LAUSR

From a distance of about one-and-a-half million kilometers, the Earth Polychromatic Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR) spacecraft takes roughly hourly images of the sunlit side of the Earth. Earlier studies showed that these images often feature sun glint from water surfaces and from ice crystals that are suspended inside clouds in a horizontal orientation. This letter draws a wider view of the earlier analyses of observed glints caused by clouds, focusing on how the appearance of these glints varies with wavelength and season. The statistical analysis of all EPIC images taken in 2017 reveals that the wavelength dependence of glints is mainly shaped by the Rayleigh scattering and gaseous absorption caused by the air above the cloud top. The analysis also reveals that the radiative impact of cloud glints displays seasonal variations that are consistent with seasonal changes in the prevalence of ice clouds that were observed independently by the Moderate Resolution Imaging Spectroradiometer (MODIS).