用C波段双线偏振雷达研究冰雹云

本文计算了不同相态、不同形状的降水粒子对5.6cm,10.7cm雷达波的散射特性,并利用降水粒子散射特性及云雨雷达回波的Z_(DR)特征并结合地面降雹情况,分析并解释了1990年8月9日和8月30日甘肃省平凉两次雹暴过程的雷达RHI资料.我们推测:Z_(DR)值为负值的区域相应于降雹区,ZDR负值与大扁冰雹和小锥状冰雹关系密切;而雨区Z_(DR)具有较大正值,雨区大于5dB的Z_(DR)由直径D>0.5cm的雨滴所致.利用冰雹区和雨区Z_(DR)信息的不同可能识别降水粒子的相态.C波段双线偏振雷达和10cm波长雷达相比有独到之处:雨区Z_(DR)值较大,而冰雹区Z_(DR)值又较小,这更有利于研究云雨相态和空间结构.可以预期双线偏振雷达对防雹工作及云物理研究工作是有很大帮助的.

Study of Hail with C B and Dual Linear Polarization Radar

This paper presents the calculations of the scattering properties of hydrometeors with different shapes and phases. Based on these properties and ZDR features of rain and clond echos, the dual linear polarization radar RHI data observed during hailstorm processes on August 9 and August 30, 1990 are analysed . We deduced that the area with negative ZDR values corresponded to hail shafts where may appear large oblate hailstones and small conical hailstones, and the area with great positive Z D R values corresponded to raining area . The Z D R greater than 5dB was caused by huge raindrops (D>0.5cm). It is possible to detect the presence of hail using ZDR as a criterion. Compared with a S-band radar, the C-band dual linear polarization radar is unique in several aspects : the Z DR values are larger in raining area and smaller and negative in hail shooting area , which are useful for the study of microphysics and spatial structure of storms. The dual linear polarization radar will be impartant to cloud physics and weather modification .