梅雨准双周振荡的年际变化及其前期强信号分析  

Analysis of the interannual variability of the Meiyu quasi-biweekly oscillation and its previous strong influence signal

作　　者：尹志聪[1,2] 王亚非[1] 袁东敏[3] 

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081 [2]北京市气象局,北京100089 [3]中国气象局华风气象影视集团,北京100081

出　　处：《大气科学学报》2011年第3期297-304,共8页Transactions of Atmospheric Sciences

基　　金：JICA中日政府间合作项目;国家科技部公益行业(气象)科研专项(GYHY201006009);中国气象科学研究院灾害性天气重点实验室2009自主研究项目(2009LASWZF04)

摘　　要：利用1954—2005年中国740站逐日降水资料和NCEP/NCAR再分析资料,分析了江淮梅雨准双周振荡的年际变化,并讨论了异常年的海气背景特征。将滤波后的每个降水周期划分为8个位相,其中第3位相对应准双周降水正距平最大,而第7位相对应准双周降水负距平最大,在此基础上的诊断结果表明:1)振荡强弱偏差场,在梅雨降水偏多的第3位相,低层大气中类似Rossby波列从南海经日本海、鄂霍次克海和阿留申群岛延伸至阿拉斯加地区,其中南海上空的反气旋和日本上空的气旋相互配合,造成冷暖空气在江淮地区交汇,有利于准双周降水正距平的产生。在降水偏少的第7位相,波列位相基本反向,传播路径偏南。2)第3位相时高层环流显示,鄂霍次克海地区高度场正异常明显,和我国东北地区的负距平共同作用为梅雨降水提供了足够的干冷空气。第7位相分布相反。3)前期3月至同期的黑潮及其延伸区海表温度和梅雨的准双周振荡强强度之间呈很好的正相关关系。黑潮及其延伸区持续的正海温异常,通过影响西太平洋副热带高压的位置和强度的变化,进而增强梅雨降水的准双周振荡。Based on the 740 stations’ daily rainfall datasets in China from 1954 to 2005 and the NCEP/NCAR reanalysis data,we analyzed interannual variability of the Meiyu quasi-biweekly oscillation over Yangtze-Huaihe River Valley and discussed the background features of atmosphere circulation and sea surface temperature in anomaly years.We divided each rainfall circle into 8 phases.Phase 3 corresponds to the largest positive rainfall,while phase 7 corresponds to the largest negative rainfall.The results are as follows：1） the differences between strong and weak oscillation years showed that during phase 3,there is a Rossby wave-like train extending from South China Sea to Alaska,via the Sea of Japan,Sea of Okhotsk and Aleutian Island in lower atmosphere.The anti-cyclone over South China Sea coordinated with cyclone over Japan is conducive to rainfall over Yangtze-Huaihe River Valley.While in Phase 7,the wave train is out-of-phase,and extends in a more southern path;2） in the higher level atmosphere,during phase 3,a significant positive anomaly of geopotential height occurred over Sea of Okhotsk.Together with the negative anomaly over Northeast China,the anomaly supplied adequate cold and dry air for the rainfall.3） The SST（sea surface temperature） of the Kuroshio and its extension zone from March to July showed a very significant positive correlation with the intensity of Meiyu quasi-biweekly oscillation.The lasting positive offshore SST anomaly strengthens Meiyu quasi-biweekly oscillation by regulating the position and intensity of the Western Pacific Subtropical High

关 键 词：梅雨 准双周振荡 低频振荡 近海海温 小波分析 

分 类 号：P426.614[天文地球—大气科学及气象学]