GPM/DPR雷达反演三参数滴谱廓线方法研究

GPM Core Observatory which carried the first space-borne Ku/Ka-band Dual-frequency Precipitation Radar (DPR) has been successfully launched on Feb, 27, 2014. It will provide measurements of microphysical properties and vertical structure information using active DPR radar over a broad spectral range. The surface reference technique (SRT) is employed for estimating path integrated attenuation (PIA) due to its shorter wavelength. However, the SRT works not so well over the land as over the ocean. In this proposed project, the ground-based measurement of near surface precipitation is suggested to replace the normalized radar cross section (NRCS) in the SRT for better estimation of drop size distribution profile. And the retrieval algorithm for three parameter drop size distribution profile will also develop with the help of ground based radar.

载有双波长测雨雷达DPR的全球降水测量项目GPM的核心卫星已经成功发射，在为全球提供更大范围、更好质量降水数据的同时，还可以提供二参数的滴谱廓线产品，为云降水物理尤其是雨滴谱廓线研究提供了新的视角和途径。然而，受星载雷达波长较短的限制，如何订正衰减一直是个挑战，尤其在陆面，表面参考技术SRT估计路径总衰减量PIA并不理想，直接制约了陆面滴谱廓线反演的精度，为了提高DPR陆面反演滴谱廓线的精度，本项目拟采用地基测量近地层降水散射特性的方法，为DPR雷达提供远端无衰减的参考值，以期提高DPR雷达反演滴谱廓线的精度；在此基础上，借助地面垂直指向雷达或体积扫描雷达，进一步研究星地雷达联合组成三波长雷达反演三参数滴谱廓线的方法，为滴谱廓线研究创造条件。

将测雨雷达架设在卫星上是未来全球降水测量的发展趋势，降水衰减尤其是陆面降水衰减是星载雷达面临的主要挑战，项目在研究分析陆面标准化雷达截面特征基础上，提出相似廓线法，为陆面衰减订正提供了一条新的途径，对比评估表明该方法是合理有效的，有一定的实际应用价值。在星地雷达联合反演雨滴谱方面，借助地面测雨雷达观测和雷达仿真软件Quickbeam，提出一种雨滴谱反演中双值问题的解决方法，与地面雨滴谱仪观测对比表明该方法是有效可行的。