The Importance of Snow Distribution on Sea Ice

Abstract:

Snow’s insulating and reflective properties substantially influence Arctic sea ice growth and decay. A particularly important, but under-appreciated, aspect of snow on sea ice is its fine-scale spatial distribution. Snow redistribution into dunes and drifts controls the effective thermal conductivity of a snowpack and dictates the locations of melt pond formation, exerting considerable control over ice mass balance. The effective thermal conductivity of snow distributions created on sea ice, for example, is often considerably greater than a uniform snowpack of equivalent mean thickness. During the N-ICE 2015 campaign north of Svalbard, we studied snow distributions across multiple ice types and the impacts these have on thermal fluxes and ice mass balance. We used terrestrial LiDAR to observe the snow surface topography over km² areas, conducted many thousands of manual snow depth measurements, and collected hundreds of observations of the snow physical properties in snow pits. We find that the wind driven redistribution of snow can alter the net effect of a constant snow cover volume on ice mass balance as strongly as inter-annual variability in the amount and timing of snowfall. Further comparison with snow depth distributions from field campaigns in other parts of the Arctic highlights regional and inter-annual differences in snow distribution. We quantify the impact of this variability on ice mass balance and demonstrate the need for considering snow distributions and redistribution processes in sea ice models.