热带环流系统异常对2003年淮河持续性暴雨的影响

THE INFLUENCE OF ABNORMITY OF TROPICAL CIRCULATION SYSTEMSON SUSTAINED RAINSTORMS IN HUAIHE BASIN IN 2003

利用高低层环流场及热带季风特征指数研究热带环流系统异常对2003年6～7月淮河持续性暴雨的影响。分析表明:来自南半球的越赤道气流向北半球推进的过程与大暴雨过程紧密联系;淮河流域上空高、低层异常偏强的辐散、辐合环流,为黄河与长江之间降水异常偏多提供了有利的高、低层环流条件;2003年南海夏季风爆发日期较常年偏晚,热带夏季风及环流强度较常年稍偏弱,它的逐月变化相似于1991年,是2003年淮河流域持续多雨的热带环流成因。

In this article we analyze the influences of the abnormity of tropical circulation systems on sustained rainstorm in the Huaihe River basin in June and July of 2003 by using the stream filed in the high and low levels and the index of tropical monsoon. The analysis shows that: the rainstorm has close relationship with northward advancing airflow from the Southern Hemisphere; it was the abnormal strong divergent and convergent air current in the upper and lower levels that offered available conditions to the abnormal rainfall between the Yellow River and the Yangtze River; the outbreak date of South China Sea Summer Monsoon in 2003 was later than normal and the tropical monsoon was weaker than normal, its monthly change was like 1991, and this is the circulation factor for the rainfall to sustain in the Huaihe River basin.