The Large-Scale Circulation and Heat Sources over the Tibetan Plateau and Surrounding Areas during the Early Summer of 1979. Part I: Precipitation and Kinematic Analyses

Abstract The time evolution of the large-scale precipitation, low-level (850 mb) wind, moisture and vertical motion fields over the Tibetan Plateau and surrounding areas during a 40-day period from late May to early July 1979 is studied based on the objectively analyzed FGGE Level II-b data set. During this period the general circulation over East Asia undergoes a distinct change characterizing the onset of the summer monsoon circulation. The Tibetan Plateau exerts profound orographic and thermal influences upon the low-level wind field. The inflow towards the eastern part of the Plateau with a marked diurnal change in its intensity is the most prominent feature of the low-level wind field. The areas of organized precipitation are well related to synoptic systems seen in the 850 mb flow: the quasi-stationary Burma-India trough, the disturbances forming on the trough, the “Mei-yu (Baiu)” front, and the “transverse trough” extending eastward from the Plateau. There is a sharp contrast between the western an...