Simulation of the specific surface area of snow using a one-dimensional physical snowpack model: implementation and evaluation for subarctic snow in Alaska 1CNRS/Université Joseph Fourier – Grenoble 1, Laboratoire de Glaciologie et Géophysique de l'Environnement, St. Martin d'Hères, France
2Geophysical Institute and Department of Chemistry and Biochemistry, University of Alaska, Fairbanks, Alaska
3US Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, Alaska
Received: 13 Jul 2009 – Published in The Cryosphere Discuss.: 08 Sep 2009 Abstract. The specific surface area (SSA) of the snow constitutes a powerful parameter
to quantify the exchange of matter and energy between the snow and the
atmosphere. However, currently no snow physics model can simulate the SSA.
Therefore, two different types of empirical parameterizations of the
specific surface area (SSA) of snow are implemented into the existing
one-dimensional snow physics model CROCUS. The parameterizations are either
based on diagnostic equations relating the SSA to parameters like snow type
and density or on prognostic equations that describe the change of SSA
depending on snow age, snowpack temperature, and the temperature gradient
within the snowpack. Simulations with the upgraded CROCUS model were
performed for a subarctic snowpack, for which an extensive data set
including SSA measurements is available at Fairbanks, Alaska for the winter
season 2003/2004. While a reasonable agreement between simulated and
observed SSA values is obtained using both parameterizations, the model
tends to overestimate the SSA. This overestimation is more pronounced using
the diagnostic equations compared to the results of the prognostic
equations. Parts of the SSA deviations using both parameterizations can be
attributed to differences between simulated and observed snow heights,
densities, and temperatures. Therefore, further sensitivity studies
regarding the thermal budget of the snowpack were performed. They revealed
that reducing the thermal conductivity of the snow or increasing the
turbulent fluxes at the snow surfaces leads to a slight improvement of the
simulated thermal budget of the snowpack compared to the observations.
However, their impact on further simulated parameters like snow height and
SSA remains small. Including additional physical processes in the snow model
may have the potential to advance the simulations of the thermal budget of
the snowpack and, thus, the SSA simulations.
Revised: 16 Dec 2009 – Accepted: 04 Jan 2010 – Published: 21 Jan 2010
Citation: Jacobi, H.-W., Domine, F., Simpson, W. R., Douglas, T. A., and Sturm, M.: Simulation of the specific surface area of snow using a one-dimensional physical snowpack model: implementation and evaluation for subarctic snow in Alaska, The Cryosphere, 4, 35-51, doi:10.5194/tc-4-35-2010, 2010.