江淮流域夏季持续性强降水的低频特征分析  

Low-frequency oscillations of persistent heavy rainfall over Yangtze-Huaihe River Basin

作　　者：曹鑫[1,2] 任雪娟[2] 孙旭光[2] 

机构地区：[1]中国民用航空青岛空中交通管理站气象台,山东青岛266108 [2]南京大学大气科学学院,南京210093

出　　处：《气象科学》2013年第4期362-370,共9页Journal of the Meteorological Sciences

基　　金：国家重点基础研究发展计划(973计划)项目(2012CB417203);公益性行业(气象)科研专项(GYHY201106017);国家科技支撑计划项目(2009BAC51B01);江苏高校优势学科建设工程资助项目

摘　　要：利用1979-2009年夏季（6-8月）中国气象观测站点逐日降水资料、NCEP／NCAR的再分析资料以及向外长波辐射资料等，选取低频降水事件来表征江淮流域夏季持续性强降水，然后分析其基本特征及伴随的低频大气环流形势，利用位相合成的方法对该低频信号的来源和传播特征进行研究。结果表明：江淮流域夏季持续性强降水在6-7月份发生次数较多；在持续性强降水期间，江淮流域低层受低频气旋控制，南海至菲律宾海一带则是很强的低频反气旋，该低频反气旋西侧，向北的低频水汽输送将水汽不断送至江淮流域形成辐合；与持续性强降水相关联的850hPa上的低频信号，来源于黄河河套地区低频振荡的东南向传播和西北太平洋上空低频振荡的西北向传播；在高层，当持续性强降水发生时，江淮流域的西北侧（37．5°N，80-100°E）附近为强烈的低频气旋式环流，紧邻该环流的西北侧，则是一个低频反气旋，两者同南海一菲律宾海一带的低频反气旋构成了一个西北一东南向的低频波列；西太平洋副热带高压和南亚高压在持续性强降水期间表现出了显著的相向而行、相背而去的特征。Using daily rainfall data in China, outgoing long wave radiation（OLR） data and NCEP/ NCAR reanalysis dataset from June to August during 1979--2009, this paper first characterizes summer persistent heavy rain over Yangtze-Huaihe River Basin （YHB） through selecting rain events of low fre- quency, then analyzes its low frequency oscillation and accompanied low frequency circulation condition. The source and propagation of the low-frequency signals are also investigated by phase-composite method. Results show that the summer persistent heavy rain over YHB occurs frequently in June and July. Accom- panied with the persistent heavy rain, a low frequency cyclone influences the YHB while a strong low fre- quency anticyclone affects region from the South China Sea （SCS） to Philippines Sea （PS） in the lower troposphere. The water vapor transportation in the west of the low frequency anticyclone brings water va- por to YHB. Both the southeast propagation of low frequency oscillation over the loop of Yellow River andthe northwest one over the northwestern Pacific at 850 hPa are two dominant signals of low frequency cir- culation associated with persistent heavy rain. In the upper troposphere, when the persistent heavy rain occurs a strong low frequency cyclone locates over the northwest of YHB centered around 80 -100°E, 37.5°N, close to which a low frequency anticyclone appeas. Thus, a low frequency wave train is formed from northwest China to the SCS and PS region. Before the peak of persistent heavy rain, the western Pa- cific subtropical high and the south Asia high begin to approach each other, then they tend to departure each other gradually after the peak.

关 键 词：持续性强降水 低频振荡 大气环流 

分 类 号：P461[天文地球—大气科学及气象学]