青藏高原地面辐射对中国东部夏季降水影响的数值试验

Numerical experiment of the influence of ground radiation over the Qinghai-Tibet Plateau on summer precipitation in eastern China

利用CAM5模式设计敏感性试验,研究了中国东部夏季降水对青藏高原地面辐射异常变化的响应和可能的物理机制。试验结果表明:当高原北部、中部等区域夏季地面辐射减小,中国东部夏季降水整体上增多,但南部、东部沿海区域降水异常减少。青藏高原地面辐射的变化,对青藏高压、西太平洋副热带高压和季风等天气系统具有一定影响,进而影响中国东部地区的夏季降水。当青藏高原地面辐射减小,青藏高压中心位置偏西,强度减弱;东亚季风和南亚季风强度增大,中国东部大部分地区850hPa风场强度增强;西太平洋副热带高压位置偏东,强度减弱,中国南部、东部沿海区域夏季降水受其影响而减少,但华中、华北、东北等地夏季降水整体上增多。故中国东部夏季降水异常变化与青藏高原地面辐射之间具有显著的相关关系。

Using CAM5 model,a sensitivity test has been designed to study the response of summer precipitation in eastern China to ground radiation anomalies over the Qinghai-Tibet Plateau and possible physical mechanisms. The results show that when the ground radiation weakens in the northern and middle Qinghai-Tibet Plateau,the overall summer precipitation in eastern China would be increasing,but precipitation in the southern and eastern coastal areas would be decreasing. The change of ground radiation over the Qinghai-Tibet Plateau and the South Asia High,Western Pacific subtropical high,monsoon has significant correlation,and has a close relationship with the summer precipitation in eastern China. When the ground radiation over Qinghai-Tibet Plateau decreases,the center position of the South Asia High is relative to the west and the intensity is relatively weak. At the same time the South Asian summer monsoon and East Asian summer monsoon intensities increase,and the 850 hPa wind field intensity is relatively strong. Besides,the Western Pacific subtropical high is relatively weak and its center position is relative to the east. And then summer precipitation decreases in the southern and eastern coastal areas of China,but precipitation in most parts of eastern China increases in summer. The anomaly of summer rainfall in eastern China has a significant correlation with the ground radiation over the Qinghai-Tibet Plateau.