Articles | Volume 10, issue 6
Research article
24 Nov 2016
Research article |  | 24 Nov 2016

Effects of local advection on the spatial sensible heat flux variation on a mountain glacier

Tobias Sauter and Stephan Peter Galos

Abstract. Distributed mass balance models, which translate micrometeorological conditions into local melt rates, have proven deficient to reflect the energy flux variability on mountain glaciers. This deficiency is predominantly related to shortcomings in the representation of local processes in the forcing data. We found by means of idealized large-eddy simulations that heat advection, associated with local wind systems, causes small-scale sensible heat flux variations by up to 100 Wm−2 during clear sky conditions. Here we show that process understanding at a few observation sites is insufficient to infer the wind and temperature distributions across the glacier. The glacier-wide hourly averaged sensible heat fluxes are both over- and underestimated by up to 16 Wm−2 when using extrapolated temperature and wind fields. The sign and magnitude of the differences depend on the site selection, which is used for extrapolation as well as on the large-scale flow direction. Our results demonstrate how the shortcomings in the local sensible heat flux estimates are related to topographic effects and the insufficient characterization of the temperature advection process.

Short summary
The paper deals with the micrometeorological conditions on mountain glaciers. We use idealized large-eddy simulations to study the heat transport associated with the local wind systems and its impact on the energy exchange between atmosphere and glaciers. Our results demonstrate how the sensible heat flux variablility on glaciers is related to topographic effects and that the energy surplus is strong enough to significantly increase the local glacier melting rates.