乌鲁木齐机场“6·11”强对流天气环境场及雷达回波特征分析

Analysis of Environmental Field and Radar Echo Characteristics of “6.11” Severe Convective Weather in Urumqi Airport

本文利用NECP 1˚ × 1˚逐6小时的再分析资料、常规气象观测资料、乌鲁木齐机场自动观测资料(AWOS)及雷达等资料,对乌鲁木齐机场2021年6月11日雷雨大风的环流条件及雷达回波的特征进行分析,结果表明:1) 机场雷雨大风发生在西伯利亚槽底短波槽东移南下,新疆多短波活动,高低空西南急流、低空风切变和强冷平流的有利环流背景下。2) 强对流发生前,机场各指数表明大气处于层结不稳定状态,具有不稳定能量,低空3公里下水汽充足,有明显的水汽辐合,为水汽饱和,“低层辐合、高层辐散”的抽吸作用使上升运动加强,地面辐合线提供触发机制,具备雷暴发生的三要素。3) 雷达回波图像在对流性天气的临近预报中具有重要指示意义,多个中γ尺度对流单体在对流风暴右侧不断生成,然后在东移过程中增长、成熟、衰减,引起机场雷雨大风天气。

Based on NECP 1˚ × 1˚ 6-hour reanalysis data, conventional meteorological data, Urumqi airport automatic observation data (AWOS) and radar data, this paper analyzes the circulation conditions and radar echo characteristics of thunderstorm and gale at Urumqi airport on June 11, 2021. The results show that: 1) The thunderstorm and gale occurred under the favorable circulation background of Siberian trough bottom short-wave trough moving eastward and southward, Xinjiang multi-short-wave activity, southwest jet at high and low levels, low-level wind shear and strong cold advection. 2) Before the occurrence of strong convection, the airport indexes indicate that the atmosphere is in a stratified unstable state with unstable energy, sufficient water vapor at low altitude 3 km, with obvious water vapor convergence, which is saturated for water vapor. The suction effect of “low-level convergence and high-level divergence” strengthens the upward movement, and the ground convergence line provides a trigger mechanism, which has three elements of thunderstorm occurrence. 3) Radar echo images have important indicative significance in the near forecast of convective weather. Several medium-γ-scale convective cells are continuously generated on the right side of convective storm, and then grow, mature and decay in the process of moving eastward, resulting in thunderstorm and gale weather at airport.