The Cryosphere (Sep 2017)

Wind enhances differential air advection in surface snow at sub-meter scales

  • S. A. Drake,
  • J. S. Selker,
  • C. W. Higgins

DOI
https://doi.org/10.5194/tc-11-2075-2017
Journal volume & issue
Vol. 11
pp. 2075 – 2087

Abstract

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Atmospheric pressure gradients and pressure fluctuations drive within-snow air movement that enhances gas mobility through interstitial pore space. The magnitude of this enhancement in relation to snow microstructure properties cannot be well predicted with current methods. In a set of field experiments, we injected a dilute mixture of 1 % carbon monoxide (CO) and nitrogen gas (N2) of known volume into the topmost layer of a snowpack and, using a distributed array of thin film sensors, measured plume evolution as a function of wind forcing. We found enhanced dispersion in the streamwise direction and also along low-resistance pathways in the presence of wind. These results suggest that atmospheric constituents contained in snow can be anisotropically mixed depending on the wind environment and snow structure, having implications for surface snow reaction rates and interpretation of firn and ice cores.