| 摘要: |
| 2018年5月21日夜间至22日白天，重庆市永川地区出现了一次强对流天气过程。为了更深入地认识强对流天气过程中大尺度系统与中小尺度系统的作用机制，提高永川地区强对流天气预报能力，文章利用常规地面观测资料、探空资料、多普勒天气雷达CINRAD/SA探测资料及FY4A卫星红外C011资料，采用天气动力学诊断方法，分析此次强对流天气过程。结果表明：（1）21日夜间至22日白天，中高纬度的低槽东移，副热带高压略有南移，中低层系统对峙，形成低涡切变线稳定少动，不断激发中小尺度扰动，使对流云团发展。（2）对流云团在低涡的辐合动力作用和暖湿条件下发展为MCC，孤立的对流单体发展成为飑线，东移过程中演变为弓形，大风出现在飑线强回波带、回波前沿，强降水主要发生在强回波区及回波后侧。（3）大气处于上干下湿的不稳定状态，强的CAPE指数、SI指数、K指数、LI指数显示热力、动力条件较好，同时垂直风切变较强，有利于飑线中的上升、下沉气流共存以及暖湿气流输送到发展的上升气流中，以致出现大风、短时强降水。中高纬度的低槽、副热带高压、低涡切变线等天气尺度系统与MCC、飑线等中小尺度系统共同作用，配合较好的热力、动力条件，以及较强的垂直风切变与水汽辐合中心，形成了此次强对流天气过程。 |
| 关键词: 强对流天气；MCC；飑线；强垂直风切变 |
| DOI： |
| 投稿时间：2018-11-29修订日期：2019-04-24 |
| 基金项目: |
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| Aanlysis of the Severe Convective Weather Process in Chongqing Yongchuan on 21 May 2018 |
| DONG Dan-dan,ZHANG Jian-ping,HE Qing-qing,YAN Meng-ling,DENG Xia |
| (Yongchuan Meteorological Bureau;Chongqing Institute of Meteorological sciences) |
| Abstract: |
| During the night of May 21, 2018 to the day of May 22, severe convective weather process appeares in Yongchuan area of Chongqing. At present, there is a lack of severe convective weather forecasting technology in Yongchuan area. In order to better understand the mechanism of the large scale system and the medium and small scale system in the process of severe convective weather, and improve the ability to forecast it in Yongchuan area. This paper uses dynamic diagnosis method with the routine surface abservation data、sounding data、doppler radar CINRAD/SA data and FY4A satellite infrared C011 image data to analysis the weather system evolution characteristics from May 20 to 22, 2018. The results show that: (1) During the night of May 21 to the day of May 22, the low trough in middle and high latitudes moves eastward, the subtropical anticyclone moves southward slightly, and the system in the middle and low levels confronts each other, forming a stable low vortex with shear line, which constantly stimulate meso-small scale weather system disturbances, with convective clouds developing. (2)And then convective clouds develop into MCC under the convergence dynamics of low vortex and sufficient warm and humid southwest airflow, isolated convection cell developing into squall line, moving eastward and evolving into a bow. The strong winds appeare in the strong echo zone and echo front of the squall line, and heavy rain mainly occurs in the strong echo area and the back of the echo. (3) The atmosphere is in an unstable state of upper dry and lower wet, and the high CAPE index, SI index, K index and LI index show better thermal and dynamic conditions, and strong vertical wind shear appears. At the same time, the vertical wind shear is strong, which is beneficial to coexistence of updraft and downdraft airflow in squall line and the warm moist airflow transported to the developing updraft airflow, then strong wind and short-term heavy rain show. Under the combined action of the synoptic scale systems (the low trough in middle and high latitudes, subtropical anticyclone and low vortex with shear line) and the mesoscale and small scale systems (MCC and squall line), with better thermal and dynamic conditions, strong vertical wind shear and water vapor convergence center appearing, this severe convective weather process forms. |
| Key words: severe convective weather; MCC; squall line; strong vertical wind shear |
