Abstracts for the 5th International GAME Conf.

3-5 October 2001

Aichi Trade Center

Nagoya Japan

Effects of the temporal variations of air temperature and westerly jet over the Tibetan Plateau on the Somari-Jet Formation

Kenji Taniguchi (1), Toshio Koike (2)

Our understanding of the Asian summer monsoon mechanisms should be improved to contribute to more effective water resources and weather predictability. There are still many ambiguities in the seasonal march of the Asian summer monsoon even the monsoon system has been studied for long. This study focuses on the Somari-Jet formation by seeking its relationship with meteorological conditions over the Tibetan Plateau based on the satellite- and model-derived datasets. The seasonal march of the wind field at 850hPa over the Eurasian continent and the Indian Ocean in 1991 and 1992 was investigated by relating with the meteorological parameters. The datasets used in this study were provided by NCEP/NCAR reanalysis project and the Satellites Data Utilization Office (NASA Goddard Space Flight Center). The Somari-Jet formation, which is considered as the start stage of the monsoon as many studies have already pointed out, is controlled by following possible three processes: a) a decay of the westerly jet over the Tibetan Plateau, b) a thermal contrast between the air masses over the Tibetan Plateau and the Indian Ocean, c) a thermal contrast between the air masses over the Arabian Peninsula and the Indian Ocean. The inter-comparison between the wind and the air temperature fields in 1991 and 1992 shows the air temperature increase over the Tibetan Plateau antecedent to the Somari-Jet formation and the negative correlation between the westerly jet and the air temperature over the Tibetan Plateau. These two relationships suggest the following possible processes of the seasonal march of the Asian summer monsoon: 1) the westerly jet decay over the Tibetan Plateau, 2) the air temperature increase over the Tibetan Plateau due to decrease of advection as a result of 1), and 3) the Somari-Jet formation due to the thermal contrast increase between the air masses over the plateau and the Indian Ocean.

Submittal Information

Name : Date :
    Mr. Kenji Taniguchi
    30-May-01-17:15:47
Organization : Theme :
    Department of Civil Engineering, Univresity of Tokyo
    Theme 5
Address : Presentation :
    7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
    Poster or oral
Country : Abstract ID :
    Japan
    T5MKT30May01171547
Phone : Fax :
    +81-(0)3-5841-6108
    +81-(0)3-5841-6130
E-mail :
    taniguti@hydra.t.u-tokyo.ac.jp