INTER CALIBRATION OF FY-2B IR CHANNEL WITH NOAA SATELLITES

FY-2 is a spin scanning geostationary meteorological satellite. The calibration of IR channel in -orbit was to insert a blackbody into objective optical path from back end optical path. There was a big error for such calibration, but tha twasn't a total optic path calibration. For the infrared channels, the pre-launch calibration was conducted in a vacuum container used to simulate the space environment. The instrument was calibrated with reference to the black body. The radiant cooler was keeping at two tempera tures states, i.e. 95　K，100　K in the laboratory. The objective blackbody vari ed with a series of the temperatures. Then the infrared sensors were measured in variety combined temperatures conditions of the primary mirror and second mirror. The sensors output voltages with response were also measured. But, the char acteristic response of sensors was varying by time after the satellite launched. The pre-calibration was no longer useful. Thus the calibration post launch wa s very importance. There were a variety of calibration methods post-launch about the black-body calibration, the calibration of the radiometric calibrated sit es, the calibration of radiant numeric data and the inter calibration with diff erent satellites. The 27 th CGMS meeting in 1999 stressed the importance of inter -calibration.  In CMA/NSMC, the inter-calibration study is carried out and is operationorien ted. The intercalibration uses NOAA satellite data to calibrate FY-2 geostati onary satellite. The data were used for calibrating FY-2 long wave IR channel. The inter-calibration examination was processed by the GAC data of AVHRR channe l4 from NOAA 16, 17 that were high precision calibration. The intercalibrati on jobs were mainly the spectral matching between two response functions of sate llites measured sensors and the geometry matching between two images observed. T he calibration coefficient of FY-2B was ameliorated by the better calibration coefficient of NOAA satellites after matching two satellites data were calculated . The inter-calibration precision of FY-2B IR channel was highly enhanced.