[PS3-B.67]
Evolution of firn layers over time
1,2 1
ZR Courville , MR Albert*
1 2
University of New Hampshire, United States, Cold Regions Research and Engineering
3
Laboratory, United States, Dartmouth College, United States
For the past seven years, the physical properties of snow and firn layers in snow pits dug at
Summit Station, Greenland, have been examined. Summit Station is a year-long research
station located at the summit of the Greenland Ice Sheet, an area that experiences melt
extremely rarely. In this region, snow layers persist year after year, are buried by
subsequent storms, and undergo firn metamorphism, primarily driven by diurnal temperature
gradients in the top two meters. Repeat pits at exact locations have been dug and analyzed
for stratigraphy, grain size, air permeability, thermal conductivity and gas diffusivity. The
spatial variability of the snow from small to large scale has been examined, as well as the
temporal variability of the near surface snow. The evolution of these physical properties have
been tracked over time. In general, we see an increase in permeability, gas diffusivity, and
thermal conductivity as a snow layer ages. These changes in physical properties are linked to
changes in the firn microstructure due to temperature gradient metamorphism. This work
has helped to further understand firn air models of past atmospheric conditions, as well as
help to support current photochemistry experiments.
Keywords: firn, microstructure, physical properties