青藏高原对流云团东移发展的不稳定特征

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

  • 摘要: 利用1998年6~7月的逐时GMS红外TBB资料、T106的客观分析资料以及沿长江5个站的探空资料,对青藏高原上的对流云团东移维持发展的环流背景条件进行了分析。研究表明:高层气流辐散、低层气流辐合的垂直结构,高低空急流的引导作用,高原东南部和长江流域充沛的水汽条件以及大气层结的不稳定性是造成青藏高原上空对流云团东移的前提条件。

     

    Abstract: 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.

     

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