星载双频云雷达的云微物理参数反演算法研究  

A study of cloud parameters retrieval algorithm for spaceborne millimeter wavelength cloud radar

作　　者：吴琼[1,2,3] 仰美霖 窦芳丽[3] 郭杨[3] 安大伟[3] 

机构地区：[1]中国科学院大气物理研究所中层大气与全球环境探测实验室,北京100029 [2]中国科学院大学,北京100049 [3]国家卫星气象中心,北京100081 [4]中国气象局北京城市气象研究所,北京100089

出　　处：《气象学报》2018年第1期160-168,共9页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(41475030;61527805)

摘　　要：使用星载雷达模拟器输出的模拟数据,为星载双频云雷达选择了最佳的频点组合,并开展了双频联合反演云微物理参数的算法研究。结果表明:(1)在位于大气窗口的6组频点组合中,94/220 GHz的组合对滴谱参数的微小变化较为敏感,有利于进行双频的联合反演。综合考虑不同频点的探测能力、衰减以及工业部门的制造水平后,认为94/220 GHz可以作为未来星载双频测云雷达的探测频点。(2)双频反演中最核心的双波长比(DWR)和体积中值直径(D_0)的关系与冰晶粒子密度相关。当密度随着粒子直径变化时,DWR随着D_0单调递增,当粒子密度固定不变时,DWR-D_0曲线可能会出现非单调变化,从而使得固定密度时的反演比变密度时更加复杂。(3)后向迭代的双频反演算法同样适用于94/220 GHz进行云微物理参数的反演,并且对模拟数据的反演精度较高。此外,反演精度受到系统噪声以及定标精度的影响,为了满足反演精度的要求,系统噪声和定标误差应该控制在1 dBz以内。Based on data simulated by satellite radar simulator unit,two frequencies have been chosen to study the dual-frequency retrieval algorithm of cloud microwave parameters.Results suggest that：（1）94/220 GHz is sensitive to tiny changes in drop size,which is beneficial for the retrieval of cloud radar parameters.Based on the consideration of detective ability,attenuation and manufacturing level in the industrial sector,94/220 GHz can be chosen as the detection frequency of spaceborne cloud radar in the future;（2）the relationship between dual wavelength ratio（DWR）and median volume diameter（D_0）relies on the particle density.DWR will increase with D_0 if the particle density changes with the diameter.Otherwise,DWR will fluctuate with D_0 when the particle density is a constant.Thereby the retrieval of a constant density is very difficult;（3）backward iteration retrieval algorithm of dual frequency can be applied by 94/220 GHz and the retrieval results are consistent with the true values.Furthermore,the precision of retrieval is influenced by system noise and calibration precision.Therefore,the noise and calibration precision should be controlled under 1 dBz in order to satisfy the requirement of retrieval precision.

关 键 词：星载雷达模拟器 星载云雷达 双频反演算法 冰晶密度 

分 类 号：P412.25[天文地球—大气科学及气象学]