Abstract
A partial aperture onboard calibration method can solve the onboard calibration problems of some large aperture remote sensors, which is of great significance for the development trend of increasingly large apertures in optical remote sensors. In this paper, the solar diffuser reflectance degradation monitor (SDRDM) in the onboard calibration assembly (CA) of the FengYun-4 (FY-4) advanced geostationary radiance imager (AGRI) was used as the reference radiometer. It was designed for measuring the partial aperture factor (PAF) for the AGRI onboard calibration. First, the linear response count variation relationship between the two was established under the same radiance source input. Then, according to the known bidirectional reflection distribution function (BRDF) of the solar diffuser (SD) in the CA, the relative reflectance ratio coefficient between the AGRI observation direction and the SDRDM observation direction was calculated. On this basis, the response count value of the AGRI and the SDRDM was used to realize the high-precision measurement of the PAF of the AGRI B1~B3 bands by simulating the AGRI onboard calibration measurement under the illumination of a solar simulator in the laboratory. According to the determination process of the relevant parameters of the PAF, the measurement uncertainty of the PAF was analyzed; this uncertainty was greater than 2.04% and provided an important reference for the evaluation of the onboard absolute radiometric calibration uncertainty after launch.
Highlights
Publisher’s Note: MDPI stays neutralThe level of remote sensing data quantification is an important aspect of the advanced technology of remote sensing
Based on the relative relationship between the characteristics of the advanced geostationary radiance imager (AGRI) calibration assembly (CA) and the actual work of the AGRI, this paper proposes a method to measure the partial aperture factor (PAF) of the AGRI calibration optical path by using the solar diffuser reflectance degradation monitor (SDRDM) in the CA as the reference radiometer
The onboard calibration method of the partial aperture all-optical path based on the solar diffuser (SD) was characterized by decreasing the complexity of the calibration system to reduce the volume of the CA, which provided a solution for the onboard absolute radiometric calibration of large aperture remote sensors
Summary
Publisher’s Note: MDPI stays neutralThe level of remote sensing data quantification is an important aspect of the advanced technology of remote sensing. The quality of remote sensing data directly affects the correctness of the research directions of the natural sciences and the accuracy of the results. The types, functions and working methods of space remote sensors differ with the rapid development of science and technology and the diverse needs of in-depth research on the earth. The corresponding radiometric calibration methods and technical research have always explored the radiometric calibration schemes of various remote sensors and have continuously improved the radiometric calibration accuracy. When the remote sensor had a large aperture or the when available space of the remote sensor was insufficient, onboard calibration methods based on the solar diffuser (SD), such as the partial aperture all-optical path and partial optical with regard to jurisdictional claims in published maps and institutional affiliations
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