测风激光雷达在青岛低能见度天气下的适用性

Wind Lidar Applicability in Low Visibility Weather in Qingdao

利用2021年4月—2022年12月青岛国家基本气象站多普勒测风激光雷达和L波段探空系统低空风场观测数据,对比非降水时低能见度天气下测风激光雷达的探测高度和精度。结果表明:测风激光雷达在青岛地区具有良好的适用性,在能见度大于10000 m的非降水天气,其平均最大探测高度稳定在约1200 m,水平风速均方根误差约为1.2 m·s^(-1),水平风向均方根误差约为25°。在能见度小于10000 m的低能见度天气下,测风激光雷达在不同能见度和相对湿度范围内的探测高度和精度受干扰程度存在差异。在能见度为1000~10000 m、相对湿度小于90%的霾天,此时大气能见度降低主要是气溶胶粒子含量增加所致,测风激光雷达的探测能力与高能见度天气下相当。当相对湿度高于95%时,此时大气能见度降低是空气中水汽含量的增加所致,严重干扰了激光在大气中的传输,测风激光雷达的探测高度和精度均有所降低,尤其在能见度小于1000 m的雾天,需谨慎使用其风速和风向数据。

Utilizing data of Doppler wind lidar and L-band radiosonde system installed at Qingdao National Basic Meteorological Observing Station from April 2021 to December 2022,their detection capability and accuracy under low visibility weather conditions are compared and evaluated,specifically in terms of detection height,horizontal wind speed and wind direction,using data obtained from L-band radiosonde system as the reference standard.During non-precipitation weather,when visibility exceeds 10000 m,the wind lidar demonstrates a stable average maximum detection height of approximately 1200 m.The root mean square errors of the wind speed and direction fluctuate around 1.2 m·s^(-1)and 25°,respectively.However,when the visibility drops below 10000 m,the detection height and accuracy of the wind lidar are influenced by the level of interference,particularly in different visibility and relative humidity ranges.In situations where visibility is below 1000 m,the decrease in atmospheric visibility is attributed to increased water vapor content in the air,with relative humidity consistently exceeding 95%.This high humidity significantly interferes with laser transmission in the atmosphere,resulting in an average maximum detection height of less than 400 m.The correlation between horizontal wind speed and direction decreases to 0.91 and 0.94,and the root mean square error increases to 1.4 m·s^(-1)and 42.7°,respectively.When the visibility ranges between 1000 m and 10000 m,the wind lidar's detection capability varies with the water vapor content in the atmosphere.In cases where relative humidity is below 90%,meeting the criteria for hazy days,the decrease in atmospheric visibility is primarily due to increased aerosol particle content.Under these conditions,the average maximum detection height remains stable above 1200 m.The correlation coefficients for horizontal wind speed and direction are as high as 0.97 and 0.98,with root mean square errors of about 1.1 m·s^(-1)and 22.3°,respectively.These results are comparable to the detection capability demonstrated under high visibility weather conditions.As relative humidity increases,the impact of water vapor attenuation on laser transmission starts to affect the detection height and accuracy of the wind lidar to varying degrees.When the relative humidity exceeds 95%,the average maximum detection height influenced by water vapor decreases to below 400 m.The correlation coefficient of wind speed decreases to 0.94,with a corresponding increase in the root mean square error to 1.5 m·s^(-1),and the accuracy of wind direction remains relatively stable under these conditions.