Modelling the fate of surface melt on the Larsen C Ice Shelf

Abstract

Abstract. Surface melt lakes lower the albedo of ice shelves leading to additional surface melting. This can substantially alter the surface energy balance and internal temperature and density profiles of the ice shelf. Evidence suggests that melt lakes also played a pivotal role in the sudden collapse of the Larsen B Ice Shelf in 2002.Here a recently developed, high physical fidelity model accounting for the development cycle of melt lakes is applied to the Larsen C Ice Shelf, Antarctica's most northern ice shelf and one where melt lakes have been observed. We simulate current 5 conditions on the ice shelf using weather station and reanalysis data, and investigate the impacts of potential future increases in precipitation and air temperature on melt lake formation, where concurrent increases lead to an increase in lake depth.Finally, we assess the viability of future crevasse propagation through the ice shelf due to surface meltwater accumulation.

Recent understanding of Antarctic supraglacial lakes using satellite remote sensing

“…The disappearance of hundreds of lakes in Cabinet Inlet on Larsen C over 10 days in 2003 and three weeks in 2007 is also suggestive of hydrofracture drainage (Luckman et al, 2014), as observed on Larsen B (Scambos et al, 2003(Scambos et al, , 2009. The possibility of meltwater-driven hydrofracture on Larsen C has been highlighted by 1D ice shelf model simulations of future lake distributions (Buzzard et al, 2018b). In particular, larger lakes that migrate towards the front of the Larsen C Ice Shelf under warmer atmospheric conditions may deepen sufficiently to remain unfrozen between melt seasons, thereby pre-disposing them for hydrofracture (Buzzard et al, 2018b).…”

“…The possibility of meltwater-driven hydrofracture on Larsen C has been highlighted by 1D ice shelf model simulations of future lake distributions (Buzzard et al, 2018b). In particular, larger lakes that migrate towards the front of the Larsen C Ice Shelf under warmer atmospheric conditions may deepen sufficiently to remain unfrozen between melt seasons, thereby pre-disposing them for hydrofracture (Buzzard et al, 2018b). The depleted firn air thickness of Larsen C (0.3m in western inlets) also increases the likelihood of extensive SGL ponding and future instability, driven by sustained föhn-enhanced melting (Alley et al, 2018;Holland et al, 2011).…”

“…Regional-and continental-scale ice-sheet models do not currently incorporate processes of ice shelf flexure and lake filling/draining, which may fracture ice shelves sufficiently to cause partial or complete disintegration. This limits how well SGL-ice shelf interactions can be modelled, including how lakes may promote future ice shelf instability (Banwell et al, 2013;Buzzard et al, 2018b;Robel and Banwell, 2019). Table 4 compares the features of existing SGL models and highlights that some processes are better represented in some models than others.…”

A Mathematical Model of Melt Lake Development on an Ice Shelf

“…This depth was chosen as during initial testing this was the minimum size of domain where temperature and density changes were not found to reach the bottom of the model domain. The model resolution of 5 cm grid spacing was chosen as it was found that results for resolutions of 5 cm and below were identical and therefore 5 cm was chosen as the resolution for the model in order to minimize the time taken for the model to run (Buzzard, ). The vertical domain is allowed to change to account for surface melting and snowfall.…”

“…The code was initially tested using prescribed forcing and the model was found to conserve mass with an accuracy of 99.7% and conserve energy during the solution of the heat equation with an accuracy greater than 99.9% (Buzzard, ).…”