COSMIC-2 Occultation Atmospheric Profile Inversion Quality Assessment And Boundary Layer Height Inversion Method Research

GNSS Radio Occultation(GNSS-RO)detection technology makes up for the deficiency of traditional observing methods in meteorological field,which has been widely used in the detection and research of global atmosphere.However,there is still a problem of data quality degradation due to the increase of water vapor,which limits the application of RO data.COSMIC-2 Radio Occultation Mission uses a new generation of payload for observation,which has high signal-to-noise ratio and can greatly improve the quantity and quality of data theoretically.Therefore,it is particularly important to quantitatively analyze the accuracy of retrieval data to ensure the quality of subsequent application products.This paper is divided into two parts.In the first part,comparison is carried out to verify the atmospheric refractivity,temperature and relative humidity profiles,which are calculated by Radio Occultation Processing Package(ROPP)based on COSMIC-2 excess phase data.The results are evaluated with the radiosonde data by latitude and season,especially the accuracy of profile samples in low latitude zone and low troposphere.The experimental results show that the atmospheric profiles retrieved from COSMIC-2 data have high precision,in which standard deviations of relative biases of atmospheric refractivity are 1.5% ~ 4.3%,and root mean squared errors of atmospheric temperature and relative humidity are 1.3 ~ 2.2K and 10% ~ 15%,respectively.Compared with the wet Pf2 products of COSMIC-2,the precision of retrieved refractivity and temperature in some height layers is better,and the precision of retrieved relative humidity in general is better.The precision of samples in low latitude area is better than that in middle latitude area.The seasonal difference is not obvious.It shows that COSMIC-2RO data still maintain high accuracy in the low latitude zone,low troposphere and summer samples with more water vapor,which has great application value.In the second part,the atmospheric boundary layer height(ABLH)is retrieved by COSMIC-2 refractivity data,using wavelet covariance transform(WCT)method.By defining the significance parameter,the significant boundary layer tops in the samples are selected for statistics.The average deviation is-0.09 km,the root mean square error is 0.66 km and the correlation coefficient is 0.667.Applying COSMIC-2 retrieval refractivity data to the study of distribution and variation characteristics of ABLH.It is found that COSMIC-2 RO data can better characterize the distribution and variation characteristics of global ABLH,and show the obvious distribution difference and daily variation characteristics of ABLH between land and ocean.These obvious differences and characteristics are compared with the current height of global atmospheric boundary layer The results are consistent,which shows that the COSMIC-2 RO data is accurate and reliable in the study of global ABLH retrieval.