北疆偏西地区一次极端暴雨过程综合分析

Analysis of a Heavy Rain Weather Process in Bozhou, Xinjiang

本文利用常规观测资料、伊犁地区多普勒天气雷达产品、FY-2D卫星云图、不同尺度风速、散度、涡度等各类物理量,分析大尺度环流背景下2018年5月12日至15日发生在北疆偏西地区的一次大暴雨的形成过程。结果表明:1) 影响暴雨产生的主要原因是高空冷槽与地面冷锋的共同作用。2) 早在大暴雨发生前,该地区已发生相对较少的降水,这不仅有利于空气的湿润,还使得水汽循环加强,为大暴雨提供了水汽条件。3) 前期,底层辐合、高层辐散,以及上下层温度逆差造成层结不稳定等因素为暴雨的产生创造了热力、动力条件。因而,本次北疆偏西山区大暴雨的触发机制是位于巴尔喀什湖南侧温度槽南压、强烈而持续的上升运动和地形作用的共同影响。

This article uses conventional observation data, Doppler weather radar products in the Ili area, FY-2D satellite cloud images, wind speeds at different scales, divergence, vorticity and other physical quantities to analyze the large-scale circulation background from May 12 to 2018 the formation of a heavy rainstorm in Bozhou, Xinjiang on the 15th. The results show that: 1) The main reason for the occurrence of heavy rain in Bozhou is the joint action of the high-altitude cold trough and the ground cold front. 2) Prior to the occurrence of heavy rain, relatively little precipitation has occurred in the Bozhou area, which not only benefits the humidification of the air, but also strengthens the water vapor cycle, providing water vapor conditions for the heavy rain. 3) In the early stage, the convergence of the bottom layer, the divergence of the upper layer, and the unstable temperature stratification of the upper and lower layers have created thermal and dynamic conditions for the occurrence of heavy rain. Therefore, the trigger mechanism of the local heavy rain in the Bozhou region is the combined effect of the south pressure of the temperature trough located on the south side of the Balkhash Lake, the strong and continuous upward movement of the Bozhou region and the topographic effect.