Evaluating the calibration of MTSAT-1R infrared channels using collocated Terra MODIS measurements

The calibration of four MTSAT-1R infrared channels was evaluated by comparing MTSAT measurements with Terra/MODIS inferred MTSAT-equivalent brightness temperatures during August 2005 and August 2006. Theoretical relationships converting MODIS brightness temperatures to MTSAT-equivalent values were obtained and used for the comparison. Results indicate that MTSAT two split window channels are well calibrated, and no serious systematic errors or biases are found; and the MTSAT water-vapour channel shows a good linear relationship but with a warm bias up to 2K. The significant cold bias of MTSAT 3.7m channel about -6.7K in August 2005 is found to be much removed in August 2006, after correction of the electrical crosstalk between MTSAT-1R SWIR channel and WV channel starting from March 2006. Since then, calibration performances of MTSAT-1R split window channels and shortwave IR channel seem to be comparable with MODIS calibration, while the water-vapour channel shows more uncertainties up to 2K of bias.