Use of Specific Attenuation for Rainfall Measurement at X-Band Radar Wavelengths. Part I: Radar Calibration and Partial Beam Blockage Estimation
Use of Specific Attenuation for Rainfall Measurement at X-Band Radar Wavelengths. Part I: Radar Calibration and Partial Beam Blockage Estimation
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DOI：
10.1175/jhm-d-14-0066.1
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发表时间：
2015-04-01
影响因子：
3.8
通讯作者：
Troemel, Silke
中科院分区：
文献类型：
--
作者：
Diederich, Malte;Ryzhkov, Alexander;Troemel, Silke
在一篇由两部分组成的论文中，Ryzhkov 等人建议使用特定衰减 A 进行雷达降雨率反演。都受到彻底调查。 2011-13 年夏季，德国两台双偏振 X 波段天气雷达的连续重叠测量数据被用于分析降雨率反演的各个方面，包括校准误差校正、地杂波污染和部分波束遮挡 (PBB) 的缓解、对降水特性的敏感性以及 R(A) 技术的温度假设。在本文中，R(A) 方法固有的关系用于根据 A 估计雷达反射率 Z，并将其与测量的 Z 进行比较，以便估计两个雷达的 PBB 和校准偏移。两个雷达从 A 估计的 Z 场是一致的，并且 Z(A) 和测量的 Z 之间的差异与使用水平偏振反射率 Z(H)、微分反射率 Z(DR) 和雨中特定微分相位 K-DP 之间的一致性关系或存在 PBB 的数字高程模型计算的结果非常一致。在分析中，A 对温度的依赖性似乎对该方法的整体性能影响最小。正如预期的那样，Z(A) 和衰减校正测量 Z 观测值之间的差异随降雨类型的不同而变化，并且对降雨强度表现出较弱的系统依赖性；因此，需要对几次降雨事件进行平均，以获得由雷达误校准和 PBB 引起的 Z 偏差的可靠估计。
In a two-part paper, radar rain-rate retrievals using specific attenuation A suggested by Ryzhkov et al. are thoroughly investigated. Continuous time series of overlapping measurements from two twin polarimetric X-band weather radars in Germany during the summers of 2011-13 are used to analyze various aspects of rain-rate retrieval, including miscalibration correction, mitigation of ground clutter contamination and partial beam blockage (PBB), sensitivity to precipitation characteristics, and the temperature assumptions of the R(A) technique. In this paper, the relations inherent to the R(A) method are used to estimate radar reflectivity Z from A and compare it to the measured Z in order to estimate PBB and calibration offsets for both radars. The fields of Z estimated from A for both radars are consistent, and the differences between Z(A) and measured Z are in good agreement with the ones calculated using either consistency relations between reflectivity at horizontal polarization Z(H), differential reflectivity Z(DR), and specific differential phase K-DP in rain or a digital elevation model in the presence of PBB. In the analysis, the dependence of A on temperature appears to have minimal effects on the overall performance of the method. As expected, the difference between Z(A) and attenuation-corrected measured Z observations varies with rain type and exhibits a weak systematic dependency on rainfall intensity; thus, averaging over several rain events is required to obtain reliable estimates of the Z biases caused by radar miscalibration and PBB.