华南春旱特征及其与水汽输送的关系

利用1979-2005年华南47个基准站降水资料及由NCAR/NCEP II再分析资料计算所得的水汽输送通量资料,对华南春季降水特征及其与水汽输送的关系进行研究,结果表明:华南春季降水可以110.5°E为界划分为两个区域,以东区域为华南I区,以西区域为华南II区。I区降水具有显著的下降趋势,即干旱趋势显著;而II区降水下降趋势要弱得多,未超过信度检验。此外,I区降水在1994年发生突变,由多雨期突然跃变到干旱期。华南春季水汽主要来源于南海和西太平洋,并经中南半岛转向输送到华南,当南海中北部的偏南水汽输送偏弱(强)时,I区降水偏少(多),I区偏旱(涝),当南海西南部-中南半岛南部的偏南水汽输送偏弱(强)时,II区降水偏少(多),II区偏旱(涝)。

Characteristics of Droughts in Spring and its Relationship with Water Vapor Transportation in South China

By using the precipitation data of 47 basic stations in South China and the water vapor transport flux calculated from the NCAR/NCEP II reanalyzed data from 1979 to 2005,the characteristics of droughts in South China in spring and its relationship with water vapor transport flux are studied.The results show that precipitation in South China in spring can be partitioned into two classes.Region Ⅰ,located in the east of 110.5 °E,is characterized by the first class,showing an outstanding decreasing trend in rainfall.Region Ⅱ,located in the west of 110.5 °E ,is marked by the second class with unconspicuous decreasing tendency in reainfall.In 1994,there was an abrupt decrease in rainfall in region Ⅰ.The moisture source of South China is located in the South China Sea and western Pacific Ocean.The water vapor is transported to South China via the southern Indochina peninsula.When the southern water vapor transport is weaker/stronger over the central and northern South China Sea,the precipitation in region Ⅰ correspondingly becomes weaker or stronger and droughts or floods develop.While the southern moisture transport is weaker or stronger over the southwestern South China Sea and southern Indochina peninsula,droughts or floods prevail in region Ⅱ.