C波段双偏振天气雷达降雨和部分地形遮挡衰减订正研究

天气雷达可为中尺度对流系统研究提供高时空分辨率资料, 但降雨衰减和地形遮挡等因子会对雷达信号产生严重影响。针对广东省韶关市新丰县C波段双偏振天气雷达, 选取了2018年6月8日台风“艾云尼”、8月30日华南季风降水和9月16日台风“山竹”三次降雨过程, 采用基于差分相位(Φ_DP)数据的扩展自适应降雨廓线算法对雷达反射率因子(Z_H)数据进行了降雨衰减和部分地形遮挡衰减订正研究, 并将订正结果与广州S波段双偏振天气雷达探测结果进行了直接对比检验, 与中国气象局龙门云物理野外科学试验基地的4台二维视频雨滴谱仪(2D Video Distrometer, 2DVD)实测雨滴谱数据反演的雷达仿真探测量及国内外Z_H-K_DP经验统计公式进行了间接对比检验, 获得较好结果。最后选择具体降雨个例, 订正结果清晰展现了台风螺旋雨带中对流单体雷达回波强度从地面到高空的垂直结构特征, 提高了复杂地形区域雷达对极端天气的近地面探测能力。 

CORRECTION OF RAINFALL ATTENUATION AND PARTIAL TERRAIN BLOCKAGE FOR C-BAND DUAL POLARIZATION WEATHER RADAR

Weather radar can provide high spatio-temporal resolution observational data for the studies related to mesoscale convective systems. Nevertheless, the attenuation caused by rainfall and complex terrain could seriously affect radar signals. In this paper, three severe rainfall processes in 2018 are comprehensively investigated using the C-band dual polarization weather radar data collected at Xinfeng of Guangdong Province. The three rainfall processes include the severe tropical storm Ewiniar on June 8, the monsoon rainfall in South China on August 30, and the super typhoon Mangkhut on September 16. Based on Φ_DP data, an adaptive algorithm for rainfall profile is developed to correct the Z_H attenuation induced by rainfall and partial terrain blockage. And then the results after correction are directly compared with the Z_H of S-band dual polarization weather radar data collected at Guangzhou. The comparison has been conducted further against the simulated radar data by using the four sets of 2 D video raindrop spectrum data acquired at the Longmen Field Experiment Base for Cloud Physics, China Meteorological Administration. Moreover, the corrected results are validated using the empirical statistical formulas of Z_H-K_DP. This shows that the correction algorithm could improve radar reflectivity data to some extent. Finally, the case study shows that the ground-to-high-level vertical structure of the radar reflectivity of convective cells in the spiral rain belt could be clearly presented. This correction algorithm could effectively improve the near ground observation ability of weather radars in complex terrain.