Modelling the influence of a supraglacial debris cover on the mass balance and dynamics of mountain glaciers using a 3D higher order ice flow model

We have modelled the influence of a supraglacial debris cover on the behavior of an idealized reference mountain glacier. A calibrated 3D coupled ice flow-mass balance-supraglacial debris cover model is used to assess the impact of the melt-altering effect of various supraglacial debris deposit rates on the overall steady state characteristics of the glacier. Additional experiments are also carried out to simulate the behavior of the debris-covered glacier in a warming future climate. The main results show that, when compared to its clean-ice version, the debris-covered version of the glacier exhibits longer but thinner ablation zones, accompanied by lower ice flow velocities, lower runoff production, as well as a dampening of the mass balance-elevation profile over the debris-covered ice. Experiments for warming climatic conditions primarily point out towards a significant delay of glacier retreat, as the dominant process for ice mass loss encompasses thinning out of the ablation zone rather than retreat. The above-mentioned effects are modelled to be increasingly pronounced with an increasing thickness and extent of the superimposed supraglacial debris cover.