Stray light performance comparison between Himawari-8 AHI and GOES-16 ABI

Both the Advanced Himawari Imager (AHI) aboard Japanese geostationary weather satellite Himawari-8 and Advanced Baseline Imager (ABI) aboard the American GOES-16 satellite are the primary imaging instruments with multispectral channels and have very similar optical design. The Himawari-8 was launched ~two years earlier than the GOES-16 ABI. Since the AHI imagery data become available, characterization, monitoring and trending the stray light performance in AHI imageries have been routinely performed. Difference data between consecutive AHI full-disk images were processed and the stray light performance was quantitatively assessed for the regions inside and outside the restricted zone around the sun that intercept with the AHI full-disk images. It has been found that the major stray light contamination occurred in the full disk imagery of the AHI VNIR and IR channels over a few weeks around February and October-November. Because of the observed AHI stray light in 3.9 um channel, the ABI design has been modified. Analysis of ABI imagery data confirms that the stray light performance of the ABI 3.9 um channel is better than AHI.