影响北印度洋热带气旋生成环境因子的月际变化特征  

Monthly variation characteristics of environmental factors affecting tropical cyclone genesis over the North Indian Ocean

作　　者：柳龙生 张新忠 许映龙 LIU Longsheng;ZHANG Xingzhong;XU Yinglong(National Meteorological Center,Beijing 100081,China;Beijing Presky Technology Company Limited,Beijing 100195,China)

机构地区：[1]国家气象中心,北京100081 [2]北京弘象科技有限公司,北京100195

出　　处：《干旱气象》2022年第3期375-385,共11页Journal of Arid Meteorology

基　　金：国家自然科学基金项目(41930972);国家重点研发计划(2019YFC1510102)共同资助。

摘　　要：利用美国联合台风警报中心(Joint Typhoon Warning Centre,JTWC)发布的1979—2018年北印度洋热带气旋(tropical cyclone,TC)数据和ERA-Interim提供的分辨率为1°×1°的同期再分析资料,分析影响北印度洋热带气旋生成的不同环境因子月际变化特征。结果表明:5月北印度洋海温明显增暖,适宜的200 hPa与850 hPa垂直风速切变(5~10 m·s^(-1))和充足的水汽供应使得热带气旋的生成数达到全年第一个峰值。7—9月对流层中低层相对湿度条件很好,但200 hPa与850 hPa垂直风速切变过大,使得扰动对流很难形成暖心结构,不利于热带气旋的生成。10—11月北印度洋平均海温27~29℃,中层大气相对湿度条件较好,850 hPa多气旋性环流,200 hPa与850 hPa垂直风速切变为5~15 m·s^(-1),在这种有利的环境条件下北印度洋热带气旋生成数达到全年第二个峰值。对影响北印度洋两个海域热带气旋月际变化的不同环境因子定量研究发现,尽管阿拉伯海和孟加拉湾的热带气旋生成数都呈现双峰型变化,但环境因子在相同月份却呈现不一样的特征。Based on the tropical cyclone data in the North Indian Ocean released by the Joint Typhoon Warning Center(JTWC)and the synchronous reanalysis data with a resolution of 1°×1°from ERA-interim during 1979-2018,a study was conducted to investigate the monthly characteristics of different environmental factors affecting the tropical cyclone genesis over the North Indian Ocean.The results show that the sea surface temperature of the North Indian Ocean increased significantly,with moderate vertical wind shear(5-10 m·s^(-1))between 200 hPa and 850 hPa and sufficient water vapor supply in May,which led to the first peak of tropical cyclones of the whole year.From July to September,the relative humidity in the middle and lower troposphere was very plenty.However,due to the large vertical wind shear between 200 hPa and 850 hPa,it was difficult for disturbed convection to form a warm center structure,which was not conducive to the generation of tropical cyclones.From October to November,the average sea surface temperature of the North Indian Ocean was 27-29℃,accompanying with higher relative humidity of the middle atmosphere and more cyclonic circulation at 850 hPa.The vertical wind shear between 200 hPa and 850 hPa was reduced to 5-15 m·s^(-1).Under these favorable environmental conditions,the generation of tropical cyclones over the North Indian Ocean reached the second peak of the whole year.Through quantitative study of different environmental factors affecting the monthly variability of tropical cyclones in two sea areas of the North Indian Ocean,it was found that although the number of tropical cyclones generated over the Arabian Sea and the Bay of Bengal assumed a bimodal monthly variation,the environmental factors presented different characteristics in the same month.

关 键 词：北印度洋 热带气旋 环境因子 月际变化 

分 类 号：P444[天文地球—大气科学及气象学]