The effect of aeolian deposition on the surface roughness of melting snow, Byers Peninsula, Antarctica
2010
Fassnacht, S.R. | Toro Velasco, M. | Meiman, P.J. | Whitt, Z.C.
The surface of the snowpack is the bottom boundary layer for air movement, and its roughness influences aerodynamics. The presence of aeolian deposits on a snowpack decreases its albedo and is shown to decrease the roughness of the surface. During snowmelt in the Lake Limnopolar basin on Byers Peninsula of Livingston Island of the South Shetland Islands, Antarctica, wind moved coarse soil grains (1-4 mm particles) from a bare, dry and snow-free area to an adjacent snowpack. This addition of large soil particles rapidly changed the snowpack surface characteristics. Within several days, the sun-cups, initially present on the melting snow surface, had been smoothed out in areas where soil was deposited on the snow surface. The differences in the snowpack surface were assessed using digital imagery of a roughness board inserted into the snow, both parallel and perpendicular to the dominant wind direction. The random roughness was twice as variable for the clean snow compared to the snow with soil; it was 27% more and 26% less perpendicular versus parallel to the wind for the clean snow and snow with soil, respectively. Variogram analysis showed that the clean snow had up to four different scales of roughness over the 55 x 55 cm area of analysis, with fractal dimensions varying from 1·33 to 1·83. The snow with soil did not vary substantially from 0·1 to 55 cm with fractal dimensions of 1·65 in parallel and perpendicular to the wind.
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