影响华南西部的登陆热带气旋的若干气候特征

利用1950-1999年台风年鉴资料,结合广西89个测站的降水资料,统计和分析了登陆影响华南西部热带气旋的若干气候特征.结果表明,进入华南西部的热带气旋数占登陆华南沿海地区总数的75%;年均有1.9个热带风暴级别以上的热带气旋进入广西,其中强热带风暴强度以上的占84%.进入华南西部和登陆华南地区的热带气旋都具有显著的年际变化特征.不同月份、不同热带气旋登陆后的维持时间差异极大,平均维持时间的长短与登陆后12 h内强度的衰减程度密切相关.热带气旋引起暴雨的多寡和低压环流在广西境内的滞留时间成正相关,而与登陆时的强度没有明显的关系.

Climatic Features of Tropical Cyclones Invaded Southwestern China

In this study, the climatic features of the tropical cyclones ( TCs) affecting Southwestern China including Guangxi province is analyzed based on the data from the typhoon year-books (1950-1999). Statistical analyses show that TCs landfalling in western part in South China account for 75% of the total numbers of those making landfall in south-China. On the average, the numbers of TCs invaded Guangxi ( with their center positions located within Guangxi and the maximum sustained surface winds greater than 17 m/s - tropical storms ) are about 1.9 cases per year. And among them, those with maximum sustained surface winds greater than 24 m/s (severe tropical storms ) may account for 84% of the total. Both the number of TCs made landfall onto South China and the number of TCs entered into the south-western China show distinct annual variations. It is also found from the analyses that among those TCs having great impacts on Guangxi, the TCs of longest-duration time over land area after landfall occur in August, and the second longest duration ones are found in September. However, in Guangxi province, the longest duration TCs are observed in September. The duration time of landfalling TCs is quite different from case to case, depending on their intensity and weakening process within 12 hours after lanfall. The amount of heavy rain caused by the TCs is more closely related to the duration time of their low pressure cyclonic circulation within Guangxi province than their intensity at landfall.