Mark Pittard1, Ben Galton-Fenzi2,3, Jason Roberts2,3, Christopher Watson4
1Department of Geography, Durham University, Durham, United Kingdom, 2Australian Antarctic Division, Kingston, Australia, 3Antarctic Climate & Ecosystems Cooperative Research Centre, Hobart, Australia, 4School of Land and Food, University of Tasmania, Hobart, Australia
Geothermal heat flux is one of the key thermal boundary conditions for simulations of ice flow. We assess the sensitivity of the Lambert-Amery glacial system within the East Antarctic Ice Sheet to both local and regional variations in geothermal heat flux using the Parallel Ice Sheet Model. Geothermal heat flux can vary locally through elevated radiogenic heat production, with heat flow modelling within the Lambert-Amery glacial system estimating localised elevated geothermal heat flux of at least 120 mWm-2. To assess the influence of these local high heat flux regions on ice flow, we insert a geothermal heat flux anomaly into the dataset beneath five different types of ice flow. Geothermal heat flux can also vary more broadly, with different techniques of estimating geothermal heat flux producing different spatial patterns of heat flux. Using four different geothermal datasets scaled to the same median heat flux we assess the importance of the spatial variation on regional ice flow.
The simulations show that localised high heat flow regions can significantly enhance flow in slow-moving ice, with the influence extending both upstream and downstream of the anomaly. The scaled regional simulations demonstrate this further, with the ice divides being the most sensitive to regional variations in ice flow. Additionally, the position of the onset of basal sliding, in addition to the width of the region experiencing basal sliding was dependent on the underlying geothermal heat flux. Our results suggest that localized regions of elevated geothermal heat flux may play an important role in the organisation of ice sheet flow.