风廓线雷达在白鹤滩峡谷区风场探测的应用分析

Application analysis of wind profile in wind field detection in Baihetan Canyon area

本文利用白鹤滩水电站峡谷区2020年11月—2021年7月的观测数据,选择多种风场变化情景时段,将边界层风廓线雷达与地面和高空观测结果进行对比分析,以检验风廓线雷达在特殊地形下的探测效果。结果表明:(1)风廓线雷达能够准确捕捉到低空0.5~1 km的风速演变信息,且能够反映边界层低空急流和2~3 km低空急流的发展,以及山谷风的转换时间,雷达数据获取率在地面低风速时段较强风速时段高,但受自身探测体制的制约和山区峡谷特殊地形的影响,雷达在0.5 km以下获取的有效数据量少,且探测的风向风速与地面观测存在不一致,在低风速时段还有风速瞬时异常增大现象。(2)在峡谷区大风伴随降水天气中,风廓线雷达探测有效数据的高度增加且整层数据获取率增加,其中0.7~3.5 km数据获取率大于90%。且能够探测2~3 km的强垂直风切变及其高度变化。当降水增强时,雷达探测的大气折射率结构常数和垂直风速值都会显著增大,且大值区高度上升。(3)对比风廓线雷达与ERA5再分析数据和探空观测的结果,发现在4 km以下雷达探测结果稳定,在4 km以上由于雷达探测体制的影响,探测结果不稳定。具体表现为雷达能够准确探测低空急流高度和强度,并获取1~4 km冷暖平流特性。

Based on the observation data from the gorge area of the Baihetan Hydropower Station from November 2020 to July 2021,various wind field change scenarios were selected to conduct a comparative analysis between the boundary layer wind profile radar and ground-level and upper-air observations.This aimed to assess the detection performance of the wind profile radar in special terrain conditions.Results are as follows:(1)the wind profile radar is capable of accurately capturing wind speed evolution information at low altitudes of 0.5-1 km.It can also reflect the development of boundary layer low-level jets and 2-3 km low-level jets,as well as the transition time of mountain and valley winds.The radar data acquisition rate is higher in the period of low surface wind speed than that in the period of strong wind speed.However,due to limitations inherent in its detection system and the unique terrain of the mountain gorge,the radar has limited effective data acquisition below 0.5 km.Additionally,there are inconsistencies in the detected wind direction and speed compared to ground observations,with occasional instances of abnormal wind speed spikes during low wind speed periods.(2)During windy weather accompanied by precipitation in the gorge area,the height of valid data detected by the wind profile radar increases,and the overall data acquisition rate improves.Specifically,the data acquisition rate at 0.7-3.5 km exceeds 90%.The radar is also capable of detecting strong vertical wind shear and its height variations at 2-3 km.As precipitation intensity increases,both the atmospheric refractive index structure constant and vertical wind speed detected by the radar increase significantly,with the height of the higher values also rising.(3)When comparing the results of the wind profile radar with those of the ERA5 reanalysis data and radiosonde observations,it is evident that the radar detection results are stable below 4 km.Above this altitude,however,the detection results become unstable due to the influence of the radar s detection system.Specifically,the radar is able to accurately detect the height and intensity of low-level jets and capture the characteristics of warm and cold advection at altitudes ranging from 1-4 km.