INSTABILITY OF EASTWARD MOVEMENT AND DEVELOPMENT OF CONVECTIVE CLOUD CLUSTERS OVER TIBETAN PLATEAU

The eastward movement and development of convective systems over the Tibetan Plateau are investigated with GMS infrared Black-Body Temperature (TBB), T106 reanalysis data and 5 station's sounding data along the Yangtze River basin in 1998. Results show that the processes of heavy rainfall along the Yangtze River basin coincide with the periods of low TBB. The convective cloud clusters display a substantial moving trend from the plateau to the mid and lower reaches of Yangtze River basin. The necessary conditions for heavy rainfall over the Yangtze River basin are the continuous accumulation of clusters at Sichuan and the merging itself with the cloud clusters in the Yangtze River basin and cloud clusters moving from plateau. It is also presented that the vertical structure of circulation, steering effects of high (low) jets, plentiful water over the southeastern plateau and the Yangtze River basin and the instability in troposphere are all favorable to the eastward movement and development of cloud clusters.