Research On Key Technologies Of Polarization Cross Calibration On The Same Platform

The impact of aerosols on global climate and the environment through interaction with solar radiation has attracted more and more attention.However,in Earth’s atmosphere,the distribution of aerosols in the atmosphere and their microphysical properties are still unknown.Therefore,the development of high-precision aerosol space exploration missions is extremely urgent.The cooperative observation of the same platform dual polarization instrument is one of the future development directions of atmospheric aerosol high precision space detection.It is of great significance to retrieve the comprehensive characteristic parameters of atmospheric aerosol by using two or more polarization remote sensors or different polarization detection methods to obtain the high precision comprehensive characteristic parameters of aerosol.This paper carries out the key technology research of polarization cross calibration on the same platform,including the establishment of the cross calibration model of the dual polarization instruments POSP and SIPC,the development and verification of cross calibration in-flight experiments,and the evaluation of the uncertainty of cross calibration transfer.POSP and SIPC are hosted on the same platform to form the same platform dual polarization instruments,where POSP is equipped with an onboard calibration system that can provide high precision measurements of the atmospheric or earth surface radiation polarization,while SIPC is not equipped with an onboard calibration system.In order to ensure and improve the accuracy of the polarization measurement of SIPC,this paper carries out cross calibration studies of absolute radiometric calibration coefficients and relative gain coefficients of different optical paths from POSP to SIPC hosted on the same platform,realizing the high-precision calibration transfer of POSP polarization detection data to SIPC,and the cross calibration transfer results are obtained according to the in-flight experiment,which verified the feasibility of the cross calibration method of dual polarization instruments on the same platform.Specifically,firstly,according to the imaging characteristics and working principle of the dual polarization instruments,the system radiometric measurement models of POSP and SIPC are established,and the calibration methods of the dual polarization instruments POSP and SIPC are studied.In addition,the polarization detection experiment of the dual polarization instruments are designed to verify the correctness of the system radiometric measurement models and the accuracy of the calibration models in the case of known polarization light source and external field natural target.Next,the cooperative working modes of the same platform dual polarization instruments are introduced,and the cross calibration model of the dual polarization instruments are deduced.In addition,the in-flight verification platform of the dual polarization instruments is built,while the multi-load comprehensive detection in-flight experiment is carried out.Meanwhile,the cross calibration transfer results of the ocean surface and land surface types with different uniformity are calculated according to the cross calibration coefficients and cross calibration models of the same platform dual polarization instruments POSP and SIPC in the in-flight experiment.Finally,the uncertainty transfer theory in parametric measurement is introduced,and the uncertainty sources of POSP and SIPC in the cross calibration transfer process and the influence of each uncertainty factor on the cross calibration transfer results are analyzed.At the same time,the uncertainty of the cross calibration transfer of SIPC radiance and polarization degree are evaluated.The results show that the radiance and polarization trends of the ocean and land surface obtained by the dual polarization instrument POSP and SIPC hosted on the same platform are in good agreement,and for the results of polarization detection on the uniform land targets,the radiance deviation of SIPC relative to the POSP is 2.5372%and the polarization deviation is 0.0125.In addition,the uncertainty of cross calibration transfer of radiance and polarization is 3.325%and 0.209%,respectively.The research on the polarization cross calibration method on the same platform is carried out to realize the value transfer of the high precision calibration parameters between POSP and SIPC,so as to improve the comprehensive application performance of the PCF sensor in orbit detection,which is the basis the realization of high-precision aerosol detection and inversion,providing technical support for cross calibration of spaceborne "Polarization CrossFire" sensors.At the same time,it also provides a valuable reference for cross calibration of other cooperative observation remote sensors in the world.