By using radiosonde data in Sichuan Province and Chongqing Municipality of China during May-September from 1982 to 2002, the meteorological significance and evolution patterns of the atmospheric boundary layer (ABL) wind on the eastern edge of the Tibetan Plateau are analyzed. Results show that the ABL wind at Chengdu near the eastern edge of the Tibetan Plateau varies with regularity. Because of the interaction between the circulation and the topography, the wind field alternates between northeast and southwest winds. When northeast ABL winds prevail at Chengdu, the ABL in the Sichuan Basin maintains a cyclonic flow field and corresponds with heavy rain in the Sichuan Basin. When southwest winds prevail, the ABL maintains an anticyclonic flow field and corresponds with rainless, fine weather in Sichuan Basin. With the northeast-southwest-trending topography between the Tibetan Plateau and the Sichuan Basin, the dynamic trigger of the ABL at Chengdu is a very important cause of occurrence and development of severe, convective weather and heavy rain in the Sichuan Basin. The Chengdu station is the key weather station in the Sichuan Basin for weather prediction and understanding physical mechanisms.
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