Evaluating GOES ABI Band-to-Band Co-registration Accuracy at Sub-Satellite Point

The GOES Advanced Baseline Imager (ABI) has 16 spectral bands with different spatial resolution. Its geolocation performance is routinely validated using selected subsets of clear sky Landsat images, or “chips”, that are often found along the coast lines of continents and large islands. There are few chips for GOES-West to assess the image navigation and registration performance at the sub-satellite point (SSP). This study evaluates the accuracy of band-to-band co-registration (BBR) for GOES-18 ABI at SSP using simultaneous nadir observations (SNO) with NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) data. For each matched SNO pairs, the VIIRS data are shifted at sub-pixel level with fast Fourier transform (FFT) function and resampled to the ABI spatial resolutions using the ABI resampling algorithm. The reconstructed VIIRS radiance are then correlated with the matched ABI data to derive the registration difference between the ABI and VIIRS images. The ABI BBR accuracy is then assessed using the VIIRS data as the reference. The preliminary results indicate that the GOES-18 ABI BBR difference in this study is generally less than 6 µrad in the east-west and north-south directions for the bands located at the same focal plane module and less than 8 µrad for the IR bands across different focal plane modules.