影响长江口区热带气旋的特征分析

Characteristic Analysis of Tropic Cyclone on Changjiang Estuary

根据1979-2002年大戢山和引水船的观测资料,结合西北太平洋热带气旋年鉴资料,统计和分析了热带气旋对长江口区的影响规律,统计结果显示,在近24 a中,热带气旋年均有2.0个,通常出现在6-10月期间,以8月份最多,发生频数为45.8%;严重影响长江口区的热带气旋年均只有0.3个,有60%集中在8月份,都属海上转向型;影响长江口的热带气旋源区90%位于菲律宾和琉球群岛以东洋面,且有超过一半生成于10°N～20°N;影响长江口区热带气旋次数存在4～6 a的小周期波动和10 a左右的周期变化,并且在厄尔尼诺年的影响次数较反厄尔尼诺年少.

In the light of the annual data of Northwest Pacific Ocean tropic cyclone, the influence of the tropic cyclone on the Changjiang estuary has been analyzed according to the observation data from the Dajishan, Yinshuichuan hydrological observation station. The research results show that the annual average number of tropic cyclone is 2.0, which occurs frequently from June to October, and the highest possibility in August is 45.8 %, whereas that of the tropic cyclone that influences the Changjiang estuary seriously is only 0.3. It takes place in August with a probability of 60 %. Among the tropic cyclones that influence the Changjiang estuary, about 90% is formed on the ocean to the east of the Philippines and Ryukyu-retto, and more than half at 10°N - 20°N. The occurring frequency of the tropic cyclone vibrates between 4 to 6 years and shows 10 years' periodic change. They appear more in anti-ElNi n o years than in ElNi n o years. ~ ~