Radiometric Calibration of China HJ-2B Thermal Infrared Channels Based on Multiple Ground Observations

This paper describes a novel on-orbit absolute radiometric calibration technique based on multiple ground observations for China HJ-2B thermal infrared sensor. Two types of natural surfaces were selected as references, i.e., the water bodies of Wuliangsuhai Lake and desert in Kubuqi. During the multiple ground observations, the 102F Fourier transform infrared spectrometer and SI-111 infrared radiometer were used to obtain the land surface emissivity and temperature. The atmospheric parameters were acquired from the ECMWF reanalysis data after temporal and spatial interpolation. With an atmospheric radiative transfer model (MODTRAN5.3), the measured radiance was calculated and the calibration coefficients were determined by combining satellite-observed digital number (DN). The results show that the proposed radiometric calibration accuracy is high in both two thermal infrared channels of HJ-2B, with top-of-atmosphere (TOA) radiance differences of 0.60% and 1.36%, and equivalent brightness temperature differences of 0.39K and 0.96K, respectively.