江南春雨的两个阶段及其降水性质  

TWO STAGES OF SPRING PERSISTENT RAINS OVER SOUTHEASTERN CHINA AND THE NATURE OF PRECIPITATIONS

作　　者：刘宣飞[1] 袁旭[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,江苏南京210044

出　　处：《热带气象学报》2013年第1期99-105,共7页Journal of Tropical Meteorology

基　　金：江苏高校优秀学科建设工程项目(PAPD);国家自然科学基金重点项目(40633018)共同资助

摘　　要：根据1970—2009年平均的逐候NCEP/NCAR再分析资料和1979—2008年平均的逐候CMAP降水资料,分析了第1—27候江南地区(110～120°E,23～30°N)降水的阶段性特征。通过滑动t检验方法,发现江南地区的春季降水分别在第10、16候出现突增,达到99%的统计信度。为此,将第10候确定为江南春雨的建立日期,并将江南春雨期划分为两个阶段:第10—15候为第一阶段,第16—27候为第二阶段。伴随着江南春雨降水量的两次突增,青藏高原东南侧(105～112°E,20～25°N)的西南风也有两次突增,但时间要比江南春雨早1～2候。与第一阶段相比,第二阶段东亚经度上的冬季型Hadley环流消失,江南地区的上升运动向上扩展至200 hPa高度,纬向海平面气压场梯度由大陆高、海洋低的冬季型转为大陆低、海洋高的夏季型,大气层结不稳定性和对流性降水率均增加,这表明第二阶段的江南春雨已具有副热带季风降水的性质。Based on 1970--2009 NCEP/NCAR pentad reanalysis dataset and 1979--2008 CMAP pentad rainfall dataset, seasonal variation features of spring persistent rains （SPR） in Southeastern China （110～ 120°E, 23～30 °N） from the 1st to 27th pentad are investigated. By the technique of moving-t test it is revealed that SPR increases abruptly at the 10th and 16th pentads, reaching the 99% significance level. Therefore, the 10th pentad can be regarded as the onset date of SPR. SPR can be divided into two stages： the first from 10th to 15th pentad, and the second from 16th to 27th pentad. Accompanied with the abrupt increase in rainfall, there exists rapid enhancement in southwesterly in the southeastern flank of the Tibetan Plateau, which happens 1 - 2 pentads ahead of SPR. In its second stage of SPR, a winter-pattern Hadley cell along East Asia disappears, and the ascending motion can reach up to 200 hPa over Southeastern China, being associated with the eastward pressure gradients and high convective precipitation rates as well as convective instability, all indicating that the rainfall in its second stage of SPR is actually subtropical monsoon rainfall in nature.

关 键 词：气候学 江南春雨 副热带季风降水 降水性质 滑动t检验 

分 类 号：P461[天文地球—大气科学及气象学]