C039-08
The simulated influence of snow on sea ice in a coupled climate model
Friday, 11 December 2020: 05:58
Virtual
Marika M Holland, National Center for Atmospheric Research, Boulder, CO, United States, David Clemens-Sewall, Dartmouth College, Thayer School of Engineering, Hanover, NH, United States, Bonnie Light, University of Washington, Seattle, WA, United States, Donald K Perovich, USA CRREL, Hanover, NH, United States, Christopher Mark Polashenski, US Army Cold Regions, Hanover, NH, United States, Madison Smith, Applied Physics Laboratory University of Washington, Seattle, WA, United States and Melinda Webster, University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK, United States
Abstract:
Snow is the most reflective natural material on Earth and is also a very effective insulator. Because of these properties, snow on sea ice has competing influences on sea ice mass budgets that differ by season. During the ice growth season, the insulating effect of snow dominates and sea ice growth is reduced with thicker or more extensive snow cover. In contrast, during the melt season, the presence of snow leads to a higher surface albedo, less absorption of solar radiation in the snow/ice surface, and a reduction in ice melt. Additionally, in some locations, snow-ice formation, in which ice mass is increased due to the surface flooding and freezing of the snow cover, becomes significant in the mass budget.
Here we use coupled climate model experiments to assess the net influence of variations in snowfall on sea ice. We find that both Arctic and Antarctic sea ice are thicker and more extensive with increased snowfall, although this response is nonlinear. While the ice state changes are similar in the two hemispheres, the ice mass budget changes that lead to this response are fundamentally different. In the Arctic, increased snow leads to less basal ice growth and less ice melt. In contrast, in response to increased snow, the Antarctic sea ice exhibits increased growth due to snow-ice formation. This is balanced by increased melt as the ice pack remains largely seasonal and almost all of the ice at the end of the growth season melts away during summer. The atmospheric response to the changing sea ice and how the ice state response differs in a warming climate are discussed.
