Abstracts for the 5th International GAME Conf.
3-5 October 2001
Aichi Trade Center
Nagoya Japan
Orographic Rainfall in a Tropical Mountainous Region, the Southeast Asia
Koji DAIRAKU (1), Seita EMORI (2), Shinjiro KANAE (1), Taikan OKI (1), Katsumi MUSIAKE (1), Kowit PUNYATRONG (6), Wathana SUKURNJANASET (7)
(1) Institute of Industrial Science, The University of Tokyo
(2) Atmospheric Environment Division, National Institute for Environmental Studies
(6) The 7th Watershed Management Center, Royal Forest Department, Thailand
(7) Bureau of Royal Rainmaking and Agricultural Aviation, Thailand
Atmospheric circulations are often caused by or strongly affected by the spatial variability of land surface characteristics. In order to understand the temporal and spatial variability of rainfall characteristics, the ground-based rainfall observation in a mountainous area as a part of GAME-Tropics in Thailand, has been continuing since the late 1997. So far, the high resolution precipitation records like hourly or less are limited to a few experimental stations in tropical or subtropical region. Thirteen rain gauges with sub-hourly (1 min) time resolution were installed from about 380 to 2500 m above sea level (a. s. l.) in the Mae Chaem watershed with the area of 3853 km2.
It is clear that the rainfall amount varies according to elevation in this watershed throughout the rainy season. It becomes clear that the increase of rainfall amount correlates to the increase of rainfall duration, regardless of the method used to calculate it, whereas the increase of rainfall amount is not correlated with that of mean rainfall intensity. The increase of rainfall amount associated with altitude in this mountainous area is correlated with increases in rainfall duration and independent of increases of mean rainfall intensity.
The Regional atmospheric Modeling System (RAMS) is used to perform simulations of the distribution of precipitation in this mountainous region. The results indicated that the mountain has a important role to trigger cumulus convection and that horizontal and vertical differential heating can lead to the development of mesoscale circulations. Model simulations are validated against the rainfall observations, and with a particular focus on the interaction between precipitation characteristics and land surface conditions.
Submittal Information
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Institute of Industrial Science, The University of Tokyo | |
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Be605 Institute of Industrial Science, University of Tokyo 4-6-1 Komaba Meguro-Ku Tokyo 153-8505 Japan | |
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dairaku@iis.u-tokyo.ac.jp | |