Kinematic response of ice-rise divides to changes in ocean and atmosphere forcing
<p>The majority of Antarctic ice shelves are bounded by grounded ice rises. These ice rises exhibit local flow fields that partially oppose the flow of the surrounding ice shelves. Formation of ice rises is accompanied by a characteristic upward-arching internal stratigraphy (“Raymond arches”)...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2019-10-01
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Series: | The Cryosphere |
Online Access: | https://www.the-cryosphere.net/13/2673/2019/tc-13-2673-2019.pdf |
Summary: | <p>The majority of Antarctic ice shelves are bounded by grounded ice rises.
These ice rises exhibit local flow fields that partially oppose the
flow of the surrounding ice shelves. Formation of ice rises is
accompanied by a characteristic upward-arching internal stratigraphy
(“Raymond arches”), whose geometry can be analysed to infer information
about past ice-sheet changes in areas where other archives such as rock
outcrops are missing. Here we present an improved modelling framework to
study ice-rise evolution using a satellite-velocity calibrated,
isothermal, and isotropic 3-D full-Stokes model including grounding-line
dynamics at the required mesh resolution (<span class="inline-formula"><</span>500 m). This overcomes
limitations of previous studies where ice-rise modelling has been
restricted to 2-D and excluded the coupling between the ice shelf and ice
rise. We apply the model to the Ekström Ice Shelf, Antarctica, containing
two ice rises. Our simulations investigate the effect of surface mass
balance and ocean perturbations onto ice-rise divide position and
interpret possible resulting unique Raymond arch geometries. Our results
show that changes in the surface mass balance result in immediate and
sustained divide migration (<span class="inline-formula">>2.0</span> m yr<span class="inline-formula"><sup>−1</sup></span>) of up to 3.5 km. In contrast,
instantaneous ice-shelf disintegration causes a short-lived and delayed
(by 60–100 years) response of smaller magnitude (<span class="inline-formula"><0.75</span> m yr<span class="inline-formula"><sup>−1</sup></span>). The model
tracks migration of a triple junction and synchronous ice-divide
migration in both ice rises with similar magnitude but differing rates.
The model is suitable for glacial/interglacial simulations on the
catchment scale, providing the next step forward to unravel the
ice-dynamic history stored in ice rises all around Antarctica.</p> |
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ISSN: | 1994-0416 1994-0424 |