5月孟加拉湾风暴不同移动路径典型个例的大气环境场对比分析

利用JTWC最佳路径数据集及欧洲中心ERA-Interim再分析资料,分析了5月孟加拉湾气旋和风暴的活动特征,并重点分析了4个不同路径的典型孟加拉湾风暴大气环境场差异,初步探讨了影响风暴移动的关键大气环流因子。研究表明:5月孟加拉湾风暴路径分为北上、东北移、西北移、转向4种,其中东北移路径最多,北上路径最少;孟加拉湾风暴的生成和移动与阿拉伯副热带高压和西太平洋副热带高压的相对强弱和位置,以及中高纬度槽脊波动密切联系,同时还与孟加拉湾风暴的生成位置有一定关系,10°N以北孟加拉湾海域生成的风暴容易东北移,10°N以南孟加拉湾海域生成的风暴却容易西北移,这与西太平洋副热带高压边缘不同引导气流的作用有关;孟加拉湾风暴移动路径还与高空急流变化有关,风暴有趋于高空急流右侧辐散区运动的趋势;孟加拉湾风暴生成于弱的垂直纬向风切变区,纬向风移动增强的方向指示孟加拉湾风暴移动的方向。

Effect of atmospheric environmental field on the moving path of storm over the Bay of Bengal in May

Based on the best track data of the Joint Typhoon Warning Center (JTWC) and the ERA-Interim reanalysis data from the European Center, the activity characteristics of cyclones and storms over the Bay of Bengal in May were analyzed, and the differences of atmospheric environmental fields of the typical storms over the Bay of Bengal with four different paths were emphatically analyzed, and the key atmospheric circulation factors affecting the movement of the storm were preliminarily discussed. Results show that, in May, the storm path over the Bay of Bengal is divided into four types:northward, northeast, northwest and steering, of which the northeast path is the most and the northerly path is the least. The generate and movement of storms over the Bay of Bengal are closely related to the relative strength and position of the Arab subtropical high and the western Pacific subtropical high, as well as to the fluctuation of trough ridges in the middle and high latitudes. At the same time, it is also related to the generation location of the storm over the Bay of Bengal. The storm generated north of 10°N Bay of Bengal sea area is easy to move northeast, while the storm generated north of 10°N Bay of Bengal sea area is easy to move northwest, which is related to the role of different guiding airflow at the edge of the West Pacific subtropical high. The moving path of the storm over the Bay of Bengal is also related to the variation of the upper-level jet, and the storm tends to move to the divergence area on the right side of the upper-level jet. The storm over the Bay of Bengal is generated in the weak vertical zonal wind shear region, and the direction of the zonal wind movement enhancement indicates the direction of the storm over the Bay of Bengal movement.