Modelling debris transport within glaciers by advection in a full-Stokes ice flow model
Abstract. Glaciers with extensive surface debris cover respond differently to climate forcing than those without supraglacial debris. In order to include debris-covered glaciers in projections of glaciogenic runoff and sea-level rise, and to understand the paleoclimate proxy recorded by such glaciers it is necessary to understand the manner and timescales over which a supraglacial debris cover develops. As debris is delivered to the glacier by processes that are heterogeneous in space and time, and these debris inclusions are altered during englacial transport through the glacier system, correctly determining where, when, and how much, debris is delivered to the glacier surface requires that the englacial transport pathways and deformation can be known. To achieve this, we present a model of englacial debris transport in which we couple an advection scheme to a full-Stokes ice flow model. The model performs well in numerical benchmark tests, and we present both 2D and 3D steady-state glacier test cases that, for a set of prescribed debris inputs, reproduce the englacial features, deformation thereof, and patterns of surface emergence predicted by theory and observations of structural glaciology. In a future step, coupling this model to a (i) debris-aware surface mass-balance scheme and (ii) supraglacial debris transport scheme will enable the co-evolution of debris-cover and glacier geometry to be modelled.