KOIKE Toshio

Tsukuba Repository

Status report on the GAME Water and Energy
Budget Study (GWEBS) (Session 2: GAME Water
and Energy Budget studies)
著者 KOIKE Toshio
journal or
publication title
Bulletin of the Terrestrial Environment
Research Center, the University of Tsukuba,
Proceedings of the International Workshop on
GAME-AAN/Radiation
volume 1
number 別冊
page range 24-24
year 2001-03
URL http://doi.org/10.15068/00147166
Status report on the GAME Water and Energy Budget Study (GWEBS)  
Toshio Koike, Department of Civil Engineering, University of Tokyo 
7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan 
phone:+81-3-5841-6106, fax:+81-3-5841-6130, E-mail:tkoike@hydra.t.u-tokyo.ac.jp 
 
To close the energy and water budgets in 
each CSE is inevitable for identification of 
characteristics of each region in the global 
climate systems and investigation of heat and 
moisture source and sink and their seasonal 
and interannual variations. Each component of 
energy and water balance equations in 
atmosphere and at land surface should be 
estimated with high accuracy and validated 
independently for closing budgets. A unified 
method should be adopted for inter-comparison 
of energy and water budgets among the all 
CSEs. 
In the GAME four regional experiments, 
monthly basis budget closure is proposed 
based on the GAME-IOP data in 1998. There 
are five components, precipitation, moisture 
convergence, evaporation, water storage 
variation and runoff, which should be estimated 
independently as follow:  
 
1) Precipitation: A combined product by using 
satellite / rain gauge / ground-based radar is 
generated. Mutual cooperation with GPCP, 
NASDA and JMA is expected. 
2) Moisture convergence: The GAME-IOP 
reanalysis is now available. The results of the 
reanalysis is used for estimation of moisture 
convergence in the GAME. 
3) Evaporation: The moisture flux data at each 
flux measurement site of the four regional 
experiments is used as a point data. A land 
surface scheme, which is modified and 
evaluated by using the observed data, is 
used for estimation of region-wide moisture 
flux distribution by inputting a forcing data set 
generated by using the interpolated and/or 
extrapolated observed data. The 
complementary-relationship method is 
adopted for estimation of evaporation in 
region scale. Well-validated radiation budget 
at land surface is expected in cooperation 
between each CSE and ISCCP. The land 
surface meteorological data obtained by each 
CSE is used.  
4) Water storage variation: It is difficult to 
estimate water storage variation directly. It 
can be calculated as residual term of the land 
surface water balance equation. In some 
region, the estimated value can be validated 
by using the ground based soil moisture 
networks. In the other region, satellite 
products of surface soil moisture can be used 
for confirmation of consistency of estimated 
values to the actual situation. The 
satellite-based snow data set can be used for 
quantitative validation. 
5) Runoff: The observed runoff data should be 
collected. Seasonal and interannual 
anomalous states can be identified after 
removing the artificial effects due to river 
control. 
 
The following figure shows an example of the 
inter-comparison of seasonal march of heat 
budget at the four flux sites. The convergence 
data obtained by the reanalysis will be overlaid.  
 
0
2
4
6
8
60 80 100 120 140 160 180
Rn [w/m2]
B
o
 
=
 
H/
L
E
Jun.
July
August
Sukothai
Amdo
Shiquanhe
Arvaikheer
Seasonal march
…••~ 
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Status report on the GAME Water and Energy Budget Study (GWEBS) (Session 2: GAME Water and Energy Budget studies)

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