Insights into the composition of ice clouds, based on spaceborne observations of sun glints from horizontally oriented ice crystals

Satellite images often feature sun glints caused by the specular reflection of sunlight not only from the ocean surface but also from horizontally oriented ice crystals occurring in clouds. The accompanying image shows a sample glint from ice clouds over South Sudan. Such glints can complicate the interpretation of observations but can also provide insights into the composition of ice-containing clouds. Satellite observations of sun glint can help improve our knowledge about the shape of ice crystals, which cause significant uncertainties in satellite retrievals of cloud properties and in calculations of cloud radiative forcing and cloud lifetime.

This presentation will briefly describe the operational sun glint product of the Earth Polychromatic Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR) spacecraft. Additionally, it will also discuss the impact of glints in the EPIC operational cloud product, focusing on cloud detection, cloud optical thickness, and cloud altitude. Finally, the presentation will show glint statistics based on a combination of satellite observations that provide information about the prevalence of horizontally oriented crystals in ice clouds.