2004年夏季经向型雨带及其与印度洋偶极模异常海温的关系  

The Meridian Pattern of Summer Rainfall in 2004 and Its Relationship with Indian Ocean Dipole

作　　者：肖子牛[1] 梁红丽 

机构地区：[1]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室 [2]云南省曲靖市气象局,曲靖655000

出　　处：《大气科学》2006年第5期791-801,共11页Chinese Journal of Atmospheric Sciences

基　　金：云南基金课题2003D0085M;国家自然科学基金资助项目D050740233033

摘　　要：针对2004年夏季降水为南北向雨带分布的异常特点，利用NCEP／NCAR再分析资料对可能造成2004年准经向降水分布的海温场、高度场及水汽输送特征进行了分析，并与夏季降水呈纬向分布的2003年进行了比对。分析结果表明，2004年夏季西太平洋副热带高压偏北、偏东，中国大陆中纬度地区东部为异常偏东水汽输送，西部为异常偏西的水汽输送，东、西风在110°E形成南北向交界，有利于形成南北经向型的水汽辐合和降水分布。而在2003年夏季，西太平洋副热带高压偏南、偏西，在长江以南形成稳定的带状副高，有利于雨带长时间稳定在副高北侧的淮河流域，同时中国大陆35°N以南地区为异常偏西水汽输送，以北地区为异常偏东的水汽输送，正、负异常纬向风形成东西向交界，有利于形成东西纬向型的水汽辐合和带状降水分布。对海温状况的分析发现，虽然2003年和2004年太平洋异常海温信号较弱，但印度洋和中国大陆近海海温却有明显的差异，2004年夏季西北太平洋异常海温北高南低，西印度洋海温异常偏冷，赤道热带印度洋海温呈东暖西冷的偶极模负相位特征。而在2003年淮河强降水发生同期，西北太平洋异常海温南高北低，西印度洋海温异常偏暖，赤道热带印度洋海温呈东冷西暖的偶极模正相位特征。因此，印度洋异常海温偶极模的不同相位可能是造成2003、2004年中国夏季降水不同雨带分布型的重要原因。利用中国160个代表站1950-1999的降水资料，进一步分析了印度洋偶极模不同相位异常海温对中国夏季降水的影响，结果发现，印度洋偶极模正相位有利于中国南方降水的西移和北方降水的东进，趋向于形成东西纬向型降水分布；而印度洋偶极模负相位有利于中国南方降水的东退和北方降水的西移，趋向于形成南北经向型降水分布。To the question of meridian pattern characteristic of 2004 summer rainfall, the characteristics of sea surface temperature anomalies （SSTA）, geopotential height and moisture transportation are studied by data analysis. The comparison with those in 2003, when the summer rainfall appears with a characteristic of zonal patterns, is made as well. The analysis shows obvious differences between 2003 and 2004 in summer. During the summer 2004, the location of the Pacific subtropical high is more north and east. There are positively anomalous zonal wind over western China but negatively anomalous zonal wind over eastern China in middle latitude regions. East wind meet west wind around 110°E, which is advantageous to form south-north meridian moisture convergence and precipitation pattern But in summer 2003, the location of Pacific subtropical high is more south and west. The subtropical high poses a zonal shape to the south of the Yangtze River, which benefits to maintain a precipitation zone over the Huaihe River basin. At the same time, there are positively anomalous zonal wind over southern China but negatively anomalous zonal wind over northern China. The dividing line between east wind and west wind is around 35°N, which is in favor of forming a zonal moisture convergence and precipitation pattern. Though the Pacific SSTA signals are weak in 2003 and 2004, there are obvious differences between the Indian Ocean and the seas near the China mainland. The Indian Ocean Dipole is in negative phase in summer 2004 but in positive phase in summer 2003. Based on the 160 stations observation data, it is revealed that the different phase of the Indian Ocean Dipole is closely related to the summer rainfall patterns over China. The positive phase of the Indian Ocean Dipole will increase precipitation in southwest but decrease in northwest in China. It seems advantageous to form an east-west zonal summer rainfall pattern. Otherwise, the negative phase of the Indian Ocean Dipole will decrease precipitation in southwest but in

关 键 词：雨带分布型 印度洋偶极模 异常海温 水汽输送 

分 类 号：P461[天文地球—大气科学及气象学]