Greenland Bare Ice Albedo Modeling

A large portion of melt from the Greenland Ice Sheet (GrIS) comes from regions with dark bare ice, because dark ice absorbs more incoming sunlight than regions with bright snow. Earth System Models, which simulate changes in the Earth’s climate and the impacts of these changes, prescribe the reflectivity of these dark ice regions as a constant. This work shows that treating bare ice as though it has a constant reflectivity is not a good approximation, because the dark ice regions change as the winter snowpack melts and impurities accumulate on the ice surface. This work improves how the reflectivity of bare ice is calculated by incorporating a new physical model into the Energy Exascale Earth System Model and uses satellite measurements to inform the new model. The improvements made here show that previous methods overestimate the reflectivity of bare ice, meaning they underestimate how much light is absorbed and how much melt comes from the bare ice regions on the GrIS. It is important to have more accurate methods for determining the reflectivity of bare ice regions, as this will ultimately lead to improved estimates of sea-level rise.

This work was published in JGR-Atmospheres in 2024, you can read more here.