1969—2013年华南前汛期极端降水年际异常及影响因子

Extreme Precipitation During the Pre-rainy Season in South China,1969-2013:Interannual Variations and Influence Factors

利用国家气象信息中心发布的逐日降水资料、NCEP/NCAR逐月再分析风场及NOAA重构延长的逐月海表温度(SST)资料,研究了华南前汛期极端降水年际异常时空特征,并进一步从海洋及大气环流上探讨极端降水年际变化的主要影响因子。结果表明:(1)华南前汛期各极端降水指数呈显著年际变化特征,且在广东、广西、福建中北部和江西中南部呈一致性异常,贵州中南部呈相反异常分布。特别是1990s以来,广东、广西及福建中北部是洪涝灾害的高风险区,而贵州中南部则易发生干旱。(2)"类ENSO"型海温异常及相应大气环流异常是影响华南前汛期极端降水的主要因子,前冬到次年前汛期,"类ENSO"型正异常维持但有一定程度减弱,南海以北的东亚大陆沿岸自南向北依次存在反气旋—气旋—反气旋环流系统,南海及菲律宾群岛以东洋面的反气旋环流系统向北输送暖湿气流,贝加尔湖以东的反气旋环流和日本群岛附近的气旋式环流分别向南输送干冷和湿冷气流,南北气流交汇于华南地区,易造成华南前汛期洪涝灾害。

Using the daily precipitation data of 89 stations in south China from the National Meteorological Information Center and the reanalyzed monthly average 850 hPa wind field from the National Center for Environmental Prediction and the National Center for atmospheric research,as well as extended reconstructionmonthly sea surface temperature （SST） data from National Oceanic and Atmospheric Administration between 1969 and 2013,the authors studied the spatial-temporal features and influence factors of extreme precipitation during the pre-rainy season in south China from the perspective of ocean and atmospheric circulation.The results showed that：（1） the interannual variations of extreme precipitation during the pre-rainy season in south China were significant,most areas in south China were consistent anomaly,except for the central and south of Guizhou;since the 1990s,high flood risk areas were Guangdong,Guangxi and the north and central of Fujian,while the central and south Guizhou were prone to aridification;（2） the main affecting factors of the interannual variations of extreme precipitation in south China were ENSO-like sea surface temperature anomaly （SSTA）and the corresponding atmospheric circulation anomaly;ENSO-like SSTA had a certain degree of decrease from the preceding winter to the pre-rainy season,east Asian continent along the coast had the anti-cyclone-cyclone-anticyclone system from south to north,the anticyclonic circulation system of the south China sea and east ocean of the Philippines conveyed the warm moist air flows to the north,the anticyclonic circulation in the east of Lake Baikal and the cyclonic circulation near the Japanese islands conveyed the wet dry and cold air southward,respectively,which increased the warm and humid vapor input to south China and caused extreme floods in pre-rainy season in south China,and vice versa.