以中国气象局大气探测重点开放实验室的X波段双线偏振雷达为平台， 利用2010年夏季成都晴空与降水条件下雷达低仰角的回波数据， 统计分析了能够与气象回波进行区分的地物回波双偏振参量特征。结果表明， 多数地物回波相关系数<0.85， 而多数降水回波相关系数>0.90； 地物回波差分反射率呈随机极化特点， 强度分布覆盖在-20~20 dB之间， 且均值集中于0 dB； 降水回波差分反射率集中分布于-3~6 dB之间。地物回波的比相差分布覆盖了整个π区间， 而气象回波则集中在-6~6°·km-1之间， KDP区分二者差异效果明显。在识别地物回波过程中， 偏振参量的影响权重依次为KDP>ZDR>|ρhv|。同时, 统计了特定阈值条件下地物回波与天气回波的发生概率， 在此基础上实现了模糊逻辑识别地物回波\.利用地物回波ZDR统计均值和4 h时间变化的均方根值， 得到雷达系统偏差为-2.15 dB， 其短时变化的均方根为0.28 dB。
X-band dual polarization radar is taken as the test platform at the key laboratory of atmospheric sounding of China Meteorological Administration. Statistical characteristics of dual-polarization parameters of ground clutter that differentiated from weather echoes were analyzed by radar echoes with low elevation angle in the clear and precipitation condition of Chengdu in summer of 2010. The results show that the correlation coefficients of most ground clutter are less than 0.85, while the correlation coefficients of most weather echoes are greater than 0.90. The differential reflectivity of ground clutter is randomly polarized, the intensity distribution covers between -20~20 dB, and the mean concentration is 0 dB and the weather echoes are concentrated between -3~6 dB; The KDP of ground clutter covers the entire π interval, and the KDP of weather echoes are concentrated from -6 to 6°·km-1. Test data show that the KDP distinguishes the difference between clutter and weather echoes obviously. The important parameters of identifying ground clutter are KDP, ZDR and ρhv. Base on the occurrence possibility of polarized parameters about clutter and weather echoes, fuzzy logic is utilized to identify ground clutter. Furthermore, the calibration of ZDR is taken with ground clutter. The standard variance of ZDR bias is -2.15 dB, and the short-term mean of ZDR bias is 0.28 dB within four hours.
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