NAME =  Yukiko Hirabayashi  
ORGANIZATION =  University of Yamanashi  
ADDRESS =  4-3-1 Takeda, Kofu-shi, Yamanashi  
COUNTRY =  Japan  
PHONE =  +81-55-220-8728  
FAX =  +81-55-253-4915  
E-MAIL =  hyukiko@yamanashi.ac.jp  
POSTER_ONLY =  yes  
THEME =  T7  
DATE =  30-Jul-04-18:11:44  
ABSID = T7YH30Jul04181144 
TITLE = Estimation of global hydrologic components in the 20th century 
AUTHOR_1 = Yukiko Hirabayashi 
INSTITUTION_1 = University of Yamanashi 
PRESENTER = AUTHOR_1 
AUTHOR_2 = Shinjiro Kanae 
INSTITUTION_2 = Research Institute of Humanity and Nature 
AUTHOR_3 = Taikan Oki 
INSTITUTION_3 = IIS, University of Tokyo 
AUTHOR_4 = Kuniyoshi Takeuchi 
INSTITUTION_4 = University of Yamanashi 
ABSTRACT =  A 100-year (1901-2000) off-line simulation by a land surface model (LSM) has been completed by obtaining 100-year atmospheric forcing data sets from available global observations. It was found that the long-term terrestrial water fluxes can be estimated well from a LSM driven by long-term atmospheric forcing data that was stochastically estimated from monthly mean time series of precipitation and temperature. High correlations of annual runoff variations are obtained at many basins globally, however, the correlations of annual runoff are low in dry areas. Low correlations are also obtained in cool-temperate zones. Annual snow covered area in North America and the model successfully replicated northern Europe and annual summer soil moisture in Mongolia. Several trends indicated by previous studies, the descending trend of snow covered area in northern America and Europe and the increasing trend of summer soil moisture in Mongolia were also appeared in the simulation. With the benefit of 100-year simulation results for these variables, however, these trends appear to be within a range of natural long-term variability rather than systematic changes in hydrological condition. The 100-year estimation of hydrological component, such as annual and inter-annual variation of runoff, snow and soil moisture, would be useful for examining behaviors of a LSM with a perspective of long-term variations. They are also useful for water resources assessment rather than short-term estimation, because of the inclusion of several extremes and longer natural variability. It is also useful to obtain long-term hydrologic component especially for less-observed variables or in poorly-gauged basins; they can be used as a reference data to check GCMs and LSMs and water resource assessment in un-gauged basins.