春季印度洋SSTA对夏季中国西北东部极端降水事件的影响研究  

INFLUENCE STUDY ON SPRING INDIAN OCEAN SSTA TO SUMMER EXTREME PRECIPITATION EVENTS OVER THE EASTERN PART OF NORTHWEST CHINA

作　　者：江志红[1] 杨金虎[1,2] 张强[3] 

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 [2]中国气象局成都高原气象研究所,四川成都610071 [3]国家气候中心,北京100081

出　　处：《热带气象学报》2009年第6期641-648,共8页Journal of Tropical Meteorology

基　　金：国家重点基础研究发展计划项目(2006CB400504);国家科技支撑计划2007BAC29B03;高原气象科学研究基金项目LAP2007002共同资助

摘　　要：基于近47年来NCAR/NCEP再分析月平均高度场、风场、地面气压,比湿以及NOAA重构的印度洋海表温度资料和中国西北东部97个气象台站逐日降水资料,首先利用百分位法定义了极端降水事件的阈值,运用SVD及合成分析等方法,研究了前期秋季、冬季、春季及同期夏季印度洋海表温度同夏季中国西北东部极端降水事件的关系,结果表明前期春季印度洋海温异常对预测夏季中国西北东部极端降水事件的变化特征具有较明确的指示意义,关键区位于赤道印度洋地区。如果春季赤道印度洋海温异常偏暖,从同期春季到后期夏季,100～110°E平均经圈环流在赤道附近表现为异常上升气流,对应30°N附近在对流层中、上层表现为异常的下沉气流,同时来自印度洋的西南季风异常偏弱,使得后期夏季由于没有异常的水汽输送到我国西北东部地区,从而极端降水事件偏少,而偏冷年份正好相反。另外在春季赤道印度洋海温异常暖年,后期夏季南亚高压偏强,且呈西部型;而在异常冷年,南亚高压偏弱,且呈东部型,这可能是引起夏季中国西北东部极端降水事件变化的另一原因。Based on the monthly mean height fields of NCAR/NCEP reanalysis, wind fields, surface pressure, specific humidity, NOAA-reconstructed sea surface temperature （SST） of the Indian Ocean, and daily precipitation data of 97 meteorological stations over the eastern part of Northwest China in the past 47 years, the thresholds for extreme precipitation （EP） events are defined using the percentile method, singular vector decomposition and synthetic analysis methods. The relationship is studied between extreme EP events in the eastern part of Northwest China and SST in the preceding spring, winter, spring and the concurrent summer. The result shows that preceding spring SST anomalies （SSTA） in the Indian Ocean are clear indicators for the forecast of summer EP events in the eastern part of Northwest China, with the key areas located in the equatorial Indian Ocean. If spring SSTA is anomalously high in the equatorial Indian Ocean, the circulation averaged over 100 - 110 °E will be anomalously ascending near the equator and anomalously descending near 30 °N in the middle and upper troposphere. In the meantime, the Southwest Monsoon from the Indian Ocean will be anomously weak and there will be no anomalous transport of water vapor to the eastern part of Northwest China, resulting in the lack of summer EP events and the opposite is true when SST is anomalously low. In addition, in response to anomalously high spring SST in the equatorial Indian Ocean, the South Asia high tends to weaken in the consecutive summer and locates more to the west. In the anomalously cold year, however, the South Asia high tends to be weaker in the consecutive summer and locates more to the east. This is another reason why summer EP events vary in the eastern part of Northwest China.

关 键 词：气候学 极端降水事件 SVD SSTA 中国西北东部 印度洋 

分 类 号：P434.4[天文地球—大气科学及气象学]