Evaluation for radiometric calibration of infrared band of FY-3A medium resolution spectral imager(MERSI) using radiometric calibration sites

This investigation compared the brightness temperatures observed by infrared band of FY-3A MERSI using on-board radiometric calibration coefficients with that simulated surface observation data. The primary surface data were collected from the simultaneous observation in Qinghai Lake site in 2008, 2009 and Dunhuang site in 2010, and buoy data in Qinghai Lake site in 2008 and 2009. Seven and eighteen groups of available data from the simultaneous observation data using optical instruments and buoy data in Qinghai Lake were used. It was found that the observed brightness temperatures by medium resolution spectral imager(MERSI) sensor were basically higher than the results derived from buoy data at nighttime, and the results were opposite at daytime. To sum up, the results from both simultaneous observation and buoy data indicate that the brightness temperatures observed by MERSI sensor are 1.721.18 K, which are systematically higher than the simulated results using surface observation data, which is mainly attributed to the variations of emissivity of on-board blackbody without calibration.