On-orbit Radiometric Calibration for Thermal Infrared Band of FY3D/MERSI-II Satellite Remote Sensor Based on Qinghai Lake radiation calibration test-site

In August 2018, an on-orbit absolute radiometric calibration test for the thermal infrared channel of FY3D/MERSI-II satellite remote sensor was carried out at the Qinghai lake radiation correction test-site. The spectral radiance data of Qinghai Lake was obtained by means of fixed-point measurement. The sounding data were input to radioactive transfer model that computers the at-sensor radiance and brightness temperature of the satellite, and the calibration coefficients for thermal infrared channel 24 (10.26~11.26 μm) and channel 25 (11.50~12.50 μm) of FY3D/MERSI-II was calculated. Using AQUA/MODIS and NPP/VIIRS satellite remote sensors which have high calibration accuracy to evaluate the accuracy of the on-orbit radiometric calibration method, The average deviation of the channel brightness temperature is less than 0.5 K in the range of 10.26~11.26 μm and 1.0 K in the range of 11.50~12.50 μm, indicating that the on-orbit radiometric calibration method has better calibration accuracy, and the calibration results are reasonable and reliable. Comparing the on-orbit calibration results using the Qinghai Lake with the on-board calibration results, in the range of 10.26 ~ 11.26 μm and 11.50 ~ 12.50 μm, the average deviation of the channel brightness temperature is less than 0.5 K and 1.25 K, respectively. It shows that FY3D/MERSI-II runs stably on orbit. This test verified the FY3D/MERSI-II on-board calibration results, and provided a guarantee for the quantitative application of FY3D / MERSI-II remote sensing data.