Abstract
The first Korean meteorological satellite, Communication, Ocean, and Meteorological Satellite (COMS) which has been operated on the geostationary orbit has to be exposed to eclipse twice a year at before and after vernal equinox and autumnal equinox. At about midnight during the eclipse season, it could be occurs the radiometric quality contamination such as solar intrusion, stray light on the image data measured by Meteorological Imager (MI). The time of the biggest impact is about April 10th in vernal season and September 2nd in autumnal season. On the image at about the same time, stripes appear at regular intervals. Especially Water Vapor (WV) channel data are conspicuous. We regard the reason of such phenomena occurrence as difference of intercept for calibration equation caused by Space Look intervals. The Space Look is the process of viewing the absolute calibration target of infrared channel on the low temperature. It is supported by comparison of getting space look values between Full Disk (FD) mode and local area observation mode of the earth. There are no stripes on the FD mode image data which gets space look data every scan lines. On the Extended Northern Hemisphere (ENH) image data which gets space look data with 36.6 seconds intervals regularly, on the other hand, many of stripes appear with regular intervals.
In this paper, we will present about occurrence and influence of the radiometric event such as stripes during eclipse season and we will also discuss about method to remove or diminish them on the image of COMS MI.
Keywords: COMS, MI, Radiometric calibration, Eclipse season, Stray light
Radiation Issue during the Eclipse Season of the COMS MI
The first Korean meteorological satellite, Communication, Ocean, and Meteorological Satellite (COMS) which has been operated on the geostationary orbit has to be exposed to eclipse twice a year at before and after vernal equinox and autumnal equinox. At about midnight during the eclipse season, it could be occurs the radiometric quality contamination such as solar intrusion, stray light on the image data measured by Meteorological Imager (MI). The time of the biggest impact is about April 10th in vernal season and September 2nd in autumnal season. On the image at about the same time, stripes appear at regular intervals. Especially Water Vapor (WV) channel data are conspicuous. We regard the reason of such phenomena occurrence as difference of intercept for calibration equation caused by Space Look intervals. The Space Look is the process of viewing the absolute calibration target of infrared channel on the low temperature. It is supported by comparison of getting space look values between Full Disk (FD) mode and local area observation mode of the earth. There are no stripes on the FD mode image data which gets space look data every scan lines. On the Extended Northern Hemisphere (ENH) image data which gets space look data with 36.6 seconds intervals regularly, on the other hand, many of stripes appear with regular intervals.
In this paper, we will present about occurrence and influence of the radiometric event such as stripes during eclipse season and we will also discuss about method to remove or diminish them on the image of COMS MI.
Keywords: COMS, MI, Radiometric calibration, Eclipse season, Stray light