乌鲁木齐机场一次间歇性雷雨天气过程诊断分析

Diagnosis and Analysis of an Intermittent Thunderstorm in Urumqi Airport

摘要: 本文利用1˚ × 1˚的NCEP再分析资料，通过对环流形势及影响系统、不稳定层结、水汽条件、抬升触发机制等方面进行初步诊断分析。结果表明：1) 本次天气过程的环流背景：西西伯利亚低涡稳定在80˚E60˚N附近，不断分裂短波槽影响北疆。地面冷高压主体位于乌拉尔山–咸海一带，其前部不断分裂冷空气堆积在巴尔喀什湖南侧，随后逐步入侵北疆，15日~16日，冷高压主体逐步东移，冷空气进一步补充再次影响北疆大部。2) 本次天气过程具有持续时间久但不连续，覆盖面积广且局地性强的特点。3) 高低空影响系统近乎垂直，大气层结易形成“上冷下暖”的热力不稳定状态。4) 对流层中低层巴尔喀什湖南侧偏西、西南气流，涡后脊前西北气流为北疆区域输送了一定的水汽。5) 垂直方向上风向随着高度先顺时针旋转再逆时针旋转，说明低层有冷平流，中层有暖平流，表明大气层结处于位势不稳定状态，有利于强对流天气的发生与维持。6) 对流层低层转为西北风或西北风风速增大，有利于与地形结合，促进垂直上升运动，触发强对流天气。

Abstract: Based on the NCEP reanalysis data of 1˚ × 1˚, this paper makes a preliminary diagnosis and analysis of circulation situation and influence system, unstable stratification, water vapor conditions and trigger mechanism of uplift. The results show that: 1) The circulation background of this weather process: the low vortex in Western Siberia is stable around 80˚E60˚N, and the short-wave trough affects northern Xinjiang constantly. The main body of surface cold high pressure is located in the Urals Mountains to the Aral Sea area, and the front of the cold air is constantly splitting and accumulating on the south side of Balkhash Lake, and then gradually invading northern Xinjiang. From 15th to 16th, the main body of cold high pressure gradually moved eastward, and the cold air further supplemented and affected most of northern Xinjiang again. 2) The weather process has the characteristics of long duration but discontinuity, wide coverage area but strong locality. 3) The effect of high and low space on the system is almost vertical, and the atmospheric junction is easy to form a thermal unstable state of “upper cold and lower warm”. 4) The west-southwest air flow in the south side of Balkhash Lake in the middle and lower troposphere, and the northwest air flow in front of the rear vortex ridge transported some water vapor to the northern Xinjiang region. 5) The vertical upwind first rotates clockwise and then counterclockwise with height, indicating that there is a cold advection in the lower layer and a warm advection in the middle layer, indicating that the atmospheric junction is in a potential unstable state, which is conducive to the occurrence and maintenance of strong convective weather. 6) The lower troposphere becomes northwest wind or northwest wind speed increases, which is conducive to combining with terrain, promoting vertical upward movement and triggering strong convective weather.