Parameterizing Scalar Transfer over Snow and Ice: A Review

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Abstract
Evaluating the profiles of wind speed, temperature, and humidity in the atmospheric surface layer or modeling the turbulent surface fluxes of sensible and latent heat over horizontally homogeneous surfaces of snow or ice requires five pieces of information. These are the roughness lengths for wind speed (z0), temperature (zT), and humidity (zQ) and the stratification corrections for the wind speed and scalar profiles ψm and ψh, respectively. Because over snow and ice the atmospheric surface layer is often stably stratified, the discussion here focuses first on which of the many suggested ψm and ψh functions to use over snow and ice. On the basis of four profile metrics—the critical Richardson number, the Deacon numbers for wind speed and temperature, and the turbulent Prandtl number—the manuscript recommends the Holtslag and de Bruin ψm and ψh functions because these have the best properties in very stable stratification. Next, a reanalysis of five previously published datasets confirms the valid... Abstract Evaluating the profiles of wind speed, temperature, and humidity in the atmospheric surface layer or modeling the turbulent surface fluxes of sensible and latent heat over horizontally homogeneous surfaces of snow or ice requires five pieces of information. These are the roughness lengths for wind speed (z0), temperature (zT), and humidity (zQ) and the stratification corrections for the wind speed and scalar profiles ψm and ψh, respectively. Because over snow and ice the atmospheric surface layer is often stably stratified, the discussion here focuses first on which of the many suggested ψm and ψh functions to use over snow and ice. On the basis of four profile metrics—the critical Richardson number, the Deacon numbers for wind speed and temperature, and the turbulent Prandtl number—the manuscript recommends the Holtslag and de Bruin ψm and ψh functions because these have the best properties in very stable stratification. Next, a reanalysis of five previously published datasets confirms the valid...