Variability in Antarctic iceberg melt rates and connections to changes in near-terminus glacier elevation and extent
Abstract
The warming atmosphere and oceans have driven a global increase in glacier and ice sheet melt, impacting the amount of freshwater being added to the oceans. The magnitude of atmospheric and ocean warming have varied in space and time, leading to variations in the flux of icebergs to the oceans and the rate at which these icebergs are transformed to freshwater. Variations in iceberg freshwater fluxes may exert an important control on local to regional ocean stratification and circulation, yet the influx of freshwater into the Southern Ocean due to melting icebergs has not yet been quantified on a broad spatial scale. Further motivation for the examination of iceberg melt estimates comes from their potential use as a proxy to infer variations in ocean conditions near inaccessible glacier termini. Here we map patterns in iceberg melt around Antarctica through the differencing of high-resolution digital elevation models (DEMs) derived from WorldView stereo imagery. This approach has been previously applied to icebergs calved from the Greenland Ice Sheet in order to quantify both iceberg freshwater fluxes and melt rates. We use repeat stereo image-derived DEMs to estimate submarine melting of icebergs from 2011 to 2018 at 14 study sites located around Antarctica, including the Antarctic Peninsula. Initial results conform to what is expected on a regional scale, with higher melt rates for icebergs located in regions where water masses are relatively warm and lower melt rates for icebergs located in regions where colder water masses are found on the continental shelf, including in the embayments of the former Larsen A and B ice shelves. In order to assess whether variations in iceberg melting can be used to infer spatio-temporal variations in ocean forcing at glacier grounding lines and/or beneath ice shelves, we compare patterns in both near-terminus elevation and terminus position from nearby glaciers with our iceberg melt dataset.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C21B1322D
- Keywords:
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- 0720 Glaciers;
- CRYOSPHEREDE: 0720 Glaciers;
- CRYOSPHEREDE: 0728 Ice shelves;
- CRYOSPHEREDE: 0728 Ice shelves;
- CRYOSPHEREDE: 0732 Icebergs;
- CRYOSPHEREDE: 0732 Icebergs;
- CRYOSPHEREDE: 0758 Remote sensing;
- CRYOSPHEREDE: 0758 Remote sensing;
- CRYOSPHEREDE: 0774 Dynamics;
- CRYOSPHEREDE: 0774 Dynamics;
- CRYOSPHEREDE: 0776 Glaciology;
- CRYOSPHEREDE: 0776 Glaciology;
- CRYOSPHEREDE: 0794 Instruments and techniques;
- CRYOSPHEREDE: 0794 Instruments and techniques;
- CRYOSPHERE