PRELIMINARY ANALYSIS OF DATA QUALITY OF GUANGZHOU S-BANDPOLARIMETRIC WEATHER RADAR
-
摘要: 广东省已经通过新布设或对CINRAD\SA雷达的升级改造完成5部S波段双偏振雷达的业务运行。受目前双偏振雷达技术水平限制，双偏振雷达偏振量很不稳定，因此偏振雷达资料使用前需要对数据可用性、偏振量的系统偏差等进行初步分析，以保证偏振雷达后续产品的可靠性。使用广州S波段双偏振雷达稳定运行后的2016年7—8月连续观测资料，分析了噪声对零滞后相关系数ρHV(0)及差分反射率因子ZDR的影响和订正效果。结果表明：当SNR小于20.0 dB时，偏振参量ρHV(0)和ZDR的稳定性变差，数据不可用；噪声订正后，数据可用的SNR阈值减小为17.0 dB。进一步分析了经过噪声订正后的ZDR和ZH之间的关系，并与雨滴谱反演结果及理论值进行对比。结果表明：广州雷达ZDR较雨滴谱反演值和理论值均偏小，ZDR观测值存在系统偏差。结合广州的气候特征，对偏振量系统误差估计的微雨滴法的指数进行了调整，基于此方法分析了ZDR、初始相位ΦDP (0)的系统误差随方位角的变化。结果表明：ZDR系统误差随方位角在-0.29~0.22 dB之间波动，剔除遮挡后的平均偏差为-0.09 dB，与实测ZDR值和雨滴谱反演值及理论值对比偏小的结论一致，但偏差大小有区别；同时，ΦDP (0)随方位角有4 °左右的波动。分析还发现ZDR、ΦDP (0)系统误差有随时间波动的特征。最后挑选个例对ZDR进行噪声和系统误差订正后发现，订正后的ZDR得到改善。这些初步分析和结果对S波段双偏振雷达数据的使用有一定的参考意义。Abstract: At present, there are five S-band polarimetric weather radars operating in Guangdong province. Due to the technical limitation of the current polarimetric weather radars, the raw polarimetric variables are still unstable, andthe data availability and the main influencing factors must be analyzed in order to ensure the reliability of radar products. Based on the continuous observation data of the dual polarization radar in Guangzhoufrom July to August in 2016, the effects of signal-to-noise ratios (SNR) on cross-correlation coefficients at zero lag (ρHV (0)) and differential reflectivity (ZDR) were analyzed.The result shows that only when SNR reaches 20.0 dB or above, the radar data is credible, and the SNR threshold value of the data can be decreased to 17.0 dB after noise correction. The relation between reflectivity (ZH) and ZDR after noise correction was also analyzed and compared with the fitting results of the raindrops spectrum and the simulated data. The result shows that the measured value of ZDR of a polarimetricradar in Guangzhou is less than both of the fitting results and the simulated data. After the micro-raindrop method index was adjustedaccording to the climatic characteristics of Guangdong, the system bias of ZDR, initial differential phase(ΦDP(0)) with the different azimuth and time were further analyzed. It is found that ZDR fluctuates between -0.29 dB and -0.22 dB with the azimuth, the average deviation is -0.09 dB after excluding theblockage; and ΦDP(0) fluctuates about 4 ° with the azimuth, and the system biases of ZDR, ΦDP(0) fluctuatewith time obviously. In the end, the ZDR was corrected in terms of noise and system biases, and the result shows the quality of ZDR has been improved. These preliminary results are useful for polarization radar data applications.
