西北干旱区感热异常对中国夏季降水影响的模拟

Numerical Simulation of the Impact of Abnormity of Sensible Heat Flux in Northwest Arid Zone on Precipitation in China

利用最新版的RegCM3模式通过增加西北干旱区地面向大气的感热输送,模拟了西北干旱区春、夏季感热异常对中国夏季降水的影响。结果表明:西北地区地面向大气的感热输送增加后,西北干旱区低层空气温度升高,空气密度减小使得空气有上升运动距平,减弱了空气的下沉运动,从而在新疆地区降水增加。西北地区下沉气流减弱使得高空气压更强,形成反气旋气流距平,导致高原地区上升气流减弱,在青藏高原降水减少。高原地区上升气流减弱导致在长江中下游和东北北部分别有负的气压距平中心,使得这里有气旋式距平环流,降水增加;而在华南、西南、华北南部和东北南部降水减少。

The impact of abnormity of sensible heat flux from surface to atmosphere in spring and summer in Northwest arid zone on precipitation in China in summer has been simulated by using RegCM3 model of the up to date edition,the results showed that,after the sensible heat in Northwest arid zone has been increased,the temperature in low layer will rise,and the air density will decrease so that there has an anomaly of ascending motion in Northwest arid zone.The sinking motion is weaken in Northwest arid zone,which will lead to more precipitation in Xinjiang.The weak sinking motion in Northwest arid zone make that there has a stronger air pressure in high layer,so there has a anomaly of anticyclonic circulation,which leads to the weaken ascending motion and the precipitation decreases in Tibetan Plateau.And then it makes a center of anomaly of low air pressure in the mid-and low-reaches of Yangtze River and the north of Northeast China,so that there have anomaly of anticyclonic circulation and more precipitation.However,The precipitation is less in South China,Southwest China,southern of North China and Northeast China.