北京地区X波段双偏振天气雷达差分反射率因子系统偏差分析及订正  

Analysis and Correction of System Bias of Differential Reflectivity for X-Band Dual Polarization Radars in Beijing Area

作　　者：文浩[1,2] 王辉 张扬[4] 吴蕾[1] 李瑞义[1] WEN Hao;WANG Hui;ZHANG Yang;WU Lei;LI Ruiyi(Meteorological Observation Centre of China Meteorological Administration,Beijing 100081,China;Key Laboratory of Atmosphere Sounding,China Meteorological Administration,Chengdu 610103,Sichuan,China;Beijing Meteorological Observation Center,Beijing 100176,China;State Key Laboratory of Sever Weather,Chinese Academy of Meteorological Sciences,Beijing 100081,China)

机构地区：[1]中国气象局气象探测中心,北京100081 [2]中国气象局大气探测重点开放实验室,四川成都610103 [3]北京市气象探测中心,北京100176 [4]中国气象科学研究院,北京100081

出　　处：《高原气象》2025年第2期393-406,共14页Plateau Meteorology

基　　金：国家重点研发计划项目(2022YFC3003901);国家自然科学基金项目(42105141);中国气象局大气探测重点开放实验室联合基金项目(U2021Z10);中国气象局创新发展专项(CXFZ2024J058)。

摘　　要：差分反射率因子(ZDR)是反映大气中云和降水粒子形状的重要偏振参量,但其极易受硬件设备和环境影响导致质量变差,分析ZDR系统偏差并开展订正,是双偏振雷达数据有效应用的关键。本文采用2023年7月北京8部X波段速调管双偏振天气雷达资料,利用小雨法筛选出ZDR数据获得其逐仰角逐径向平均值,分析了ZDR的受影响因素和受影响程度;并利用相应时段的大量雨滴谱数据,通过T矩阵法计算的ZDR中值作为基准,开展全体扫ZDR的系统偏差订正。结果表明:(1)避雷针对于北京X波段雷达ZDR有较大的影响,影响范围在10°~25°,平均影响幅度在0.16~1.21 dB;(2)门头沟和怀柔雷达的ZDR数据,除受避雷针影响外,还分别受近距离铁塔、信号塔的影响,受影响方位角度小于避雷针;(3)差分反射率因子受部分波束遮挡会导致较大的系统偏差,房山X波段雷达ZDR数据显示部分波束遮挡可使其值增大1.19 dB;(4)本文提出的系统偏差订正方法能够明显改善所有仰角所有径向由避雷针、部分波束遮挡等因素导致的ZDR值不合理的情况。Differential reflectivity(ZDR)is a crucial polarimetric parameter reflecting the morphology of cloud and precipitation particles.However,the quality of ZDR is highly susceptible to decline due to hardware equipment and environmental influences.Analyzing biases in the measurement of ZDR and conducting corrections are key for the effective application of dual-polarization radar data.In this study,an analysis of the biases in ZDR is conducted,and corrective strategies are proposed based on data collected from light rain events by eight X-band dual-polarization radars in Beijing during July 2023.An adopted radial-by-radial accumulation method is employed to investigate factors and magnitudes influencing ZDR.Furthermore,the system bias of ZDR of full volume scans is corrected by using extensive raindrop spectrometer data during the corresponding period.The median value of ZDR computed via the T-matrix method of raindrop spectrometer data serves as the reference for the correction process.The following conclusions are drawn:(1)Lightning rods exert a significant influence on X-band radar’s ZDR in Beijing,with impact extending from 10°to 25°azimuth angles and average amplitude ranging from 0.16 dB to 1.21 dB.(2)ZDR data obtained from Mentougou and Huairou radars are not only affected by lightning rods but also by nearby iron towers and signal towers,with smaller azimuth angles of impact compared to lightning rods.(3)Partial beam blockage significantly affects ZDR,introducing notable systematic biases.For Fangshan X-band radar,partial beam blockage contributes to an increase of 1.19 dB in differential ZDR.(4)The proposed method for system bias correction demonstrates effective mitigation of unreasonable ZDR values attributed to factors such as lightning rods and beam blockage across all elevation angles and radial distances.

关 键 词：X波段 双偏振天气雷达 差分反射率因子 系统偏差 

分 类 号：P406[天文地球—大气科学及气象学]