Fengyun Program and Solar Observation Activities

Fengyun 3 series (FY-3) is the second generation polar orbiting meteorological satellite in China. There are 5 satellites have been launched since the first satellite FY-3A in 2008. The solar irradiance is one of important parameters to measure by FY-3 series. The instrument to measure the solar irradiance is called Solar Irradiance Monitor (SIM). The SIM was deployed on the orbit since FY-3A (morning orbit AM) in 2008 and FY-3B (afternoon orbit PM) in 2010. SIM was upgraded to SIM-II mounted on FY-3C (AM orbit) in 2013. The sensitivity, absolute accuracy and stability of the instrument has been improved with the more accurate control on the solar disk tracking system and instrument environment temperature maintaining system. The SIM-II together with the Solar Spectral Irradiation Monitor (SSIM) have been deployed on the orbit mounted on FY-3E (early-morning orbit EM) in 2021. This presentation overviews the FY program. The specification and performance of SIM, SIM-II and SSIM have been illustrated. The measured Total Solar Irradiance (TSI) product has been compared with the similar measurements on SOHO/VIRGO, SORCE, TSIS-1, etc. The future plan for the solar measurements in FY-3 series has been presented in the last part.