Study On Typical Process Of Winds That Exceed Flight Training Standards At Guanghan Airport Based On Wind Lidar

Gale is a serious threat to low-altitude flight safety.The analysis of the refined structure of gale evolution based on the new detection technology is of great significance for the improvement of aviation meteorological support capability.Based on the evaluation of the performance of the laser lidar,the common thunderstorms and frontal gales at Guanghan Airport were analyzed by using the coherent Doppler lidar.The results show that:(1)the detection efficiency of low elevation PPI of the lidar is better within 4.5km,and then the detection efficiency decreases obviously with the increase of distance.During RHI scanning,the vertical detection height is mainly within 2km.Further analysis showed that the detection distance was negatively correlated with the logarithm of hourly rainfall and positively correlated with PM2.5 concentration.(2)The analysis on the process of a summer thunderstorm gale on July 18,2020 shows that before the thunderstorm,the lidar can better capture the lowlevel jet with strong northwest wind near 1500 m in the altitude,accompanied by strong sinking motion,which is an important environmental condition for the occurrence of thunderstorms,and also leads to winds that exceed flight training standards on the surface burst out.Through detailed observation,it can be found that there is an obvious three-layer wind structure in the low-altitude vertical wind field in the glide path.With the change of time,the near-surface wind direction changes from upwind to downwind and the downwind wind speed increases continuously.In horizontal wind field,the movement process of wind speed profile 6m/s and the time affecting ground takeoff and landing can be found.This process strongly affects the flight training at 1000-2000 m altitude.(3)The analysis of the frontal gale from December 13 to 14,2020 shows that a large wind core with an average wind speed of more than 14m/s appeared in the altitude layer 500-1000 m above the ground during 14:00 to 21:00 on December13.During the occurrence of the period of winds that exceed flight training standards on the surface,the downdraft over the airport continues to be strong,which plays a role in promoting the occurrence of surface wind.Different scanning methods of lidar reflect that the upper-level wind has an obvious downward momentum transmission process.As the cold air intrudes into the field at mid-low altitude,the upper-level wind first reaches the airport and forms a strong wind speed center,which gradually descends and affects the field,and then the exceed flight training standard wind phenomenon appears on the ground.The occurrence time of exceed flight training standard wind on the ground lags behind the occurrence time of high-altitude wind by about 2 hours,and the end time lags behind by about 4 hours.During the transit of winter front,the airport is affected by it for a long time and the wind speed is high.The wind speed profile such as 8m/s continues to extend to the vicinity of the airport lidar.Meanwhile,special attention should be paid to the rapid change of wind speed near the flight altitude of500 m and 1000 m.