Systematic Error Correction of GMS-4 IR Data


About 7 to 10 anomalous peaks are found in the histogram analysis of a Geostationary Meteorological Satellite (GMS-4) infrared (IR) image. These extra peaks, called systematic errors, need to be corrected before the GMS-4 image data are applied in the study of cloud climatology, rainfall estimation and hydrologic cycles. Because an Advanced Very High Resolution Radiometer (AVHRR) IR image is free of such systematic errors, it serves as a reference for GMS-4 IR data correction in this study. It is noted that when comparing the pixels without systematic errors in GMS-4 IR image data with the corresponding National Oceanic and Atmospheric Administration (NOAA) AVHRR Channel 4 data, a good linear relationship emerges. In view of the effects caused by different observation times in order to obtain a stable relationship between the GMS-4 IR brightness temperature (Tb) and AVHRR IR Tb, it is necessary that scattering criteria be set when selecting the samples used to determine the regression equation. The results show that if the histogram¡¦s anomalous peak samples located outside the 95% confidence interval are corrected by applying the regression equation, the histogram¡¦s anomalous peaks almost disappear. 

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