Albedo (surface reflectivity) is an important component of global climate models. Dark surfaces such as open water or melt ponds in the Arctic absorb more energy than light surfaces such as snow or ice. The increased heat absorption raises the temperature of the water, melting more ice, which in turn raises the temperature further.
In spring, a foot or two of snow covers ice on the Arctic Ocean. As temperatures and moisture increase, snow melts and collects on top of the ice. Next, cracks form in the ice, eventually forming melt conduits. Water drains and the ice is lifted up, leaving smaller areas of melt ponds that deepen and widen over time, eventually melting through.
Observations suggest that melt pond number and sizes on sea ice are governed mainly by the ice topography at the beginning of the melt season, and that smooth first-year ice behaves much differently from multi-year ice. Eric Skyllingstad and Karen Shell are applying a detailed sea ice model over a limited surface area and examining how ponds form given different sea ice properties.
Results from these experiments will be compared to field data from the SHEBA experiment and recent observations off the coast of Barrow Alaska.
The objective of their study is to better understand and model the thermodynamic processes that control the evolution of sea ice.
• Develop a thermodynamic sea ice model with directly resolved melt ponds, using observational data to initialize and test the model;
• Conduct model experiments to examine how the initial ice surface topography and snow cover affect the formation of melt ponds and overall melting rate;
• Determine if the effects of pond size and distribution can be adequately parameterized in climate models using existing pond volume methods or if ice thickness distributions are required; and
• Quantify the effect of current and altered climate model parameterizations on the modeled Arctic climate and climate change.
Shell notes, “By using observations to initialize and test the melt-pond model, we gain confidence in the validity of that model and then we can use the model in different situations to get a bigger picture of the ice dynamics. ”
Article courtesy of the College of EArth, Ocean, and Atmospheric Sciences 2010 Research Highlights