Gaoyuan qixiang (Oct 2023)
Study of Low-Level Wind Shear and Its Evolution Based on LIDAR and Aircraft Reports Identification
Abstract
Low-level wind shear significantly impacts aviation safety and operational efficiency.Zhongchuan Airport， located in a mountainous inland region， experiences the influence of complex terrain and weather systems.Wind shear is frequently observed during the summer season.This study analyzes the spatial and temporal characteristics of low-level wind shear events at Zhongchuan Airport using aircraft reports spanning from 2009 to 2018.During the observation period from May 2016 to November 2017， a total of 18 low-level wind shear events were confirmed through aircraft verification.Two methods， namely the fixed and adaptive window methods， were compared to identify wind shear events using LIDAR data from the Windcube 400s-at instrument.The study also explored the continuous evolution and spatial characteristics of the three-dimensional wind shear structure.The results indicate that the frequency of low-level wind shear events has increased at a faster rate compared to the flight volume at Zhongchuan Airport over the past ten years.The peak months for low-level wind shear events at Zhongchuan Airport are April-July and August-October， influenced by local weather patterns.The peak months for low-level wind shear events at Zhongchuan Airport are April-July and August-October， influenced by local weather patterns.Wind shear induced by convective weather occurs in the weak or non-echo region surrounding the convective cloud， resulting from the convergence of updrafts and downdrafts outside the cloud， or the formation of a gust front following the downdraft's contact with the ground.The wind shear factor is correlated with the intensity of radar echoes.Compared to the fixed window method， the adaptive window method had a larger recognition range due to the different data sets included in the recognition window.Therefore， the adaptive window method was found to be more suitable for studying the three-dimensional evolution of wind shear structures.Therefore， the adaptive window method is better suited for studying the evolution of the three-dimensional wind shear structure.The wind shear in the vicinity of Zhongchuan Airport is characterized by a low spatial distribution， small horizontal scale， and short duration， primarily concentrated in the small-scale and γ mesoscale.In other words， the wind shear events occurred at relatively low altitudes， with horizontal scales mostly ranging between 1000~1500 m and 2000~2600 m， lasting less than 20 minutes.Furthermore， 40.5% of the wind shear events were attributed to the movement of the wind， primarily influenced by the background wind.The findings of this study contribute to a better understanding of the characteristics of wind shear， offering valuable insights for the identification， mechanisms， forecasting， and early warning of low-level wind shear events at Zhongchuan Airport.
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