A model of blowing snow and its predictions for sensible and latent heat flux perturbation in blowing snow events

Jingbing Xiao, Peter A. Taylor and Stephen J. Déry


During blowing snow episodes, which occur frequently in Arctic and Antarctic environments, snow particle sublimation can be a significant boundary-layer sink of sensible heat and a source of latent heat. In this process, the latent heat needed to maintain the sublimation of blowing snow particles can be obtained from three sources: sensible heat diffusing down from above into the blowing snow layer, cooling of the air, plus the blowing snow particles, and solar radiation absorbed by the particles (usually a relatively small term). Time-dependent and fetch-dependent models of blowing snow (PIEKTUK-T and -F), which incorporate transfers through a particle size spectrum and the negative feedback of relative humidity increases and temperature decreases on sublimation rate, have been developed to understand the thermodynamic effects of sublimating blowing snow particles on the atmospheric boundary layer. There are some similarities with models of evaporation spray droplets over breaking waves. The models predict that the sensible and latent heat fluxes have opposite signs under typical conditions, as we expected. With an increase of wind speed, the absolute value of the sensible and latent heat fluxes increase. For example, when the wind speed increases from 10 to 25 m/s under typical conditions, the sensible heat flux minimum changes from -12 to -162 W m-2, and the latent heat flux maximum increase from 47 to 213 W m-2. The heat flux perturbations associated with sublimation of blowing snow decrease with fetch or time since the process is self-limiting due to reduced sublimation with increased relative humidity.