Simulation Of Local Atmospheric Radiative Transmission

The atmosphere is a very complex system,which varies greatly in different regions,environments,time and other conditions.Atmospheric radiation transmission is one of the basic physical processes of the atmosphere,and it is a key process in ground-based calibration,remote sensing inversion and verification.In the thermal infrared band,atmospheric radiation transmission is affected by the profiles of atmospheric temperature,humidity,and pressure.Accurate atmospheric radiation transmission simulation is crucial for the correction of thermal infrared data,and this simulation relies on the acquisition and use of high-precision atmospheric profiles and atmospheric radiation transmission models.The standard atmospheric model of the traditional atmospheric radiative transfer model can only describe large-scale regional atmospheric characteristics,and it is difficult to accurately characterize the dynamic changes of the local atmosphere.Therefore,how to obtain and evaluate the atmospheric profile and build a local atmospheric model that is more in line with the actual atmospheric conditions is an urgent problem.In this study,the UWYO(the University of Wyoming)ground-based sounding atmospheric profile is used as reference data to comprehensively evaluate the accuracy of 7 atmospheric profiles from different sources,which are: the MODerate-resolution Imaging Spectroradiomete atmospheric profile product(MYD07),the Atmospheric Infrared Sounder atmospheric profile product(AIRS),the European Centre for Medium-range Weather Forecasts(ECMWF),the Modern-Era Retrospective analysis for Research and Applications,Version 2(MERRA2),the National Centers for Environmental Prediction(NCEP)/Global Forecasting System(GFS)NCEP/GFS,NCEP/Final Operational Global Analysis(FNL),and NCEP/Department of Energy(DOE).At the same time,based on China's five major climatic zones,and using data from the atmospheric profiles of 86 UWYO sounding stations in China from 2000 to 2019 for 20 years,a local atmospheric model that is more in line with China's atmospheric conditions was constructed.The main research conclusions are as follows:(1)Using UWYO atmospheric profile as reference data,MYD07 atmospheric profile has the worst accuracy.The largest discrepancy of the vertical distribution of air temperature and dew point temperature profiles was observed between the MYD07 and UWYO profiles.The worst accuracy of atmospheric parameters was obtained for the MYD07 profile,with RMSE values of approximately 0.06,0.5 W/m2/sr/?m,0.7 W/m2/sr/?m,and 0.4 g/cm2 for atmospheric transmittance,upwelling radiance,downwelling radiance,and WVC,respectively.(2)Compared with the UWYO profile,the RMSE values(approximately 0.5 K)of the retrieved LST that used the ECMWF,MERRA2,NCEP/GFS,and NCEP/FNL profiles were smaller than those(larger than 0.8 K)that used the MYD07,AIRS,and NCEP/DOE profiles.Compared with the in situ LST measurements that were collected at the Hailar,Urad Front Banner,and Wuhai sites,the RMSE values of the retrieved LST that used the ECMWF,MERRA2,NCEP/GFS,and NCEP/FNL profiles were approximately 1.0 K.The worse accuracy of the retrieved LST was obtained for the NCEP/DOE profile,with an RMSE value of approximately 1.5 K.In general,ECMWF,MERRA2,NCEP/GFS and NCEP/FNL atmospheric profiles can calculate more accurate atmospheric parameters.(3)The results of local atmospheric model fitting show that the parameter fitting results of China's five major climatic regions are generally consistent with their respective climate characteristics.The tropical monsoon climate zone showed the best fitting accuracy in the four seasons of spring,summer,autumn,and winter.The fitted RMSE values of the air pressure profile are all less than 0.01 h Pa,the temperature profile is basically stable near 295 K at 1 km,and the water vapor profile has a significant seasonal difference,and the water vapor difference reaches 7 g/kg at 1 km.And this is exactly in line with its climatic characteristics of high temperature and obvious dry and wet seasons throughout the year.It also shows that the local atmospheric model constructed in this paper is basically in line with China's actual situation.