Abstract
COMS (Communication, Ocean, and Meteorological Satellite) has been operating since April 2011. Meteorological Imager (MI) which is the meteorological instrument of COMS has 1 visible and 4 infra-red channels. National Meteorological Satellite Center (NMSC)/KMA has developed vicarious calibration system of visible channel using cloud-free ocean, desert (Australian Simpson), water cloud (WC), deep convective cloud (DCC) and moon targets.
The results from Aug. 2011 to Feb. 2013 showed that the ratio of the bias is -12.21% for ocean target, +2.13% for desert target, -8.46% for WC target, and -10.90% for DCC target when the whole data in the scatterplot are considered for 19 months. The slope and the intercept of the regression line of the scatter plot from all targets are 0.872082 and 0.018789, corresponding ratio of the bias is -12.79%. The time series of the slope of the regression show -2.13 %/year, and this means there is no signal of sensor degradation regardless of targets.
As one of visible-calibration methods, NMSC has observed moon twice a month and used this data for long-term monitoring COMS visible channel performance since Feb. 2011. The observed moon data has been processed by Moon Processing system in IMPS (Image Processing Subsystem) of NMSC. In this Moon Processing system, the total irradiance of observed moon data is compared with ROLO model value, which is moon irradiance output model in USGS (United States Geological Survey). The results showed the ratio of bias is -5.1%, and slope variation is -0.98 %/year from Feb. 2011 to Dec. 2012. This also means there is no signal of sensor degradation.
Vicarious Calibration of COMS Visible Channel using Several Targets
COMS (Communication, Ocean, and Meteorological Satellite) has been operating since April 2011. Meteorological Imager (MI) which is the meteorological instrument of COMS has 1 visible and 4 infra-red channels. National Meteorological Satellite Center (NMSC)/KMA has developed vicarious calibration system of visible channel using cloud-free ocean, desert (Australian Simpson), water cloud (WC), deep convective cloud (DCC) and moon targets.
The results from Aug. 2011 to Feb. 2013 showed that the ratio of the bias is -12.21% for ocean target, +2.13% for desert target, -8.46% for WC target, and -10.90% for DCC target when the whole data in the scatterplot are considered for 19 months. The slope and the intercept of the regression line of the scatter plot from all targets are 0.872082 and 0.018789, corresponding ratio of the bias is -12.79%. The time series of the slope of the regression show -2.13 %/year, and this means there is no signal of sensor degradation regardless of targets.
As one of visible-calibration methods, NMSC has observed moon twice a month and used this data for long-term monitoring COMS visible channel performance since Feb. 2011. The observed moon data has been processed by Moon Processing system in IMPS (Image Processing Subsystem) of NMSC. In this Moon Processing system, the total irradiance of observed moon data is compared with ROLO model value, which is moon irradiance output model in USGS (United States Geological Survey). The results showed the ratio of bias is -5.1%, and slope variation is -0.98 %/year from Feb. 2011 to Dec. 2012. This also means there is no signal of sensor degradation.