1998年夏季西南低涡活动与长江上游暴雨

Relationship between Abnormal Activites of Southwest Vortex and Heavy Rain the Upper Reach of Yangtze River during Summer of 1998

应用天气学和统计学方法,分析了1998年盛夏西南低涡活动的主要特征,指出该年夏季西南低涡活动偏强,该年长江上游暴雨偏多与此有关。

Using synoptic and statistical method, active characteristics of southwest vortex during summer 1998 is analyzed. The relationship between abnormal activities of southwest vortex and heavy rain in the upper reach of Yangtze River is research. The results are as follows: (1) There were 21 cases of southwest vortex in the upper reaches of Yangtze River during the summer of 1998. The development and movement kinds of vortices making up 71 percent of the all cases in the summer of 1998 are obviously more than the other years. (2) The abnormality of atmospheric circulation over the east part of Asia in 1998 was contributive to the development and movement of the SW\|vortices. (3) The unbalanced force and strong convergence of lower atmospheric motion in the activity area of SW\|vortices lead to its development as well as occurring heavy rain.