Variability of ice shelf-influenced fast ice and the sub-ice platelet layer
Abstract
High Salinity Shelf Water produced in coastal polynyas drives basal melting of Antarctic ice shelves and the formation of relatively cold and fresh Ice Shelf Water at depth. The outflow of supercooled Ice Shelf Water from ice shelf cavities manifests as accelerated sea ice formation, increased sea ice thicknesses, and the formation of a porous sub-ice platelet layer. We assessed variability in the distribution and thickness of ice shelf-influenced land-fast sea ice and the sub-ice platelet layer in McMurdo Sound in late-spring of 2011, 2013, 2016 and 2017 with ground-based electromagnetic induction (EM), EM modelling techniques and drill-hole surveys. Thicker sub-ice platelet layers were observed in 2011 and 2017. Fast ice formation throughout the preceding winters of the same years was influenced by a higher occurrence of strong southerly wind events and more frequent polynya-activity in the south-western Ross Sea. In contrast, low wind conditions in 2016 led to largely undisturbed sea ice growth and anomalously extensive fast ice coverage. A thinner sub-ice platelet layer was observed in 2016. We demonstrate that variability in strong southerly wind events, resultant polynya-activity and High Salinity Shelf Water production during winter accelerates circulation and increases melting in the nearby McMurdo Ice Shelf cavity, and consequently the outflow of supercooled Ice Shelf Water and sub-ice platelet layer formation in McMurdo Sound.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C53C1376B
- Keywords:
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- 0728 Ice shelves;
- CRYOSPHERE;
- 0774 Dynamics;
- CRYOSPHERE;
- 0776 Glaciology;
- CRYOSPHERE;
- 0798 Modeling;
- CRYOSPHERE