Influence of the BB temperature on the on-orbit radiometric calibration for the medium resolution spectral imager

Abstract

As one key imaging sensor carried on the fengyun-3C (FY-3C), the medium resolution spectral imager (MERSI) is capable of making continuous global observations for a broad range of scientific studies of the earth and ocean together with the atmosphere and land. In order to acquire the on-orbit radiometric data with good accuracy and stability, the errors of the calibration coefficients a0 and a1 caused by the BB temperature offset are analyzed in detail. For the BB temperature changing by 0.1 K, the calibration coefficient errors δa0 and δa1 are in a range of 0.001,0.015 and 8×10−6,9×10−6. To verify the effectiveness of the calibration coefficient, the earth reversed irradiance and temperature obtained by the calibration coefficients and earth gray value are compared with the theoretical irradiance and temperature, and the absolute variation of the earth irradiance is 0.01 Wm-2sr-1μm-1 while the relative error is about 0.16 %. Besides, the earth equivalent temperature difference is 0.10 K, whose relative error is 0.04 %. This research provides a theoretical and practical guidance for the satellite data assimilations along with the quantitative remote sensing applications.