乌鲁木齐机场一次雷暴天气过程分析

Analysis of a Thunderstorm Process at Urumqi Airport

利用常规探测资料、FNL再分析资料(0.25˚ × 0.25˚)、多普勒雷达资料以及FY-4卫星资料等,着重对乌鲁木齐国际机场2022年7月17日一次雷暴天气过程的动力条件进行分析,得到以下结论:此次雷暴天气大尺度环流背景为500 hPa上偏西气流,多有短波分裂,配合700 hPa天山北坡有明显的风速辐合带、乌鲁木齐机场南侧西北风和西南风的风向切变、850 hPa上东南风和西南风的风向切变、以及地面不稳定低值区共同作用产生的。强盛的偏西、西南急流携带充足水汽输送至北疆西部以及天山北坡,且雷暴前期在乌鲁木齐机场南侧存在强烈的水汽辐合,配合垂直方向上高层辐散低层辐合的上升运动,为雷暴提供水汽和动力条件;南疆西部有高能舌东北伸,同时乌鲁木齐本场上空存在假相当位温等值线密集区,垂直方向上为中层向下渗透冷空气,低层相对高温高湿,为雷暴天气的发生积累了一定的位势不稳定能量。尺度小但强度强的孤立对流单体在东移过程中激发出新的单体导致了此次雷暴天气持续时间较长。

Using conventional sounding data, FNL reanalysis data (0.25˚ × 0.25˚), Doppler radar data, and FY-4 satellite data, analysis of the dynamical conditions of a thunderstorm weather process at Urumqi International Airport on July 17, 2022, conclusions are as follows: The large-scale circulation back-ground of this thunderstorm was westerly flow over 500 hPa, mostly with short-wave splitting, which was produced by the combination of obvious wind convergence zone on the north slope of Tianshan Mountain at 700 hPa, wind shear of northwest and southwest winds on the south side of Urumqi Airport, wind shear of southeast and southwest winds on 850 hPa, and low value area of ground instability. Strong westerly and southwest jets carry sufficient water vapor to the western part of northern Xinjiang and the Northern Slope of Tianshan Mountain. In the early stage of the thunderstorm, there was strong water vapor convergence on the south side of Urumqi Airport, which provided water vapor and dynamic conditions for the thunderstorm with the upward move-ment of upper level divergence and lower level convergence in the vertical direction. In the west of southern Xinjiang, there is a high energy in the northeast, and there is a dense area of pseu-do-equivalent temperature isocontors over Urumqi. In the vertical direction, the middle layer pen-etrates cold air downward, and the low layer is relatively high temperature and humidity, which accumulates a certain potential instability energy for the occurrence of thunderstorms. The small scale but strong isolated convective cells stimulated new cells during eastward movement, which led to the longer duration of the thunderstorm.