利用第二类正则变换方法反演COSMIC掩星探测数据

Retrieving COSMIC radio occultation data by second canonical transformation

为了验证第二类正则变换（CT2）方法反演折射率的精度,选取2007-2009年1月和7月的气象、电离层和气候观测系统星座（COSMIC）附加相位和振幅数据,利用CT2方法处理得到折射率,并与利用全谱反演（FSI）方法得到的COSMIC折射率数据、欧洲中期天气预报中心（ECMWF）分析资料折射率进行对比。结果表明,CT2方法反演的折射率、COSMIC折射率以及ECMWF分析资料折射率的平均偏差在1~40km均不超过1%;在1~15km,CT2方法和FSI方法反演的折射率与ECMWF分析资料折射率的平均偏差均在1%以内;CT2方法与ECMWF分析资料折射率偏差的标准差小于FSI方法的。总的来说,CT2方法和FSI方法都具有很高的反演精度,但随着水汽含量的增加,CT2方法和FSI方法的反演精度会降低,并且CT2方法反演的不确定性小于FSI方法。

In order to validate the second canonical transformation（CT2）based inversion precision.,in the present paper,excess phase and amplitude data in January and July from 2007 to 2009from constellation observing system for meteorology,ionosphere and climate（COSMIC）were processed by the CT2 method,and refractivity profiles were obtained,and compared with the refractivity data from COSMIC data products retrieved by the full spectrum inversion（FSI）method and ECMWF analysis.It turns out that the average biases of the retrieved refractivity between the CT2 method and COSMIC and between the CT2 method and ECMWF analysis don＇t exceed 1%in the 1-40 km height interval.In addition,the results indicate that the average biases of the retrieved refractivity between the CT2 method and ECMWF analysis and between the FSI method and ECMWF analysis do not exceed 1%in the 1-15 km height interval;Finally it is found that the standard deviation of the difference between CT2 derived refractivity and ECMWF analysis refractivity is smaller than the FSI derived refractivity and ECMWF analysis refractivity.In a word,the CT2 method has a high inversion accuracy as well as the FSI method,but with increasing water vapor content,the inversion accuracy of the both methods reduces.Besides,the CT2 method has smaller inversion uncertainty than the FSI method.