The instruments on-board the three-axis stabilized Geostationary (GEO) spacecrafts not only provide continuous streams of satellite data for timely weather monitoring and forecasting, the quantitative meteorological products, such as sea surface temperature, winds, and precipitation, are also important inputs to the numerical weather prediction systems and the global climate change studies. Two instruments, Imager and Sounder, are carried in the series of the Geostationary Operational Environmental Satellites (GOES) operated by National Oceanic and Atmospheric Administration (NOAA) of the United States (US) for the observations of the US and its neighboring environments over the past decades. However, GOES infrared (IR) channels experience calibration errors around the satellite midnight time, mainly due to the extra radiation contamination at the blackbody during the calibration events, causing diurnal calibration variation of the GOES IR channels. To compensate for the erroneous midnight responsivity of Imager data, NOAA implemented an empirical midnight blackbody calibration correction (MBCC) since 2003.

Recent results of the Global Space-based Inter-calibration System (GSICS) inter-calibration of the GEO data with two well-calibrated hyperspectral instruments on low earth orbit (LEO) satellites, Atmospheric Infrared Sounder (AIRS) on-board the Aqua satellite and the Infrared Atmospheric Sounding Interferometer (IASI) on-board the Metop-A satellite, show that both GOES Imager and Sounder IR channels experience diurnal calibration variation around satellite midnight time, even with the implementation of MBCC at GOES Imager IR channels. The magnitude and phase of diurnal variation vary at different IR channels and change with time. This diurnal calibration variation is also observed at the 3-axis stabilized MTSAT-2 (Multifunctional Transport Satellite) operated by Japanese Meteorological Agency (JMA), and should be also available at COMS (Communication, Ocean and Meteorological Satellite) by Korean Meteorological Agency (KMA). In this study, we use the two pairs of GSICS GEO-LEO collocation data (GOES-AIRS and GOES-IASI) to develop the time-dependent correction for the GOES IR instruments, using the IASI data as reference. As GOES with AIRS and IASI collocation data cover different time in a day, the delta-correction is used to transfer the GOES-AIRS inter-calibration correction and its uncertainty to IASI standard. More detailed results will be presented in the coming meeting.