乌鲁木齐机场一次强对流天气的环境条件及雷达回波特征分析

Analysis of Environmental Conditions and Radar Echo Characteristics of a Severe Convective Weather at Urumqi Airport

本文利用FNL 0.25˚ ×0.25˚逐6小时再分析资料、加密自动站、雷达资料等,对2022年6月28日乌鲁木齐机场雷雨大风天气过程的发生发展的环境条件及雷达回波特征进行分析,结果表明:1) 此次强对流天气过程发生在较强西风气流中短波影响背景下,中低层风速辐合区、辐合切变区、低空急流等为强对流提供了较好的大尺度强迫抬升条件。2) 强对流发生前,北疆区域处于明显的热力不稳定环境中,强对流发生区域对流能量的释放与500 hPa和850 hPa假相当位温差及对流有效位能的变化有较好的对应关系。乌鲁木齐机场的探空曲线结构呈现上下干、中层湿的结构,与机场出现弱降水和雷暴大风相对应。3) 影响乌鲁木齐机场的强对流云团是由多个中γ尺度对流单体合并加强并迅速东南移动引起,雷达回波图像清晰地再现了整个发展过程。该中尺度雷暴系统是在较强的露点梯度区和地面中尺度辐合线上触发的,对流触发后强烈的上升运动和水汽的迅速汇聚使得中尺度雷暴系统得以长时间发展和维持。

Based on the 6-hour reanalysis data of FNL 0.25˚ ×0.25˚, encrypted automatic station and radar data, this paper analyzes the environmental conditions and radar echo characteristics of the occur-rence and development of the thunderstorm and gale weather process at Urumqi airport on June 28, 2022. The results show that: 1) This strong convective weather process occurred under the back-ground of strong westerly flow and short wave influence, and the convergence area, convergence shear area and the low-level jet provides better large-scale forced lifting conditions for strong convection. 2) Before the occurrence of strong convection, the northern Xinjiang region was in an obvious thermal unstable environment. The release of convective energy in the region where strong convection occurred had a good relationship with the change of 500 hPa and 850 hPa pseudo equivalent potential temperature difference and convective effective potential energy. The sounding curve structure of Urumqi airport presents the structure of upper and lower dry and middle wet, which corresponds to the weak precipitation and thunderstorm gale at the airport. 3) The strong convective cloud cluster affecting Urumqi airport is caused by the merger and strengthening of multiple meso-γ-scale convective cells and the rapid southeast movement. The radar echo image clearly reproduces the entire development process. The mesoscale thunderstorm system is triggered in the strong dew point gradient area and the ground mesoscale convergence line. After the convection is triggered, the strong upward movement and the rapid convergence of water vapor make the mesoscale thunderstorm system develop and maintain for a long time.