1998年5～6月区域大气角动量收支与东亚天气尺度系统变化

Relationship between Variability of the Regional AAM Torque and Synoptic Scale System over East Asia in May and June 1998

利用NCEP/NCAR再分析资料计算了1998年5～6月区域角动量收支的主要分量,对比分析了范围较大的欧亚区域角动量矩和限制在欧亚大陆范围内的喜马拉雅山角动量矩的差异,发现两者有很好的相关,限制较小范围的计算表明,喜马拉雅山山脉力矩的作用显著。角动量收支项占较大量级的山脉力矩和摩擦力矩,并与梅雨锋区域的700hPa高度进行了滞后相关分析,发现摩擦力矩与梅雨区域700hPa高度场有提前3天的较高相关,它们的滞后相关存在6天左右的周期。合成分析表明,较大的负山脉力矩对应着可降水量的正距平带,该距平带从长江以南区域延伸至日本以南区域;较大的负摩擦力矩出现后3天对应着可降水量的更大正距平,且覆盖江淮区域延伸至日本南部区域。

Using the reanalysis data,the main torques of atmospheric angular momentum（AAM） in May and June 1998 were calculated.Firstly,comparing with the difference between Eurasian and Himalaya torques,it is found that the torques between the two regions are well correlated and the one in smaller area well focuses on Himalaya Mountain.There was significant positive correlation between 700 hPa height field in Meiyu frontal zone and the regional friction torque which leads the 700 hPa before 3 days.Their lag correlations show a 6-day period.Finally,the composited analysis shows that the larger negative Himalaya mountain torque was associated with positive precipitable water anomaly belt from the area south of the Yangtze River to the sea area off the south coast of Japan while larger negative regional friction torque in preceding 3 days was associated with larger positive precipitable water anomaly covering from Jiangsu Province and Huaihe river to the South Japan.