image: A core taken from Greenland's snow layer shows that meltwater has penetrated and refrozen into solid ice. view more
Credit: Courtesy of Aaron Deskins
MISSOULA - A new $1.54 million grant from the National Science Foundation will fund University of Montana geoscientists as they study the deep layer of compacted snow covering most of Greenland's ice sheet.
Lead investigator Joel Harper and co-investigator Toby Meierbachtol, both from UM's Department of Geosciences, received $760,000 for the research at UM and $400,000 for chartering aircraft. A collaborator at the University of Wyoming also received $380,000 for the project.
The research will investigate the development of the snow layer covering Greenland as it melts during the summer months. Meltwater percolates into the underlying snow and refreezes to form deep layers of ice. The melting absorbs heat from the atmosphere, and the refreezing releases the heat into the ice sheet.
The icy snow builds up over years to form a layer of compacted dense snow called firn, which can reach up to 90 meters thick. The firn is a key component of the ice sheet; as its porous structure absorbs meltwater, it changes ice sheet elevation through compaction and influences heat exchanges between the ice sheet and the climate system.
Little is known about the firn layer's structure, temperature or thickness, and two contrasting theories explain how it has developed over time - one suggesting the layer still has the ability to absorb more meltwater and the other suggesting it does not. Research is critical to understanding whether future melt will percolate downward and refreeze in the empty pore space or be routed off the ice sheet, which has implications for sea level rise and heat transfer from the atmosphere to the ice sheet.
The project will quantify the structural and thermal frameworks of Greenland's firn layer by drilling boreholes through it to conduct measurements and experiments deep within the layer.
"The mixture of cold snow with scattered pockets of wet snow makes challenging drilling conditions because the cold drill tends to freeze to the wet snow," Harper said. "That's why there is so little known about this area."
The researchers have designed a new type of drill they hope will solve this problem, and they will use the data collected in the holes to guide computer modeling.
The team will visit the ice sheet six times in three years. A modified DC-3 airplane with skis and powerful engines will deliver the researchers near the top of the ice sheet, and from there they will make two long traverses with their equipment. The project will involve both graduate and undergraduate students.
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For more information on the research project, call Aaron Deskins in UM's Department of Geosciences at 406-243-5853 or email aaron.deskins@umontana.edu.