毫米波雷达资料融化层亮带特征的分析及识别

Analysis of the Characters of Melting Layer of Cloud Radar Data and Its Identification

云的融化层亮带位置、厚度及其回波强度的垂直结构变化信息对于云和降水物理研究、人工影响天气指挥和效果评估,数值模拟云参数化均有非常重要的意义。为了了解云层融化层高度的精确位置,根据云雷达在广东、河北、吉林等不同云过程总计456个例分析(其中确认融化层明显个例34次),系统分析云雷达探测到融化层亮带宏观参量的统计情况,包括融化层厚度、反射率因子在融化层强度变化、退偏振因子在融化层的强度变化,并提出了一种结合垂直探测的云雷达探测到的雷达反射率因子(R)和退偏振因子(Ldr)垂直廓线数据,根据参量在融化层附近显著变化特性,识别零度层亮带高度和厚度的算法。同时选取个例对应观测时刻探空资料观测的0°层高度进行对比,反演的融化层高度等参数同实际情况比较接近,位于探空资料观测的0°层下方,而且退偏振因子对融化层的敏感程度大于反射率因子。

As we well know that, it is meaningful if we obtain the exact altitude of the melting layer, its depth and much more other information about cloud, and we could utilize them in retrieving cloud micro- physics, weather modification, cloud parameterization of numerical modeling and its evaluation. In order to acquaint the definite location of the metling layer in a cloud, in this paper, first of all we have analyzed 456 cases observed at Guangdong, Hebei and Jilin by our could-radar during recent three years, and there are 34 cases in which appear notable metling features. Secondly we take account of the macroscopic param- eters ~ characteristics, such as the depth of melting layer, the variation of the radar reflectivity at the melt- ing layer. And then one method is proposed which makes use of the vertical profile of radar reflectivity and linear depolarization ratio to identify the altitude and depth of the melting layer. Afterwards, we select and use the rawinsonde data at the same time for the same case to make comparative experiments, which showthat the results of the tw 0°line of the rawinsonde flectivity to the melting 1° kinds of data are very closer, the result by inversion method is nearly below the data, and the linear depolarization ratio indicates more sensitive than the radar re- ayer.