利用低仰角扫描改进高山雷达低层回波探测能力浅析

Improved Detection Using Negative Elevation Angles for Mountaintop Radars

应用昆明高山新一代天气雷达探测大范围暴雨个例的0°仰角资料,与我国高山雷达目前采用最低仰角为0.5°扫描模式(VCP11或VCP21)的回波分布情况进行了对比分析。结果表明:在雷达警戒区域,0°较0.5°仰角能更早地发现过程的降水云系;0°或负仰角能明显提高高山雷达远距离回波探测效果;低仰角(文中指低于0.5°仰角)可弥补常规业务扫描模式下高山雷达探测低层回波能力不足的问题。对另一次文山雷达对冰雹过程的探测分析,可见低仰角扫描模式对强对流天气也能获得较好的低层探测效果。又通过实验获得云南另外4部高山雷达的0°仰角及负仰角晴空资料,分析了高山雷达晴空资料的0°及负仰角低层回波资料质量。发现受周围山脉影响,不同高山雷达最佳探测低仰角是不同的,实际业务工作中应根据当地地形的具体情况选取恰当的低仰角。

VCP11 or VCP21 model lowest switched on 0.5° elevation angle is being applied in mountaintop radar scanning ways in China now. Contrast analyses are made between the two models and new generation radar of Kunming switched on 0° elevation angle through practical detection of a heavy rainstorm case. The preliminary result shows that some mountaintop radars can discover precipitating process earlier on 0° elevation angle than on 0.5° elevation angle. Remote detection effect of precipitation by mountaintop radar is obviously strengthened on 0° elevation angle and negative elevation angle. The insufficient of detection ability of mountaintop radar for lowlevel radar echo in routine scan way can be remedied by being switched on negative elevation an- gle. By using the data obtained from other 4 mountaintop radars of Yunnan in experiment, quality comparative analysis of low-level echo detection is made between the clear-day data obtained from mountaintop radar and data of mountaintop radar switched on low elevation angle and negative elevation angle. The results shows that the best low elevation detection angle of mountaintop radar is different owing to the influence of surrounding mountains. The suitable low elevation angle in practical work should be selected according to related topography.