华南集中强降水的年代际变化及环流特征

本文利用中国气象局提供的华南65个站点的逐日观测以及NCEP再分析数据，对华南夏季降水的年代际转变及其集中强降水的环流特点进行了分析，主要结论如下：华南降水在1991/1992有明显的年代际变化，相关的大气环流场也发生了显著的转变。东亚上空的副热带西风急流减弱偏北，西北太平洋副热带高压位置偏西，华南上空低层辐合、高层辐散、垂直运动以及水汽输送的辐合也发生了明显变化。年代际上降水偏多时，西北太平洋和印度洋的水汽输送比平均情况更强。当集中强降水事件发生时，增加的水汽输送主要源于西北太平洋和中国南海。进一步分析表明1991/1992年之后印度洋的水汽输送增加，但是西北太平洋的水汽输送减少。这一发现很好的说明了自1991/1992年以来华南集中强降水事件的重要变化。

Interdecadal Change of Clustered Extreme Precipitation Events in South China and Atmospheric Circulations

By using 65 station daily precipitation data provided by the China Meteorological Administration and NCEP reanalysis data, this paper discussed the interdecadal change of the precipitation and the clustered extreme precipitation event in South China. Main conclusions are as follows: The precipitation in South China has experienced an obvious interdecadal change in 1991/1992, during this period, atmospheric circulation also shows a significant shift, including an intensity decrease and northward shift for the westerly jet over east Asia, an eastward shift for the northwest Pacific subtropical high, increases in the convergence at low level, the divergence at high level, the upward movement and the convergence for the water vapor transport. In addition, the water vapor transport associated with extreme precipitation is also different from the mean condition. During extreme precipitation events, water vapor transmission in the Indian Ocean and northwest Pacific is more than mean condition. In the case of heavy rainfall events, the increase of water vapor is mainly due to northwest Pacific and the south China sea. Further analysis indicated that water vapor transmission increased in the Indian Ocean after 1991/1992, while water vapor in the northwest Pacific decreased. This finding is a good illustration of the important changes in the concentration of precipitation in southern China since 1991/1992.