南亚边缘海域热带气旋年频次与对流层风场变化的关系

利用1958-1998年NCAR/NCEP再分析资料和美国海军联合台风警报中心JTWC (Joint Typhoon Warning Center)提供的同时期南亚边缘海域(包括阿拉伯海、孟加拉湾和南海)热带气旋资料,分析了这3个海域热带风暴高发期气候上100hPa和850hPa风矢量特征,以及100hPa纬向风强度分别与这3个海域热带气旋年频次之间的关系。结果表明:在阿拉伯海及孟加拉湾热带气旋生成数与100?hPa东风气流强度之间存在极好的正相关关系,即东风气流加强热带气旋数目增多,反之减少。而南海由于位于南亚高压东南侧,经向风的显著地位使南海热带气旋与100hPa经向风强弱变化有联系而与纬向风的关系减弱。

The Relationship between the Tropical Cyclone Frequency over the South Asian Marginal Seas and Tropospheric Wind Variations

The climatically character of wind vectors at 100 hPa and 850 hPa level and the relationship between the tropical easterly current at the 100 hPa level and tropical cyclone numbers in low and high frequency years were analyzed by using the data of NCEP/NCAR reanalysis and the tropical cyclone data from JTWC(Joint Typhoon Warning Center) over the Arabian Sea,Bay of Bengal and the South China Sea during the period 1958-1998.The result shows that a high positive correlation between tropical easterly current and the number of tropical cyclone is found in the Arabian Sea,Bay of Bengal.However,such a positive correlation is not found in South China Sea.Because South China Sea is at the southeast of South Asia high,the domination of meridional wind makes the relationship between tropical cyclone numbers and the merridional wind at the 100 hPa level is higher than it between tropical cyclone numbers and tropical easterly.