Understanding the response of fast flowing ice streams or outlet glaciers to changing climate is crucial in order to make reliable projections of sea level change over the coming decades. Motion of fast outlet glaciers occurs largely through basal motion governed by physical processes at the glacier bed, which are not yet fully understood. Various subglacial mechanisms have been suggested for fast flow but common to most of the suggested processes is the requirement of presence of liquid water, and thus temperate conditions.
We use a combination of modelling, field, and remote observations in order to study links between different heat sources, the thermal regime and basal sliding in fast flowing areas on Vestfonna ice cap. A special emphasis lies on Franklinbreen, a fast flowing outlet glacier which has been observed to accelerate recently. We use the ice flow model Elmer/Ice including a Weertman type sliding law and a Robin inverse method to infer basal friction parameters from observed surface velocities. Firn heating, i.e. latent heat release through percolation of melt water, is included in our model; its parameterisation is calibrated with the temperature record of a deep borehole. We found that strain heating is negligible, whereas friction heating is identified as one possible trigger for the onset of fast flow. Firn heating is a significant heat source in the central thick and slow flowing area of the ice cap and the essential driver behind the ongoing fast flow in all outlets.
Arctic Centre, University of Lapland, Rovaniemi, Finland; Finnish Meteorological Institut, Helsinki, Finland; Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS-Univ. Grenoble Alpes, Grenoble, France; Department of Earth Sciences, Air, Water and Landscape Science, Uppsala University, Uppsala, Sweden; Gamma Remote Sensing and Consulting AG, Gümligen, Switzerland; CSC-IT Center for Science Ltd., Espoo, Finland
Recommended Citation:
Schäfer M,, Gillet-Chaulet F,, Gladstone R,et al. Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard[J]. Cryosphere,2014-01-01,8(5)