Sensitivity of grounding line flux change to ice shelf kinematics and dynamics
Abstract
Dynamic or climate-induced thinning can decrease the "buttressing" effect of ice shelves, resulting in increased ice flux across the grounding line and potentially leading to marine ice sheet retreat. However, the precise physical mechanisms linking thinning to reduced ice shelf buttressing and increased grounding line flux are still unclear. This is particularly true for complex patterns of ice shelf thinning, e.g., those resulting from realistic sub-ice shelf melt rates applied to realistic ice shelf geometries. Here, we aim to address questions of which locations on an ice shelf are the most sensitive to thinning-induced reduction in buttressing and why. Using two state-of-the-art ice flow models - the 3D Stokes Finite Element Land Ice eXperiments - Stokes model (FELIX-S; Zhang et al., 2017) and the Model For Prediction Across Scales - Albany Land Ice (MALI ; Hoffman et al., 2018), which uses the first-order Stokes approximation - we investigate the impacts of basal melt perturbations applied to different locations of an ice shelf on the ice flux across grounding line. We examine results from both 2D flowline and 3D plan-view simulations. By inspecting modeled stress and strain-rate fields, we find that grounding line flux and the propagation of stress perturbations from floating to grounded regions are sensitive to the spatial patterns of 1) ice flow, 2) ice shelf geometry, and 3) sub-ice-shelf melt rate. These factors combine and impact buttressing in subtle and non-intuitive ways. We find that the speedup of an ice sheet/shelf system due to sub-ice-shelf melting follows not only from changes in lateral stress gradients, but also from changes in the driving stress and longitudinal stress gradients. This initial idealized work will ultimately be expanded to more realistic domains and forcing scenarios in order to better understand patterns of ice sheet vulnerability to loss of ice shelf buttressing as a function of spatially and temporally variable patterns of sub-ice shelf melting.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C31C1525Z
- Keywords:
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- 0726 Ice sheets;
- CRYOSPHEREDE: 0728 Ice shelves;
- CRYOSPHEREDE: 0730 Ice streams;
- CRYOSPHEREDE: 0798 Modeling;
- CRYOSPHERE