Internal accumulation on Storglaciären, Sweden, in a multi-layer snow model coupled to a distributed energy- and mass balance model

Abstract

To investigate the internal accumulation on Storglaciären, Sweden, we couple a multilayer snow model to a distributed energy- and mass-balance model. The snow model describes the temperature, density and water-content evolution of the snow/ice pack and includes the processes of percolation and refreezing of water. The model is run for the period 9 May-2 September 1999 and validated against weather station and mass-balance observations on the glacier. The model performs reasonably well, with an average summer mass balance for the location of stake observations of −1.56 m w.e. compared to −1.59 m w.e. observed. However, the amount of melt is overestimated in the higher parts of the accumulation area and underestimated in the lower parts of the ablation area. The modelled mass balance is most sensitive to the albedo parameterization, the chosen momentum and scalar roughness lengths and all parameters related to snowfall. The modelled internal accumulation is +0.25 m w.e., which amounts to about 20% of the winter accumulation and results in a positive net balance for 1999 of +0.23 m w.e. The modelled internal accumulation is most sensitive to the initial subsurface temperature profile and the irreducible water content.