2012年夏季我国降水异常及成因分析

Analysis of Rainfall Anomalies in China in Summer 2012

2012年夏季我国降水呈现雨带位置偏北,雨量偏多的异常特征。进一步对2012年夏季我国北方地区降水异常偏多成因分析表明,2012年夏季东亚夏季风显著偏强,副热带高压脊线位置偏北,将大量的暖湿水汽持续向我国北方地区输送,而欧亚中高纬大气多短波槽活动,短波槽带来的冷空气和来自南方的暖湿空气频繁在我国北方地区汇合,造成我国北方地区降水异常偏多。此外,前期拉尼娜事件和太平洋PDO冷位相是造成我国北方降水异常偏多的重要外强迫条件。

The average precipitations were more than normal in northern China in summer 2012. The cau- ses of precipitation anomalies were analyzed. Results showed that more warm and humid water vapor was transported continuously to northern China due to the stronger East Asian summer monsoon and the north- ward West Pacific subtropical high ridge. While shortwave troughs were in activities in the mid-high lati- tudes over the Eurasia in summer 2012, they brought about more cold airs, and the latter converged with the warm and humid airs from the South China Sea and the East China Sea in northern China, which con- t, ,buted to the more precipitation above normal in northern China. In addition, early La Nina event and the PDO cold phase were the external forcing conditions to the precipitation anomalies in northern China.