Early Orbit Performance Evaluation of FY-3D MERSI-II and HIRAS Using GSICS Methods

FY-3D satellite was successfully launched at 2:35UTC am on November 15, 2017, and a new member of Fengyun satellite family was added.FY-3D is the forth satellite of China's second generation polar orbiting meteorological satellite with a design life of 5 years. FY-3D is equipped with 10 sets of remote sensing instruments, among which, Hyperspectral InfRared Atmospheric Sounding instrument (HIRAS), Greenhouse Gases Absorption Spectrometer GAS, Wide-angle Aurora Imager WAI and Ionospheric PhotoMeter IPM are completely new instruments and Medium Resolution Spectral Imager MERSI-II is an significantly upgraded instrument with respect to MERSI-1. MicroWave Temperature Souder (MWTS), MicroWave Humidity Souder (MWHS), MicroWave Radimetric imager (MWRI), Global Navigation Satellite System Occultation Sounder GNOS and Space Environment Monitor SEM are inherited instruments. The application of these new instruments further improves the spectral resolution and spatial observation accuracy, comprehensively enhances the NWP model satellite data assimilation capability, and improves weather forecasting. The key performance evaluation of FY-3D MERSI-II and HIRAS including the spectral calibration, radiometric calibration and geolocation accuracy was conducted using GSICS platform at CMA GSICS research processing center (GPRC). The GSICS-consensus reference instruments IASI, CrIS, MODIS and VIIRS are used to evaluate the radiometric accuracy of MERSI-II and HIRAS. In addition to this, the accurate collocation and inter-comparison between MERSI-II and HIRAS at the same satellite platform FY-3D gave us several important information of their performance, especially the knowledge of HIRAS subpixel geolocation shift. Based on the above GSICS evaluation, mechanism behind radiometric calibration bias of MERSI-II and HIRAS also were found including the non-linearity, polarization effect and other parameters of the instruments. These parameters were updated several times based on comprehensive assessment and iterative validation during the commissioning test.