中国新一代天气雷达很多站址位于地形复杂的山区, 附近地物会对雷达波束造成遮挡。以浙江衢州雷达为例, 统计该站附近多年探空资料得到雷达波束传播路径分布, 并分别采用30 m和90 m分辨率地形数据和两种雷达库长内地形数据处理方法, 模拟了雷达波束遮挡。通过与雷达实际观测的回波分布概率POD对比, 检验了雷达波束遮挡模拟结果的可靠性, 分析了不同地形数据分辨率和两种处理方法模拟结果的差异。结果表明, 一般情况下, 标准大气条件假定足以满足衢州雷达波束遮挡计算精度要求; 模拟波束遮挡与实际观测一致性较好; 对于近距离遮挡源, 不同地形数据分辨率及其处理方法的模拟结果区别较明显, 地形数据分辨率越高、分段法模拟的结果与实际观测越一致, 而对于远距离遮挡源则无明显区别。鉴于模拟波束遮档的可靠性, 针对部分雷达站址不够准确或有偏差的现象, 提出通过分析实测回波分布与模拟波束遮挡间的相关性来检验并修正雷达位置的方法, 经位置修正后金华雷达模拟的波束遮挡与实测回波分布一致性较好。
Many sites of China new generation weather radar network locate in mountainous regions, where terrain near the radar often causes beam blockage.As an example, actual beam propagation path is calculated based on years of sounding data for Quzhou radar, then using the calculated local beam propagation path, beam blockage is simulated by two processing methods with DEM of different resolutions, 30 m and 90 m.Simulated beam blockage results were verified by contrasting with the probabilityof detection(POD) of radar. The results show that: Normally, the simulated beam blockage agreements with radar observation well; the resolution of DEM and the processing method affects the accuracy of simulation beam blockage significantly if the obstacle is close enough to the radar, the sectionalized-method, the higher resolution of DEM, the more consistent with each other they are. But such is not significant for remoter obstacles. Since the simulated beam blockage is reliable, a method of checking and correcting radar position according to the correlation between it and POD is proposed to resolve the problem of biased or inaccurate position for some radars. Jinhua radar's simulated beam blockage matches actual reflectivity distribution very well after correcting position by this method.
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