Ice Thickness Changes From Radar Observations Over the Southern George VI Ice Shelf
Abstract
The George VI Ice Shelf (GVIIS) is located on the western coast of the Antarctica Peninsula between Palmer Land and Alexander Island. Palmer land contains the vast majority of the Antarctic Peninsula's ice and its western flank is drained by glaciers along the English Coast that flow into the GVIIS. Due to the presence of the Circumpolar Deep Water (CDW), which flows beneath the ice shelf, the water temperatures near the ice shelf base exceed 1ºC, giving rise to rapid basal melting.
Observations of ice mass balance are crucial to our understanding of present and future sea level change. Reported changes in ice mass balance are commonly derived from satellite altimetry observations. From 2009-2019 Operation IceBridge (OIB) flew airborne geophysical surveys to bridge the gap between ICESat and ICESat-2 satellites, including ice thickness and ice surface data. During the IceBridge campaigns, three repeat survey lines were flown over GVIIS in 2011 and 2016. One of the survey lines is in front of ERS glacier (ERS profile) and the other two are ~80 km N and S. Gravity measurements from these flights were recently used to identify a constricting ridge on the ERS profile, where the water column narrows to less than 150 m between the two deeper basins of ~1000 m. This constriction likely forms the boundary between the two distinct circulations patterns proposed for the northern and southern sections of the ice shelf by Potter and Paren (1984). We interpret OIB radar between 2011 and 2016 and present changes in ice thickness of up to 250 m. Most differences are observed near the grounding line for ERS and S profile. The ice is thickening between 2011 and 2016 (up ~120 m for ERS profile and up to ~25 m to S profile) and we would expect a positive mass balance for these areas, but recent data shows that the ice mass balance is negative between 2003 and 2019 (Smith et al. 2020). Spatial and temporal resolution, as well as the proximity of our observations from the groundling line, might be influencing these differences and further investigation is under way. High basal melt rates are also observed at these spots. No significant changes on the ice thickness is observed for the N profile, meaning that the ice changes were less than the radar error, which is ~10 m. We use these data to assess the influence of the constricting ridge changes in the ice shelf mass balance- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMC028.0013C
- Keywords:
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- 0726 Ice sheets;
- CRYOSPHERE;
- 0750 Sea ice;
- CRYOSPHERE;
- 0758 Remote sensing;
- CRYOSPHERE;
- 0762 Mass balance;
- CRYOSPHERE