Development Of Ground Data Calibration Software For Spaceborne Atmospheric Trace Gas Differential Absorption Spectrometer

Spaceborne atmospheric imaging spectrometer uses the pattern of atlas to obtain the geographic information of earth.It has very important applications in geomorphology,natural.disasters,weather prediction,environmental monitoring and even military.Spaceborne atmospheric trace gas differential absorption spectrometer(EMI)is a new type of spaceborne atmospheric imaging spectrometer with a spectral resolution of up to 0.5nm,with a 114 degree field of view and a detection band of 240?710nm,which is mainly used to detect the distribution and change of trace gases in the atmosphere.In order to obtain the spectral and radiative response characteristics of EMI,on-ground calibration tests are required.There are two aspects of on-ground calibration:first,spectral calibration,followed by radiometric calibration.Spectral calibration includes two aspects,center wavelength calibration and spectral resolution,in which wavelength calibration uses the characteristic spectral line method to match the feature line and pixel position,then the polynomial fitting is used to obtain the EMI spectral calibration equation,and then the central wavelength of each detection pixel determined.Fitting characteristic line with Gauss,Lorentz and Voigt function models,the half height width can be used to determine the EMI spectral resolution.Results show that Gauss function model can be used as EMI slit function.Radiometric calibration mainly includes absolute radiometric calibration and relative radiometric calibration.The basic theory of absolute radiometric calibration and relative radiometric calibration is introduced.In order to automatic processing a large number of EMI on-ground spectral calibration and radiometric calibration data,it is necessary to develop a on-ground calibration processing software.Based on this,this paper studied the development of EMI on-ground calibration software:this software uses C++ programming language,and is developed based on Microsoft's MFC(Microsoft Foundation Classes)application framework.The software framework includes EMI calibration data display function and calibration function.It displays EMI calibration data in grayscale,directory tree,spectral dimension,spatial dimension,etc.,and achieves calibration processing through interactive dialogs.For spectral calibration function,it can realize the automatic peak finding processing,complete the characteristic peak pixel pairing processing,and then obtain the spectral calibration equation based on the least square polynomial fitting.At the same time,the spectral resolution can be calculated by the improved Gauss algorithm.For the radiometric calibration,the effective data segment of the field of view can be identified automatically,and the effective data of each field of view can be extracted and stitching into the full field of view data.Using this software to display EMI calibration data,and to process the calibration data.The results of spectral calibration and radiation calibration are analyzed.The results show that the software runs well,the operation is convenient,the data is reliable,and the rapid spectral calibration and radiation calibration can be realized.At the end of the paper,EMI on-ground calibration is summarized and prospected,and some deficiencies that need improvement are put forward.