基于高分辨率高程数据统计分析新一代天气雷达组网的地形遮挡影响

Statistical analysis of terrain blockage impacts on the CINRAD network based on DEM data

新一代天气雷达由于受到地形限制产生波束遮挡导致波束能量衰减,从而造成雷达探测回波强度偏弱、雷达定量估测降水结果失真,因此对于雷达波束遮挡情况的统计和分析是一项重要的基础研究工作。利用SRTM(Shuttle Radar Topography Mission)数字高程数据对中国目前业务运行的212部新一代天气雷达波束遮挡情况进行模拟计算分析。计算结果包括雷达单站遮蔽角、VCP21模式0.5°、1.5°、2.4°、3.4°、4.3°仰角波束遮挡率、混合扫描及分区混合扫描波束遮挡率、雷达单站探测范围覆盖情况;计算并绘制全国天气雷达组网遮挡率拼图,统计全国天气雷达组网遮挡情况;利用2019年8月广东省11部天气雷达基数据对比验证单站及组网遮挡计算结果。结果表明雷达组网探测面积覆盖率超过70%,整体覆盖效果较好,遮挡计算结果与实际数据对比验证结果高度一致,对雷达数据订正、降水估测等产品具有正贡献。

The weather radar beam energy is usually attenuation due to the terrain blockage,which will lead to lower intensity of radar reflectivity and unrealistic radar quantitative precipitation estimation(QPE).Therefore,it is an important basic work to statistics and analyze of radar beam blockage.This paper simulates and analyzes the observational environments of the 212 operational CINRAD radars using Shuttle Radar Topography Mission(SRTM)digital elevation data.The shielding angle,the Beam Blockage Percentages(BBPs)at 0.5°,1.5°,2.4°,3.4°and 4.3°elevation angles in VCP21 mode,the BBPs in hybrid scan mode and subarea hybrid scan mode,and the effective coverage of observational range are first calculated for each weather radar.The terrain blockage effect on the CINRAD radar network is then analyzed statistically and the BBP mosaic image of the CINRAD radar network is mapped.The 11 CINRAD radars base data in Guangdong province in August 2019 are used to verify the analysis result of single station and radar network beam blockage.The results indicate that the effective observational coverage of the CINRAD radar network region exceeds 70%.The analysis results of BBPs are highly consistent with the actual data,and have positive contributions to radar reflectivity correction,QPE correction and other products.