| 南海台风生成前48 h环流特征及热力与动力条件 |
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| 引用本文： | 高拴柱,张胜军,吕心艳,魏凤英.南海台风生成前48 h环流特征及热力与动力条件[J].应用气象学报,2021,32(3):272-288. |
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| 作者姓名： | 高拴柱 张胜军 吕心艳 魏凤英 |
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| 作者单位： | 1.国家气象中心, 北京 100081 |
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| 摘 要： | 利用1979—2019年4—11月中国气象局上海台风研究所热带气旋最佳路径资料和静止卫星红外云图资料，筛选出189例南海台风，结合欧洲中期天气预报中心1°×1°再分析资料，分析南海台风生成前48 h至生成时刻的天气环流和动力、热力条件。结果表明:南海台风生成于热带洋面大范围的高海表温度、高水汽含量和高不稳定层结区，其生成前的主要环境背景环流是赤道辐合带、西南季风或东风波等；台风生成前扰动中心常常处于其北侧风切变小而南侧风切变大的过渡带中，少数扰动中心倾向于风切变小值中心附近，风切变与扰动的发展之间无显著相关；扰动中心一般与垂直涡度中心重合，垂直涡度中心是表征扰动自身强弱的物理量，但垂直涡度自身的大小与未来扰动发展趋势关系不明显，而Okubo-Weiss（OW）指数则对于扰动的发展以及扰动位置确定有较好的指示意义；在扰动发展过程中，扰动中心附近存在一个贯穿整个对流层的位涡柱，低层扰动部分与位涡柱中的中低层位涡相互作用，有利于扰动发展。
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| 关 键 词： | 南海台风 台风生成 环流特征 |
| 收稿时间： | 2021-01-28 |
Circulation Characteristics and Thermal and Dynamic Conditions 48 Hours Before Typhoon Formation in the South China Sea |
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| Affiliation: | 1.National Meteorological Center, Beijing 1000812.State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081 |
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| Abstract: | Based on the tropical cyclone best track data from Shanghai Typhoon Institute of China Meteorological Administration and the geostationary infrared satellite cloud image from April to November during 1979-2019, 189 typhoons formed in the South China Sea are selected as target cases. The circulation characteristics, dynamic and thermal conditions from 48 hours before typhoon formation to the time of typhoon generation are analyzed using the reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF) with 1°×1° grid. The results indicate that the typhoon in the South China Sea is formed in a large range of tropical ocean with high surface temperature, high water vapor content and unstable stratification. The development of deep convection and its distance to the tropical disturbance center can be used as an observation criterion for whether the tropical disturbance can develop into typhoon in the next 48 hours. Intertropical convergence is the dominant background circulation of typhoon formation in the South China Sea, and south-west monsoon or easterly wave are also main large-scale circulation. The center of typhoon disturbance is often in the transition zone of the vertical shear, where the vertical shear of the north side of the disturbance becomes smaller and the vertical shear of the south side becomes larger. Sometimes the disturbance center is slightly inclined to the weak vertical shear center. As a whole, there is no significant correlation between wind vertical shear and typhoon disturbance development. The center of tropical disturbance generally coincides with the center of vertical vorticity, and the center of vertical vorticity could be considered as a physical quantity representing the strength of disturbance itself. Furthermore, it is difficult to define the development of the vertical vorticity as an indicator to characterize the development trend of disturbance, while the Okubo-Weiss (OW) index is a good indicator for the development of disturbance and the determination of the disturbance location. In the process of typhoon disturbance development, there is a potential vortex column running through the whole troposphere near the disturbance center. Within the potential vortex column near the disturbance center, the interaction between lower disturbance and the potential vortex in middle and low layer is beneficial to the development of typhoon disturbance. |
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