Analysis of LiDAR in a cold front low-level wind shear in Urumqi Airport

In order to study the characteristics of the structure of wind shear, the low-level wind shear at Urumqi Airport on 2021-11-26 was analyzed by using the FC-Ⅲ wind light detection and ranging(LiDAR) data, the reanalysis data of National Centers for Environmental Prediction, and conventional meteorological observation data. The evolution of wind shear was calculated. The results show that, the wind shear process occurred under the condition of a specific terrain wind. The small scale of cold air caused the significant changes in wind direction and speed, the bottom of the southeast jet and the northwest wind belt form a vertical shear area inclined upward which led to the cold-front type of low-level wind shear. The wind field around airports had been changed 1 h before the occurrence of wind shear. And the wind shear area was detected 10 min earlier than the report from aircraft which based on the plan position indicator model, the area where wind shear occurred was significant variations in the southeast wind speed, and also followed the movement of cold air to the west. During the movement of cold air, the southeast wind layer became thinner and retreated to the west. Near the glide path 07^#. There was not only a sharp reduction of the frontal crosswind, but also a significant change in wind direction. The cold air was wedged from 25^# to 07^# during 08:30~10:25. The small-scale of cold air activity at low altitude was captured, and a backward of evolution process and structure was figured out, which showed that the pathway entering the airport from northeast, and issued the wind shear warning. The study is helpful to improve the meteorological service support capacity.