp.
GEWEX (1999): Preprint Volume of Third International
Science Conference on the Global Energy and Water

170pp.
Ohata, T. and Hiyama, T. (Eds.) (1998): Proceedings of Second International Workshop on Energy and Water
Cycle in GAME-Siberia, 1997. , IHAS Report, No. 4,
181pp.

Cycle jointly with the fourth study Conference on

Ohta, T., Hiyama, T., Tanaka,H., Kuwada, T. and Maximov,

GEWEX Asian Monsoon Experiment(GAME)

T.C. (2000): Seasonal variation in the energy and wa-(Beijing, China, June 16-19, 1999). 560pp.

ter exchanges above and below a larch forest in east-

Hiyama, T., Ohta, T., Suzuki, K. and Sugimoto, A. : Diurnal

ern Siberia. Hydrological Processes, (accepted).

variation of surface energy fluxes and its impact on

Suzuki, R., Tanaka, S. and Yasunari, T. (2000): Relationshipthe lower atmospheric boundary layer over eastern

between meridional profiles of satellite-derived veg-

Siberia. Agricultural and Forest Meteorology (sub-etation index (NDVI) and climate over Siberia. Int. J.

mitted)Climatology, 20, 955-967.

Japan National Committee for GAME and National Research

Tanaka, H., Ohta, T., Hiyama, T. and Maximov, T. (2000):

Council of Thailand (1995): Proc. the Second Interna-

Seasonal variation of photosythesis and transpiration

tional Study Conference on GEWEX in Asia andproperties of a boreal deciduous forest: Analysis us-

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GAME Letter
Published by the GAME International Project OfficeProf. Kenji Nakamura, Director
Editors: Dr. Atsushi Higuchi, Ms. Yuri Tanaka and Ms. Tomoko Tanaka
Hydrospheric Atmospheric Research Center
Nagoya University
Furocho, Chikusaku, Nagoya 464-8601, Japan
Phone: +81-52-789-5439, Fax: +81-52-789-3436
E-mail: gio@ihas.nagoya-u.ac.jp, URL: http://www.ihas.nagoya-u.ac.jp/game/index.html