Fengyun Meteorological Satellites and Consideration on Calibration Issues

This presentation introduces the history, current status and perspective of Chinese Fengyun meteorological satellite (FY). Up to now, there are 17 FY meteorological satellites have been launched successively. Currently, there are 8 satellites simultaneously kept on the orbit, 7 in operation and 1 in commission test. 3 latest launched satellites are FY-3D, FY-4A and TFY-2H. After the completion of the commission test, FY-4A has been announced to transit into operation in May 1, 2018. The commission test for FY-3D has been completed also and will be transit into operation in the end of 2018. FY-2H has been launched on June 5, 2018 and will provide the service to the countries along the Belt and Road with the coverage of IOC region after the commission test before the end of this year.

FY series satellite program has gone through four stages. The first stage primarily conducts the research and the development (R&D) for satellite technology. The lifetime of the satellite fails to meet the requirement. FY-1A operates for 39 days and FY-1B for 158 days. Meanwhile, FY-2A operates for about 6 months and FY-2B for about 8 months. The second stage implements the transition from the R&D satellites to the operational satellites. After, since FY-1C in 1999 and FY-2C in 2004, FY satellites start to keep stable on the orbit and support continuous measurements in an operational way. The third stage deploys transition from first generation satellites to second generation satellites. In recent decade, the upgrading of the new-generation FY polar and GEO satellites has been completed from FY-3A in 2008 and FY-4A in 2016. Multiple types of advanced instruments have been mounted on the platform of FY satellites, including multiband optical imaging, atmospheric sounding, microwave sounding/imaging, hyper-spectral trace gases detecting and full-band radiation budget measuring. The new epoch for the comprehensive earth observations has been established. The latest and current stage is focusing on the accuracy and precision of the satellite measurements. The high performances of navigation and radiometric calibration are indispensable to support various quantitative data applications, such as quantitative remote sensing, satellite data assimilation and so forth. With the open data policy, stable and accurate measurements, FY satellites are becoming an important component of the international space-based global observing system.

The radiometric calibration (hereafter calibration) is the most essential activity for quantitative remote sensing applications. The sensor’s performance in radiance measurement relies on three necessary procedures, i.e., pre-launch calibration procedure, real time (RT) calibration procedure (or on-orbit calibration), and re-calibration procedure (or offline calibration). The recent progress on the calibration and validation for the instruments has been introduced. The onboard calibration system of the sensor has been emphasized.