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毫米波测云雷达探测云目标时,电磁波除了受到云目标衰减之外,还受到大气传输中氧气以及水汽的衰减,电磁波的衰减导致雷达观测到的回波强度小于云目标的实际回波强度,这种误差将影响云内结构的反演。因此,为了使毫米波测云雷达的探测数据正确地反演出云目标的宏观物理特征,必须对进行毫米波测云雷达工作频率下气象目标物的衰减进行订正。主要利用逐库衰减订正算法以及分级逐库衰减订正算法对英国Chilbolton观测场94 GHz毫米波测云雷达的一次降水云观测结果进行了垂直方向的大气衰减订正研究,并比较逐库衰减订正算法以及分级逐库衰减订正算法间的反演差异。同时,利用国际电信联盟ITU-RP.676-10建议书中氧气以及水汽衰减订正公式进行了毫米波测云雷达探测数据的二次订正。分析和对比结果表明,衰减系数的变化对于云目标的宏观物理特征反演有着明显的影响,并且分级逐库衰减订正法的订正效果强于逐库衰减订正法。
In addition to the cloud target attenuation, the electromagnetic wave is also attenuated by oxygen and water vapor in the atmospheric transmission when the millimeter-wave detection cloud radar detects the cloud target. The attenuation of the electromagnetic wave causes the echo intensity observed by the radar to be smaller than the actual echo intensity of the cloud target, This error will affect the inversion of cloud structure. Therefore, in order to correctly detect the macroscopic physical characteristics of the cloud targets, the attenuation of the meteorological targets at the working frequency of the millimeter-wave cloud-detecting radar must be corrected. The correction of atmospheric attenuation in the vertical direction was mainly carried out by using the reservoir-by-reservoir attenuator correction algorithm and the hierarchical reservoir-by-reservoir attenuation correction algorithm for the first precipitation cloud observation of the 94 GHz millimeter-wave cloud detection radar at Chilbolton Observatory in the United Kingdom. Inversion of Correction between Corrected Algorithms of Graded and Library Attenuation. In the meantime, the second correction of the data of millimeter wave detection cloud radar is made by using the revised formulas of oxygen and water vapor attenuation in ITU-RP. 676-10 of the International Telecommunication Union. The results of analysis and comparison show that the change of attenuation coefficient has a significant effect on the retrieval of macroscopic physical features of cloud targets, and the correction effect of step by step attenuated correction method is stronger than the one by one.