超低仰角扫描改进高山雷达降水估测

Precipitation Estimation of Mountain Weather Radar Improved Using Ultra-Low Elevation

利用2004年5月云南大暴雨过程的26次昆明雷达超低仰角对比观测体扫资料,分析了昆明雷达0°和0.5°仰角数据以及对比了定量估测降水的情况。结果表明:0°仰角探测到的降水分布范围更大;与0.5°仰角相比,通过定量计算,探测降水范围能提高约9.96%,估测的降水总量约为11.6%。从探测到的降水量和范围来看,0°仰角较0.5°仰角能明显改善高山雷达远距离降水探测效果。对比分析0°仰角和0.5°仰角数据表明,对于高山雷达,如果周围地形不高,采用0°仰角估计雨量更合理。利用德宏高山雷达进一步探测局部区域降水时,对比两个不同仰角的回波强度与雨量计观测雨量的相关性,除得到与昆明雷达相似的结果外,0°仰角时反射率因子与雨量计雨量的相关性较好,说明0°仰角对降水的探测能力较高。另外,雷达反演降水的垂直和水平结构均反映出云南高原地区降水分布存在较强不均匀性。结果表明,高山雷达排除地物等因素影响后,合理选用超低仰角探测可进一步提高雷达探测降水的能力,提高范围在2%～9.96%之间。这一结果对于雷达观测模式的优化有一定的参考价值。

Based on 26 times radar data at ultra-low elevation during the process of heavy rainstorm in Kunming in May 2004,the value of radar data at 0° elevation in quantitative precipitation estimation（QPE） was discussed using the radar data at 0° and 0.5° elevations.The results showed that： The ability of detection precipitation at far from mountain weather radar was weaker at 0.5° elevation than that of 0° elevation.There was no ground clutter at 0° elevation in Kunming radar by comparing with radar data at 0° and 0.5° elevations.0° elevation can improve the ability of detection precipitation at far from mountain weather radar from amount of precipitation and detection range.Precipitation range/amount at 0° elevation was larger 9.96%（about 28.147 km2）/11.6% than that of 0.5° elevation.The precipitation process dominated by stable stratiform echoes about 25 dBz,which reflected inhomogeneous precipitation distribution in Yunnan from vertical and horizontal structures of precipitation.It was showed that ultra-low elevation in mountain weather radar could improve the detection ability after eliminating ground clutter.