Comparison of the in-orbit calibrations between the microwave sounders on NOAA and FY-3 satellites

This paper presents the comparison of the in-orbit calibrations between the microwave sounders on the National Oceanic and Atmospheric Administration (NOAA) 15, 16, 17, 18 and 19 and FengYun 3A (FY-3A) and FY-3B satellites using the ray-matching method over the South Pole and North Pole study area in 2011. The results show that the in-orbit calibrations of NOAA Advanced Microwave Sounding Unit A (AMSU-A/NOAA) channels are identical with averaging errors less than 0.45K, except the channel 8, in which the averaging error is up to -1.53K. The in-orbit calibrations of FY-3 Microwave Temperature Sounder (MWTS/FY-3) are basically consistent with that of AMSU-A/NOAA-19 channels, and small influence of solar illumination on MWTS/FY-3B channel 4 was observed. Large in-orbit calibration discrepancies were found between FY-3 Microwave Humidity Sounder (MWHS/FY-3) channels and AMSU-B/NOAA-16 channels, especially in MWHS/FY-3A channel 5. Strong impacts of solar illumination on MWHS/FY-3 channels 3, 4 and 5 were observed.