Correction of cirrus effects in Sentinel-2 type of imagery

Abstract

Optical satellite images are often contaminated with cirrus clouds. Thin cirrus can be detected with a channel at 1.38 µm, and an established cirrus removal method exists for visible/near-infrared (VNIR) channels in atmospheric window regions which was demonstrated with MODIS (Moderate Resolution Imaging Spectrometer) data. This contribution addresses open issues of cirrus correction for Sentinel-2 type of instruments, i.e., future spaceborne sensors such as Sentinel-2 or similar instruments. These issues are (i) an extension of the existing technique to account for cirrus during the water vapour retrieval (channel at 0.94 µm) and surface reflectance calculation to avoid reflectance artefacts at 0.94 µm, (ii) a discussion of options concerning cirrus removal in the short-wave infrared (SWIR, channels at 1.6 and 2.2 µm) region, and (iii) an analysis of channel parallax (view angle) requirements to achieve a high quality cirrus removal.