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)

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

Name : Date :
    Hara, Masayuki
    09-Aug-04-14:51:34
Organization : Theme :
    Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology
    Theme 4
Address : Presentation :
    3173-25 Showa-machi, Kanazawa-ku Yokohama Kanagawa 236-0001
    Poster or oral
Country : Abstract ID :
    Japan
    T4HM09Aug04145134
Phone : Fax :
    +81-45-778-5545
    +81-45-778-5706
E-mail :
    hara.masayuki@jamstec.go.jp