青藏高原下垫面对中国夏季环流影响的研究

发展了一个CCM3－RegCM2单向嵌套模式，用以研究青藏高原中西部地区下垫面特征对我国夏季环流和降水的影响。结果表明：若青藏高原中西部植被破坏，变为沙漠，则该地区地面返照率增加，热容量减少，气温升高。从而导致高原北侧的温度梯度增大，西风槽则被削弱；西风急流被推至更西更北的地区，使得北方冷空气难以到达我国长江、黄河流域；由于高原上空气温增高，导致该地区上空的反气旋环流增强，使原来位于槽前西南气流的长江中下游地区处在平直西风气流当中，不利于降水的产生。与此同时，副热带高压西伸北抬，使得长江、黄河中下游地区处在副热同压控制之下，造成我国大部分地区夏季降水减少。

Influences of Surface Conditions over the Tibetan Pleateau on China Summer Circulation

By employing CCM3-RegCM2 nesting model which is developed on the base of NCAR CCM3 and RegCM2,the influences of surface conditions over the midwest Tibetan Plateau on summer precipitation in China are studied.The results show that the temperature gradient over the northern Plateau is strengthened as a result of surface albedo and temperature of the west-central Tibetan Plateau increasing if the vegetation over there are damaged,and the westerly jet should move to farther north and west to prevent the north cold air from reaching in the Yangtze River and the Huanghe River Basins so that the rainfall reduce in those areas,meanwhile,the anticyclonic circulation over the Tibetan Plateau which is enhanced by the increasing of air temperature would change the air stream direction from southwesterly into westerly in the Yangtze River.At the same time,subtropical high moves towards west and north and dominates the Yangtze River,leading to the summer precipitation decreasing in China.