  Sublimation of drifting snow, which is significant for the balances of mass
and energy of the polar ice sheet, is a complex physical process with
intercoupling between ice crystals, wind field, temperature, and moisture. Here
a three-dimensional drifting snow sublimation model in a turbulent boundary
layer is proposed. In contrast to most previous models, it takes into account
turbulent diffusion of moisture from lower to higher elevations, allowing the
air humidity near the surface to be undersaturated and thus sublimation to
occur. From simulations with this model, we find that snow sublimation in the
saltation layer near the surface dominates overall snow sublimation, despite an
only marginal departure from humidity saturation ($<1\%$), because of a large
particle concentration.
