In the Chinese weather satellite program, the first two research and experiment satellites FengYun-3A (FY-3A) and FengYun-3B (FY-3B) were successfully launched into orbit on May 27, 2008 and November 5, 2010, respectively, and the remaining five operational satellites will be launched once every two years. FY-3A/B satellites cover the mid-morning and afternoon orbits. The following eleven instruments are on board both FY-3A and FY-3B: (1) Visible and InfRared Radiometer (VIRR); (2) MEdium ReSolution Imager (MERSI); (3) InfRared Atmospheric Sounder (IRAS); (4) MicroWave Temperature Sounder (MWTS); (5) MicroWave Humidity Sounder (MWHS); (6) MicroWave Radiation Imager (MWRI); (7) Solar Backscatter Ultraviolet Sounder (SBUS); (8)Total Ozone Mapping Unit (TOU); (9) Earth Radiation Measurer (ERM); (10) Solar Irradiation Monitor (SIM); and (11) Space Environment Monitor (SEM). Read More