江南西部雨季降水区域特征及其受热带海洋海表温度异常的影响分析  

Study on Rainfall Characteristics in Rainy Season in Western Jiangnan Region and Its Possible Links with SSTA in Tropical Oceans

作　　者：吴贤云[1,2,3] 丁一汇[4] 叶成志 段丽洁[3] 王琪 

机构地区：[1]南京信息工程大学,南京210044 [2]中国气象科学研究院,北京100081 [3]湖南省气候中心,长沙410118 [4]国家气候中心,北京100081 [5]湖南省气象台,长沙410118 [6]湖南省气象公共服务中心,长沙410118

出　　处：《气象》2015年第3期286-295,共10页Meteorological Monthly

基　　金：国家自然科学基金项目(41130960);公益性行业(气象)科研专项(GYHY201406001和GYHY201306016);国家重点基础研究发展计划(973计划)(2012CB417205和2013CB430202)共同资助

摘　　要：本文分析了江南西部雨季特征,研究了热带太平洋、印度洋海表温度异常对这一区域雨季降水的影响,并初步分析了其影响因子。结果表明:(1)江南西部雨季开始时间早,持续时间长,是中国梅雨季的一个重要组成部分。它具有明显的年际、年代际变化特征,21世纪后,进入了一个少雨期。(2)前冬热带海洋海温异常是江南西部雨季降水丰枯的一个强信号。即:当赤道中东太平洋海温为正(负)距平、西太平洋及中东太平洋副热带地区为负(正)距平(这种海温异常主模态分别称为正(负)海温异常型),相应地,热带印度洋表现为北正(负)南负(正)的海温反相位型时,江南西部雨季全区降水偏多(少)的可能性大。(3)在正(负)海温异常年,4~6月,赤道印度洋盛行偏东(西)风异常,不易(容易)形成转向北的南风异常,印度季风弱(强);西太平洋近赤道地区为强劲的偏东(西)风异常,其北为反气旋(气旋)性距平环流,导致西太平洋副热带高压位置异常偏西(东),强度偏强(弱)状态,有利于(不利于)江南西部降水发生。(4)在正海温异常年,江南西部水汽主要来源于西太平洋,并在此区域形成水汽辐合,有利于降水;而在负海温异常年,来自两大洋的水汽均通过江南西部地区,此区域成为水汽过渡带,不易形成水汽辐合,降水偏少。By comparing the Western Jiangnan rainy season and the Meiyu season in Eastern China,preliminary analysis on what and how the tropical Pacific and Indian sea surface temperature anomaly(SSTA)affects the regional precipitation was performed,and then the potential mechanism was studied.The results showed that:(1) Western Jiangnan rainy season,which starts early and lasts for a longer period,is an important part of China Meiyu season.It has obvious interannual and interdecadal variations,of which,since the beginning of twenty-first century,it has been into a relative dry period.(2) The SSTA in the previous winter in tropical ocean is a strong signal for more or less rainfall in Western Jiangnan rainy season.That is,when SSTA in eastern equatorial Pacific is positive(negative),SSTA in West Pacific and the subtropical area of East Pacific is negative(positive),and SSTA in tropical India Ocean is positive(negative) in north and negative(positive) in south,there will be more(less) precipitation in Western Jiangnan Region in the following rainy season,which corresponds to more(less) rainfall in South and less(more) in North in China in Meiyu season.(3) In the positive(negative) tropical SSTA years,strong easterly(westerly) wind anomalies prevail in India Ocean,and they are difficult(easy) to turn north to become southerly anomalies,that is to say,the Indian monsoon is in a weak(strong) phase.At the same time,there are strong easterly(westerly) anomalies in West Pacific equatorial regions,and an(a) anticyclone(cyclone) anomaly circulation dominates the northern part of Pacific,which means the West Pacific subtropical high extends to westward(eastward),in a stronger(weaker) state.So,it is(not) beneficial to precipitation in Western Jiangnan.(4) In the positive tropical SSTA years,the water vapor source to Western Jiangnan comes mainly from the Western Pacific Ocean and forms net water vapor convergence in this area,conducive to more precipitation;but in the negative tropical SST abnormal years,the water vapor comes from bo

关 键 词：江南西部 雨季 海表温度 高空急流 SVD分析 

分 类 号：P461[天文地球—大气科学及气象学]