The role of advection in the energy balance of late‐lying snowfields: Niwot Ridge, Front Range, Colorado

Measured profiles of temperature, humidity, and wind above alpine tundra are used as upwind boundary conditions in a numerical model for simulating turbulent transfer over late‐laying snow. Resulting simulations indicate that (1) sensible heat flux comprises the major source of turbulent melt energy, although its relative importance vis‐a‐vis latent heat flux depends upon ambient weather conditions, and (2) advected heat contributes greatly to the energy balance of late‐lying alpine snow. Near the leading edge of a snowfield, advection may contribute more than 30 MJ m⁻² d⁻¹ of melt energy on a very windy day and more than 12 MJ m⁻² d⁻¹ on a relatively windless day. The totals decrease to circa 5 MJ m⁻² d⁻¹ and 2 MJ m⁻² d⁻¹ at a distance of 1000 m from the leading edge. These findings suggest that the sensible heat flux may exceed net radiation as the major source of energy available for melting late‐lying snow in windy alpine environments.