夏季青藏高原热力场和环流场的诊断分析 Ⅰ.盛夏高原西部地区的水汽状况

The Influence of the Tibetan Plateau on the Summer Thermal and Circulation Fields over East Asia I. The Humidity on the Western Tibetan Plateau in the Height of Summer

本文使用青藏高原气象科学实验测站观测资料、欧洲中心FGGE-Ⅲb资料、GMS1地球同步卫星云图资料、河流水文资料以及其他一些有关的资料,详细分析了1979年7月青藏高原地区,尤其是高原西部地区的水汽状况、水汽输入的通道,讨论了夏季青藏高原地区高湿状况的维持机制. 通过研究,发现在1979年盛夏青藏高原西部也是一个高水汽区域,有利于大量的湿对流系统活动,但西部比东南部的水汽含量要略低些;潜热加热是夏季高原西部重要的热源之一;除了过去已知的在高原东南和仲巴、定日一带的两条水汽通道外,水汽还可从高原西侧边界进入高原西部.在讨论夏季高原地区高湿状况的维持机制时发现,相对于高原东部,只需要较少的水汽输入就足以维持高原西部大气的高湿状态;高原西部的降水、蒸发和向土壤中渗透是接近于平衡的,水分循环主要是局地的内循环.

Based on the Tibetan Plateau Meteorology Experiments (TIMEX) data, the ECMWF FGGE Level IIIb data, the cloud atlas from the GMS1 earth synchronous satellite, the river hydrological data and some other relevant information, the moisture condition during the summer of 1979 on the Tibetan Plateau, especially on its western part, the moisture input channels, and the maintenance mechanism of the high humidity on this plateau in summer are detailed.To summarize, the main results of this study are summaried as follows.(a) There is a high humidity, which can be advantageous to enhance the activities of the frequent moisture convective activity systems, on the Western Tibetan Plateau in the height of summer 1979, so that the latent heat is one of the significant heat sources. But the humidity on the Western Tibetan Plateau is somewhat lower than those on its southeastern part.(b) Besides of the two known moisture input channels which locate in the Southeastern Tibetan Plateau and the Zhongba, Dingri area, water vapour can also be inputted into the Western Tibetan Plateau through its west boundary.(c) In comparison with those on the Eastern Tibetan Plateau, just small amount of water vapour is quite enough to maitain of the hgih humidity condition on the Eastern Tibetan Plateau.(d) In the water budget, the precipitation, the evaporation and the permeating of the soil are nearly balanced on the Western Tibetan Plateau, so that the water circle is a inner circle basically.