2003年夏季我国南方大旱天气学背景分析

利用NCEP／NCAR再分析资料和我国南方25个测站逐日降水量资料，分析了2003年我国南方夏季降水异常与春季、夏季高空环流场和温度场异常的关系。结果表明，2003年夏季西太平洋副高异常偏西、偏北，控制了长江以南大部分地区，这是造成夏季少雨的主要原因。夏季南亚高压异常强大东伸，对西太平洋副高的西伸加强起着一个动力引导作用。西太平洋副高与南亚高压重叠区域对应主要干旱区域。此外，我国南方夏季降水与100hPa温度场存在1～2个月滞后相关美系．前期欧亚大陆中高纬地区100hPa温度场异常可以作为长江以南地区旱涝的预报因平．

Synoptic Analysis of Severe Droughts during the Summer 2003 in Southern China

Based on NCEP/NCAR reanalysis data and the daily precipitation of 25 stations in southern China, the relationship between the anomalies of the summer precipitation in southern China and the upper level geopotential height and temperature anomalies in the spring and summer 2003 was analyzed. Results show that the Subtropical Anticyclone over the Western Pacific during the summer 2003 shifted southward and northward, and controled the most part of the southern China, which resulted generally in the meager rainfall in the area during the summer. The South Asian High in the summer 2003 was much stronger than normal and extended eastward, dynamically inducing the westward extension of the Subtropical Anticyclone over the Western Pacific. The overlay area of the South Asian High and the Subtropical Anticyclone corresponds primarily to the area with drought. In addition, the summer precipitation in southern China correlated significantly with the temperature at 100 hPa with a lag of 1-2 months. The previous temperature anomalies at 100 hPa in middle and high latitudes may serve as an important predictor for the drought and flood in southern China.