Abstracts for the 6th International GAME Conf.
3-5 December 2004
Kyoto Japan
The generation mechanism of the Western Disturbances over the Himalayas
Hara, Masayuki (1), Kimura, Fujio (2), Yasunari, Tetsuzo (3)
(1) Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science Technology
(2) Institute of Life and Environmental Sciences, University of Tsukuba
(3) Hydrospheric Atmospheric Research Center (HyARC), Nagoya University
In winter, the western disturbances that generate and develop over the western area of the
Himalayas bring much snow in the central Himalayas (Lang and Barros, 2004). We analyzed
and simulated a typical case of the western disturbances using a regional meteorological
model. We also investegate the characteristics of the cyclone using an f-plane shallow water
equations model (SWEM). When a synoptic trough passed over the Tibetan plateau, the
southern part of the trough was cut off and a meso-alpha-scale quasi-stationary cyclone
formed aloft in the southwest of the Himalayas. Although the generated cyclone is almost
stationary and moves eastward very slowly, the remaining northern part of the trough moves
eastward faster than the subtropical westerlies. The southwestern moist winds at low level
flowed into the cyclone from the Arabian Sea and the Bay of Bengal. The southwestern winds
forced orographically and the upwind over the Himalayas caused snow along the southern of
the Himalayas. These properties also can be seen in the results of the SWEM simulations. The
vertical structure of the cyclone is barotropic and extends up to the tropopause. The phase
velocity and vertical/horizontal structure of the cyclone agree well with the theoretical
solution of the topographic Rossby wave in a stratified quasi-geostrophic fluid.
Submittal Information
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Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology | |
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3173-25 Showa-machi, Kanazawa-ku Yokohama Kanagawa 236-0001 | |
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hara.masayuki@jamstec.go.jp | |