Relationship between cloud characteristics and radar reflectivity based on aircraft and cloud radar co-observations
Relationship between cloud characteristics and radar reflectivity based on aircraft and cloud radar co-observations
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DOI：
10.1007/s00376-013-2090-7
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发表时间：
2013-01
影响因子：
5.8
通讯作者：
Rong Zong;Liping Liu;Yan Yin
中科院分区：
文献类型：
--
作者：
Rong Zong;Liping Liu;Yan Yin
利用飞机和云雷达在吉林伊通进行的联合观测，研究了中国所在地区的云特征。飞机提供云滴大小分布的现场测量，而毫米波云层雷达垂直扫描飞机穿透的同一片云。从飞机测量计算的反射率因子与同时的雷达观测进行了详细的比较。结果表明，两种反射率在暖云中具有可比性，但在冰云中差异较大，这可能与液态水的存在有关。在水云中获得的反射率之间可接受的一致性证实，通过使用飞机数据来获得云属性是可行的，从而云雷达可以远程探测云属性。基于收集到的暖云数据集，通过分析云粒子和雨滴反射率的概率分布函数，研究了诊断细雨和云粒的反射率阈值。根据云粒和细雨资料，得到了反射率因子(Z)与云中液态水含量(LWC)的关系。与云滴相比，细雨的关系被许多散射点所模糊，因此不那么明显。但是，通过滤除反射率大、消光系数大、有效半径小的液滴尺寸分布，可以部分去除这些散射。由此可以得到云粒和细雨的Z-LWC经验关系式。
Cloud properties were investigated based on aircraft and cloud radar co-observation conducted at Yitong, Jilin, Northeast China. The aircraft providedin situmeasurements of cloud droplet size distribution, while the millimeter-wavelength cloud radar vertically scanned the same cloud that the aircraft penetrated. The reflectivity factor calculated from aircraft measurements was compared in detail with simultaneous radar observations. The results showed that the two reflectivities were comparable in warm clouds, but in ice cloud there were more differences, which were probably associated with the occurrence of liquid water. The acceptable agreement between reflectivities obtained in water cloud confirmed that it is feasible to derive cloud properties by using aircraft data, and hence for cloud radar to remotely sense cloud properties. Based on the dataset collected in warm clouds, the threshold of reflectivity to diagnose drizzle and cloud particles was studied by analyses of the probability distribution function of reflectivity from cloud particles and drizzle drops. The relationship between reflectivity factor (Z) and cloud liquid water content (LWC) was also derived from data on both cloud particles and drizzle. In comparison with cloud droplets, the relationship for drizzle was blurred by many scatter points and thus was less evident. However, these scatters could be partly removed by filtering out the drop size distribution with a large ratio of reflectivity and large extinction coefficient but small effective radius. Empirical relationships ofZ-LWC for both cloud particles and drizzle could then be derived.