多普勒天气雷达组网拼图有效数据区域分析  

The Valid Mosaic Data Region of the CINRAD Network

作　　者：杨洪平[1,2] 张沛源[1] 程明虎[1] 李柏[2] 熊毅[3] 高玉春[2] 陈大任[2] 

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081 [2]中国气象局气象探测中心,北京100081 [3]中国气象局监测网络司,北京100081

出　　处：《应用气象学报》2009年第1期47-55,共9页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(40375006);武汉暴雨研究所开放基金课题(IHR20053)共同资助

摘　　要：在正常情况下,由于天线仰角和地球曲率原因,雷达波束位置在远距离处要比近距离处高。当雷达电磁波能量被部分阻挡时,回波强度观测值低估;被完全挡住时,探测不到地物后的目标。该文利用高分辨率地形高程数据计算波束阻挡率,确定组网拼图有效数据区域以及波束部分阻挡时的回波强度订正方法。根据业务观测模式VCP11及VCP12的14个仰角值,在标准大气假定下,对湖南、江西、浙江、福建、广东、广西和海南已建多普勒天气雷达组网的数据有效区域进行计算,绘制出海拔1500 m,3000 m和6000 m高度上有效区域图。分析结果表明:CAPPI数据有效范围比等射束高度图更能反映出多普勒天气雷达业务观测范围;若采用VCP12模式观测,与采用VCP11或VCP21模式观测相比,不仅增加低层探测密度,而且可扩大雷达实际探测距离,其回波数据更适合于组网拼图。Along the normal propagation path, the radar ray becomes higher and higher due to effects of the earth curvature and positive elevation angle of transmitter. Actually, radar waves are often blocked as they propagate through mountain areas. When radar beam has occultation, its real sample volume will be smaller than that of zero occultation, echo intensity of targets will be underestimated if it is partial occultation, and targets will he totally missed if complete occultation occurs. It is common practice now to use occultation rate for beam occultation correction. Assuming that radar waves propagate in standard atmosphere, occultation rates of radar beam herein are calculated with the high resolution digital elevation map data, and are utilized to analyze the valid mosaic data region of netted radars and to assess the beam occultation correction. Test shows that echo will be severely underestimated and waves can be considered to be com- pletely blocked when the occultation rate is larger than 55%. Based on that, in terms of the 14 elevation angles of two Volume Coverage Pattern modes, VCP11 and VCP12, the real detecting ranges of netted radars are obtained. The netted radars include the local CINRAD in Hunan, Jiangxi, Zhejiang, Fujian, Guangdong, Guangxi and Hainan provinces. Compared with the equivalent beam range at the same height, the valid data range of CAPPI is more suitable to represent the real detection range. Among the valid mosaic date regions at the height of 1500 m, 3000 m and 6000 m above the sea level, the largest blank area can be seen in the graph of 1500 m height, but can hardly be seen in that of 6000 m height. In the overlapping area of 6000 m height, most common grids can be detected by three radars or more, some by the maximum of six. Observations in VCP12,compared with that in VCP11 or in VCP21, are more useful to construct mosaic data not only because of its dense vertical sample in low elevation but also its larger valid data range in mountain areas. According to the definition formula o

关 键 词：多普勒天气雷达 组网拼图 有效数据区域 

分 类 号：P412.25[天文地球—大气科学及气象学]