On shear-driven ventilation of snow

Andrew Clifton, Costantino Manes, Jean Daniel Rüedi, Michele Guala, Michael Lehning

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46 Scopus citations


A series of experiments have been made in a wind tunnel to investigate the ventilation of snow by shear. We argue that the zero-plane displacement can be used as a convenient indicator of ventilation, and that this can be obtained from measurements of mean velocity profiles in conditions of zero pressure gradient. Measurements made over a natural snow surface show a zero-plane displacement depth of less than 5 mm, but practical considerations preclude extensive use of snow for these measurements. Instead, the influence of permeability is investigated using reticulated foams in place of snow. We demonstrate that the foam and snow have similar structure and flow-relevant properties. Although the surface of the foam is flat, the roughness lengths increase by two orders of magnitude as the permeability increases from 6 × 10-9 to160 × 10-9 m2. The zero-plane displacement for the least permeable foams is effectively zero, but more than 15 mm for the most permeable foams. Our data compare well to the few studies available in the literature. By analogy to conditions over snow surfaces, we suggest that shear-driven ventilation of snow is therefore limited to the upper few millimetres of snow surfaces.

Original languageEnglish (US)
Pages (from-to)249-261
Number of pages13
JournalBoundary-Layer Meteorology
Issue number2
StatePublished - Feb 2008

Bibliographical note

Funding Information:
Acknowledgements This work was partially financed by the Swiss National Foundation. T. Exner, R. Grant, D. Ambühl, V. Smith, A. Craig and the SLF Workshop were invaluable for help preparing the wind tunnel and the techniques we applied. We thank T. Neumann and Z. Courville for measuring the foam permeability.

Copyright 2008 Elsevier B.V., All rights reserved.


  • Boundary-layer meteorology
  • High latitudes
  • Porous media
  • Snow
  • Ventilation
  • Zero-plane displacement


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