THE WIND STRUCTURE AND HEAT BALANCE IN THE LOWER TROPOSPHERE OVER TIBETAN PLATEAU AND ITS SURROUNDING

First in this paper the mean 2-year mean winter and summer wind fields below 6 km over Tibetan Plateau and its surrounding are presented.In winter the main features on 1.5 km (fig.1)and 3 km (fig.2)level are the splittzing of the westlies over the plateau,the line of convergence to the east of the plateau and the "dead-water" regions (characteri2ed by calm wind and little disturbances,except small local vortices) respectively to the east and west of the plateau.On 6 km,(fig.4) the minor features disappear but the splitting is still evident.In summer in the vicinity of the,plateau low level wind blows cyclonically around it (fig.6-7).Surround this,large cyclonic whirl are small systems.On 6 km (fig.8) the wind blows anticyclonically around the plateau.The center of the this anticyclone may be located at the SE corner of the plateau.This kind of vertical structure of this wind field indicates that the temperature over the,plateau is higher than the surrounding.The region of high temperature is estimated to reach at least as high as 9 km.There is strong vertical motion in the vicinity of the plateau.In winter on its SE the motion is upward,while in the rest of the region the motion is in the main downward.In summer the mean motion fundamentally upward velocity reaches about 1 cm/sec,on 6 km.Mean advection and temperature gradient (fig.5 for winter and fig.9 for summer) between 3-6 km are also calculated from the wind data under geostrophic assumption.Secondly the heat balance over the ulateau is estimated from the calculation of short wave absolpnon,cenoensauon nearing,long wave coonng,temperature anvecuon,aoianaoc coonng (or warming) due to vertical motion and turbulent heat transfer from the grounad.From this calculation it is concluded that Tibetan Plateau is a heat source in summer,while in winter the result is not very conclusive.Probably in winter the SE part of it plays a role of warm source while the rest of the plateau plays a role of cold source.