Geometric Accuracy Improvement of Geostationary Environment Monitoring Spectrometer by Pixel Offset Adjustment

초록

In this study, we propose a method of improving the geometric accuracy of Geostationary Environment Monitoring Spectrometer (GEMS). We propose to apply a shift offset, whose value is derived using Advanced Meteorological Imager (AMI) data as a reference. After performing collocation processes to align spatiotemporal and spectral characteristics of GEMS and AMI images, GEMS images were shifted within a ±5-pixel range in both vertical and horizontal directions. Correlation coefficients were then calculated through matching shifted GEMS images with collocated AMI images. The shift value at which the correlation coefficient reached its maximum was defined as the optimal offset. This value was then applied to GEMS images to compare geometric accuracy before and after adjustment. Using GEMS data acquired from January 2023 to July 2025, experiment results showed that geometric errors occurred mainly in the north-south direction, with a magnitude of about one pixel. After applying optimal offset, geometric errors were reduced to within one pixel in most cases. These results demonstrate that the proposed shift offset correction method can effectively improve the geometric accuracy of GEMS image. © ACRS 2025.All rights reserved.

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