-
Key words:
- quality of data /
- characteristics of system bias /
- micro-raindrop method /
- S-Band Polarimetric Radar /
- ZDR /
- SNR
-
表 1 广州双偏振雷达主要参数
雷达构件 主要参量 参数 天线 直径（旋转抛物面） 8.5 m 增益 ≥44 dB 波束宽度 0.95 ° 工作频率 2 885 MHz 峰值功率 ≥650 KW 发射机 脉冲宽度 1.57 μs, 4.7 μs 脉冲重复频率 322~1 304 Hz 工作模式 双发双收 接收机 最小可测功率 ≤-109 dBm（1.57 μs） ≤-114 dBm（4.7 μs） 噪声系数 ≤4 dB 动态范围 ≥85 dB 距离分辨率 250 m/1 000m 观测精度 强度Z ≤1 dB 速度V/谱宽W ≤1 m/s 差分反射率因子ZDR ≤0.2 dB 差分传播相移ΦDP ≤2 ° 差分传播相移率KDP ≤0.2 °/km 相关系数ρHV(0) ≤0.001 
下载: 导出CSV
表 2 ZDR-ZH拟合系数
系数 系数a 系数b 系数c 观测值拟合系数 0.001 0 -0.025 7 0.159 7 雨滴谱拟合系数 0.000 6 0.016 9 -0.163 3
下载: 导出CSV
-
[1] RYZHKOV A V, GIANGRANDE S E, SCHUUR T J. Rainfall estimation with a polarimetric prototype of WSR-88D[J]. J Appl Meteor, 2005, 44: 502-515. [2] 吴林林. 利用雨滴谱对移动双偏振雷达进行质量控制及降水估测[D]. 中国气象科学研究院. 2014. [3] 高玉芳, 陈耀登, DAVID Gochis, 等. JOPLE算法结合双偏振雷达在不同降水过程中的测雨效果分析[J].热带气象学报, 2014, 30(2): 361-367. [4] 吴林林, 刘黎平, 袁野, 等. C波段车载双偏振雷达ZDR资料处理方法研究[J].高原气象, 2015, 34(1): 279-287. [5] LIU L P, HU Z Q, FANG W G, et al. Calibration and data qualitya analysis with moblie C-band polarimetric radar[J]. Acta Meteor Sinica, 2010, 24(4): 501-509. [6] 魏洪峰, 薛震刚.双偏振多普勒天气雷达差分反射率因子的测量误差[J].气象科技, 2008, 36(2): 223-227. [7] 曹俊武, 胡志群, 陈晓辉, 等.影响双偏振雷达相位探测精度的分析[J].高原气象, 2011, 30(3): 817-822. [8] HU Z Q, LIU L P, WANG L R. A quality assurance procedure and evaluation of rainfall estimates for C-Band polarimetricradar[J]. Adv Atmos Sci, 2012, 29(1): 144-156. [9] FRIEDRICH K, HAGEN M, EINFALT.A Quality control concept for radar reflectivity, polarimetric parameters, and Doppler velocity[J]. J Atmos Ocean Technol, 2006, 23: 865-887. [10] 杜牧云, 刘黎平, 胡志群, 等.双线偏振雷达差分反射率因子系统误差订正[J].高原气象, 2013, 32(4): 1 174-1 185. [11] 胡志群, 刘黎平, 吴林林, 等. C波段偏振雷达几种系统误差标定方法对比分析[J].高原气象, 2014, 33(1): 221-231. [12] BEARD K V. Terminal velocity adjustment for cloud and precipitation drops aloft[J]. J Atmos Sci, 1977, 34: 1 293-1 298. [13] PRUPPAEHERHR, BEARD K V. A wind tunnel investigation of the internal circualtlonand shape of water drops falling at terminal velocity in air[J]. Q J Roy Meteor Soc, 1970, 96: 247-256. [14] BRINGI V N, CHANDRASEKAR V. Polarimetric doppler weather radar: principles and applications[M]. London: Cambridge University Press, 2001, 636. [15] 杜牧云, 刘黎平, 胡志群, 等.双线偏振多普勒雷达资料质量分析[J].气象学报, 2013, 71(1): 146-158. [16] BARBER P, YEH C. Scattering of electromagnetic wave by arbitrarily shaped dielectric bodies[J]. Appl Opt, 1975, 14(12): 2 864-2 872. [17] ATLAS D, ULBRICH C W. Path and area integrated rainfall measurement by microwave in the 1-3cm band[J]. J Appl Meter, 1977, 16(12): 1322-1331. [18] GUNN R, KINZER G D. The terminal velocity of fall for water droplets in stagnant air[J]. J Meteor, 1949, 6: 243-248. [19] 徐道生, 张艳霞, 张诚忠, 等.华南区域高分辨率模式中不同雷达回波反演技术方案的比较试验[J].热带气象学报, 2016, 32(1): 9-18. [20] 廖菲, 邓华, 侯灵.降水条件下风廓线雷达数据质量分析及处理[J].热带气象学报, 2016, 32(5): 588-596. -
点击查看大图
图(6) / 表(2)
计量
- 文章访问数: 1304
- HTML全文浏览量: 27
- PDF下载量: 967
- 被引次数: 0
粤公网安备 4401069904700003号