Abstracts for the 6th International GAME Conf.
3-5 December 2004
Kyoto Japan
Transition of the precipitation process over the central Tibetan Plateau during the summer of 1998
YAMADA, Hiroyuki (1), UYEDA, Hiroshi (2)
(1) JAMSTEC-IORGC
(2) Hydrospheric Atmospheric Research Center (HyARC), Nagoya University
The precipitation process over the central Tibetan Plateau during the summer of 1998 was examined based on the data collected in the intensive field experiment of the GAME-Tibet project. The purpose of this study is to reveal the cause of the transition of summer rain, which increased after June in spite of the decrease in convective activity. All of rain events during the summer monsoon season were first separated into three types according to the synoptic-scale conditions, and a detailed analysis was then made for a type of rain event that showed remarkable intraseasonal change in daily amount of rainfall. The type of rain event focused upon here is related to a heat low that develops under the prevalence of a Tibetan upper high. The daily rainfall shows an obvious increase from 1.9 mm/day in June to 5.2 mm/day in August. An analysis using radar reflectivity showed that the increase was caused by convective rain in the daytime and stratiform rain at night. The convective rain increased, whereas convective activity decreased, due to the moistening of a sub-cloud layer that suppressed the evaporation of precipitation particles. Both the moistening of the ground and the activation of vegetation contributed to the moistening of air. This study thus suggest the importance of the ground conditions as a prevailing factor for the convective activity and precipitation process over the plateau in summer.
Submittal Information
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Institute of Observational Research for Global Change, Japan Agency for Marine-Earth Science and Technology (JAMSTEC-IORGC) | |
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3173-25 Shouwa-machi, Kanazawa-ku, Yokohama 236-0001 | |
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