我国近海热带气旋强度突变的气候特征分析

ANALYSES OF CLIMATIC CHARACTERISTICS ACCOMPANYING SUDDEN INTENSITY CHANGES IN OFFSHORE TROPICAL CYCLONES IN CHINA

按国家气象局“八五”攻关办专家组提出的有关近海热带气旋强度突变的标准，对１９７０—１９９１年在我国近海发生强度突变的热带气旋进行了分类统计，发现如下气候特征：平均每年有８—９个热带气旋移到我国近海时发生强度突变，其中突然减弱的居多，占总个数的７９．６％，突然增强的只占总个数的２０．４％，突然增强只发生在５—１０月，而突然减弱则５－１２月均可发生；突然增强主要出现在浙闽沿海、南海中部、珠江口外西侧到北部湾北部的粤桂南部沿海及巴士海峡东侧，３０°Ｎ以北、１２５°Ｅ以西的华东沿海和南海东北部未见到热带气旋的突然增强，而突然减弱则海域分布较广。

Following criteria of sudden intensity changes in offshore tropical cyclones proposed by the experts of key projects office for the'8th five-year plan'in the national bureau,elassification statistics is done for the tropical cyclones in offshore Chinese waters 1970 through 1991 which meet the requirement.They all have the following climatic characteristics.There are in average 8-9 tropical cyclones per year whose intensity change abruptly as they move towards the offshore,among which 79.6% of the total weaken May through December while 20.4% intensity May through October;the former appears over vast area,while the latter is monthly seen over waters offshore the Zhejiang and Fujian Provinces,the central South China Sea,waters from the Pearl River Mouth across the Beibuwan Bay,and eastern Bashi Channel;No tropical cyclones enchance north of 30°N and west of 125°E or in the eastern South China Sea.