长江中下游地区冬季极端降水事件与天气尺度瞬变波活动的可能联系  

Relationship of Synoptic-Scale Transient Eddies and Extreme Winter Precipitation Events in the Middle and Lower Reaches of the Yangtze River

作　　者：陈海山[1,2] 朱月佳[1,2] 刘蕾[3] 

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室,南京210044 [2]南京信息工程大学大气科学学院,南京210044 [3]芜湖市气象局,芜湖241000

出　　处：《大气科学》2013年第4期801-814,共14页Chinese Journal of Atmospheric Sciences

基　　金：国家科技支撑计划课题2007BAC29B03;江苏省"333高层次人才培养工程";"青蓝工程"和江苏高校优势学科建设工程资助项目PAPD

摘　　要：利用ERA40、NCEP/NCAR逐日再分析资料和长江中下游地区85站逐日降水资料,从大气内部天气尺度瞬变波的角度对长江中下游地区极端降水事件进行了成因分析。研究发现瞬变波活动与极端降水的发生关系密切;冬季在两支急流并存的欧亚大陆上空存在南北两支瞬变波活跃带。南支瞬变波在冬季极端降水频发、少发年存在较明显的差异。总体而言,极端降水频发年,瞬变波活动活跃,欧亚大陆上空的瞬变波持续时间长、传播连续、强度偏强;极端降水少发年,则反之。从逐日变化来看,南支瞬变波的强度和能量传播过程与极端降水的发生频次均具有一定的对应关系。北支瞬变波的传播及瞬变波对水汽的输送和极端降水的发生也有一定促进作用。这些结果均表明,冬季极端降水的发生与天气尺度瞬变波的活动联系紧密,天气尺度瞬变波的异常活动及传播可能是极端降水发生的重要条件,研究可为极端降水的成因研究提供新的思路。The association of extreme winter precipitation events in the middle and lower reaches of the Yangtze River including synoptic-scale transient eddies is examined by using the ERA40 and National Centers for Environmental Prediction/National Center for Atmospheric Research （NCEP/NCAR） daily reanalysis data and daily rainfall data reported by 85 stations. A close relationship is detected between extreme precipitation events and transient eddies. In winter, two branches of synoptic-scale transient eddies are accompanied by subtropical and polar-front jets, respectively. It is demonstrated that the south branch of the transient eddies differs during highly and less frequent years of extreme precipitation events. Overall, transient eddies become active and strong, and they spread continuously with long durations over Eurasia during highly frequent extreme precipitation years; the reverse occurs for less frequent years. To some extent, the intensity and energy of the transient eddies both experience similar variations from the daily frequency of extreme precipitation. Moreover, the northern branch of the transient eddies and their water vapor transport are favorable for the occurrence of extreme precipitation events. Therefore, extreme winter precipitation events have a close relationship with the synoptic-scale transient eddy, implying the activity and propagation of transient eddies may be important factors in extreme precipitation events. This study is expected to provide a new perspective for the causes of extreme precipitation.

关 键 词：极端降水 瞬变波 天气尺度 长江中下游 

分 类 号：P433[天文地球—大气科学及气象学]