Articles | Volume 12, issue 1
The Cryosphere, 12, 189–204, 2018
The Cryosphere, 12, 189–204, 2018

Research article 19 Jan 2018

Research article | 19 Jan 2018

Modelling debris transport within glaciers by advection in a full-Stokes ice flow model

Anna Wirbel1, Alexander H. Jarosch2, and Lindsey Nicholson1 Anna Wirbel et al.
  • 1Institute of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, Austria
  • 2Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland

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. Because 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 knowledge of englacial transport pathways and deformation. 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 2-D and 3-D 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 (i) a debris-aware surface mass balance scheme and (ii) a supraglacial debris transport scheme will enable the co-evolution of debris cover and glacier geometry to be modelled.

Short summary
As debris cover affects the meltwater production and behaviour of glaciers it is important to understand how, and over what timescales, it forms. Here we develop an advanced 3-D numerical model that describes transport of sediment through a glacier to the point where it emerges at the surface. The numerical performance of the model is satisfactory and it reproduces debris structures observed within real-world glaciers, thereby offering a useful tool for future studies of debris-covered glaciers.