浙中地区前汛期降水异常的大气环流响应

The Linkages Between The Annually First Raining Period Precipitation in The Middle Part of Zhejiang and The Circulation Anomalies

利用1953-2008年NCEP/NCAR日平均再分析资料、大气环流指数资料、浙中地区逐日降水资料,采用合成分析方法对浙中前汛期(5～7月上旬)降水异常的大气环流特征进行了分析。结果表明:降水偏多年南压高压强度较常年偏弱,高层气流辐散偏强,副热带高压强度偏强,西伸脊点明显偏西,纬向环流偏弱,经向环流偏强,印度西南季风和副热带季风偏强,冷暖空气交汇于长江中下游,造成浙中前汛期降水偏多;降水偏少年则恰好相反,南压高压偏强,高层辐散度偏弱,副高强度略偏弱,西伸脊点偏东,纬向环流偏强,印度西南季风和西南夏季风偏弱,北部冷空气偏强,南部暖空气偏弱,暖湿气流北上受阻,造成少雨。

Based on daily mean ncep reanalysis data and the circulation index data and daily precipitation data in the middle part of zhejiang,using synthesize analysis method,the linkages between the annually first raining period precipitation in the middle part of zhejiang and the circulation anomalies is analyzed,the result is that：in the more precipitation years, the intensity of south asia high is less than the mean intensity of that, but plus divergence of upper air is larger than mean intensity. The intensity of horse latitude higt is larger,and the west ridge point is more west, zonal circulation is less, and meridional circulation is larger, Indian monsoon and subtropical monsoon are larger, cold air and warm air converge in middle and lower reaches of the Changjiang River, so those work precipitation of middle part of zhejiang more. In the less precipitation years,that is reverse.