RADIOMETRIC CALIBRATION ON ORBIT FOR FY-2B METEOROLOGICAL SATELLITE' S VISIBLE CHANNELS WITH THE RADIOMETRIC CALIBRATION SITE OF DUNHUANG

Pre-launch calibration of the FY-2B's visible channels has much error due to the influence of stray light. The radiometric calibration on orbit for FY-2B's visible channels might be running with the radiometric calibration site of Dunhuang's Gobi. There are must calibrated the BRDF of bi-direction characteristic of Dunhuang's site, because the zenith is close to 50°. The reflectance of the Gobi, light extinction of atmosphere and radiosonde observation were measured in synchronization for FY-2B in July 2002, while the bi-direction characteristics of the site were measured. The data processed results indicate that the calibration precision are debased 20% due to influence of stray light for FY-2B's visible channels, and the output of FY-2B's visible channels is very stabilization after long stakeout. The calibration tables calibrated by the site of four visible channels were listed.