Topographic Controls on Supraglacial Meltwater Drainage Systems on Antarctic Ice Shelves.
Abstract
Surface meltwater ponding on floating ice shelves has been tied to ice shelf break-up through meltwater-induced fracturing, i.e hydrofracturing. Drainage systems on the surface of Antarctic ice shelves move water long distances and observations suggest further distances of transport if melt rates increase in coming decades, as is predicted. Enlarged surface drainage systems could deliver water to areas with ice stresses that render them vulnerable to hydrofracture, which recent work has shown are often located downstream of drainage systems. Therefore, part of understanding the future of Antarctica's ice shelves, and by extension, improving predictions of Antarctic sea level contributions, is understanding the first-order controls on the growth of drainage systems. Previous work indicates that topography controls drainage system structure. We compare catchments and basins derived from the Reference Elevation Model of Antarctica (REMA) (where catchments are the watershed of each closed depression and basins are the areas surrounding each depression where water would pond before overtopping into the next catchment) to Landsat-derived drainage systems on several ice shelves, including Amery Ice Shelf, East Antarctica. This allows us to examine the proportion of the accommodation capacity of ice shelves that is regularly filled by melt. We also characterize ice-shelf surface hydrology using metrics relevant to longitudinal drainage-system growth, including the along-ice-flow length of each catchment and the ratio of catchment area to basin volume. We discuss (1) how these metrics provide a simple, first-order indicator of how drainage systems may respond to increases in surface melting, (2) their spatial distribution in relation to areas identified by previous work as vulnerable to hydrofracture, and (3) possible environmental explanations for their distribution. With further development, this approach may provide a simple method of including ice-shelf hydrology in ice-sheet models.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMC022.0023S
- Keywords:
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- 0728 Ice shelves;
- CRYOSPHERE;
- 0774 Dynamics;
- CRYOSPHERE;
- 0776 Glaciology;
- CRYOSPHERE