Abstract
Abstract To assess the amount of ice volume stored in glaciers or ice caps, a method to estimate ice thickness distribution is required for glaciers where no direct observations are available. In this study, we use an existing inverse method to estimate the bedrock topography and ice thickness of the Renland Ice Cap, East Greenland, using satellite-based observations of the surface topography. The inverse approach involves a procedure in which an ice dynamical model is used to build-up an ice cap in steady state with climate forcing from a regional climate model, and the bedrock is iteratively adjusted until the modelled and observed surface topography match. We validate our model results against information from airborne radar data and satellite observed surface velocity, and we find that the inferred ice thickness and thereby the stored total volume of the ice cap is sensitive to the assumed ice softness and basal slipperiness. The best basal model parameters for the Renland Ice Cap are determined and the best estimated total ice volume of 384 km3 is found. The Renland Ice Cap is particularly interesting because of its location at a high elevation plateau and hence assumed low sensitivity to climate change.
Highlights
3% of the ice on Earth exist as ice caps and glaciers (Benn and Evans, 2010) located at high latitudes or in mountainous regions
The success of the inverse method to infer the bedrock topography depends on the accuracy of the input data as well as the physics of the ice flow model, and our study shows that while both these factors are important, the uncertainties in basal sliding parameters and ice softness can lead to particular large errors in the estimated ice volume for the Renland Ice Cap
We estimate the ice thickness and basal topography for the Renland Ice Cap by using an ice flow model, forced with climate data from a regional climate model (RCM) and combined with an iterative inverse method, where the bedrock heights are adjusted in order to minimise the deviation between the modelled and observed surface topography
Summary
3% of the ice on Earth exist as ice caps and glaciers (Benn and Evans, 2010) located at high latitudes or in mountainous regions. The study of glaciers and ice caps is a key subject in estimating the consequences of climate change. Remote-sensing data provide information of glacier extent worldwide, but knowledge of the ice thickness is required to estimate the total ice volume stored in a glacier or an ice cap as well as the potential contribution to sea-level rise. Simulations of past and future evolution of glaciers and ice caps in response to climate change depend strongly on the initial ice thickness and surface climate forcing. Knowledge of ice thickness is thereby an important parameter for the assessment of past, present and future glacier changes
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