NAME =  Koji Dairaku  
ORGANIZATION =  National Institute for Environmental Studies  
ADDRESS =  16-2 Onogawa Tsukuba Ibaraki 305-0053  
COUNTRY =  Japan  
PHONE =  +81(29)-850-2102  
FAX =  +81(29)-850-2960  
E-MAIL =  dairaku.koji@nies.go.jp  
POSTER_ONLY =  yes  
THEME =  T2  
DATE =  28-Jul-04-17:38:18  
ABSID = T2KD28Jul04173818 
TITLE = Observation and numerical experiments of orographic precipitation in the Mae Chaem watershed in Southeast Asia 
AUTHOR_1 = Koji Dairaku 
INSTITUTION_1 = National Institute for Environmental Studies 
PRESENTER = AUTHOR_1 
AUTHOR_2 = Seita Emori 
INSTITUTION_2 = National Institute for Environmental Studies 
AUTHOR_3 = Taikan Oki 
INSTITUTION_3 = Institute of Industrial Science, the University of Tokyo 
ABSTRACT =   A dense tipping-bucket rain gauge network was established in the Mae Chaem watershed in the mountains of northwestern Thailand as part of the Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment-Tropics (GAME-T). Investigations of rainfall amounts, intensities, durations, and frequencies in the rainy season revealed strong orographic rainfall enhancement in the region. The larger amount of high-altitude rainfall was attributed to duration and frequency rather than intensity. By investigating orographic precipitation using a regional atmospheric model, the duration and frequency of rainfall at high altitudes were found to be caused by two mechanisms: 1) convective clouds over mountains activate in the evening, and 2) seeder-feeder mechanism caused by strati formed by radiative cooling or heating in the middle troposphere and orographically triggered low-level convective clouds. The results of a numerical simulation were quite consistent with the measurements acquired from the tipping-bucket rainfall gauges.