15 Feb 2023
 | 15 Feb 2023
Status: this preprint is open for discussion.

Glacial Meltwater in the Southeast Amundsen Sea: A timeseries from 1994–2020

Andrew Nicholas Hennig, David A. Mucciarone, Stanley S. Jacobs, Richard A. Mortlock, and Robert B. Dunbar

Abstract. Ice sheet mass loss from Antarctica is greatest in the Amundsen Sea sector, where ‘warm’ deep seawater melts and thins the bases of ice shelves hundreds of meters below the sea surface. We use nearly 1000 paired salinity and oxygen isotope analyses of seawater samples collected on seven expeditions from 1994 to 2020 to produce a time series of glacial meltwater inventory on the Southeast Amundsen Sea continental shelf. Water column salinity-ẟ18O yield freshwater endmember ẟ18O values from −30.2 ‰ to −28.4 ‰, demonstrating that regional freshwater content is dominated by deep glacial melt. The meltwater fractions display temporal variability in basal melting, with 800 m water column meltwater inventories from 7.7 m to 9.2 m. This result corroborates recent studies suggesting interannual variability in basal melt rates of West Antarctic ice shelves and is consistent with the Amundsen region’s influence on ocean salinity and density downstream in the Ross Sea.

Andrew Nicholas Hennig et al.

Status: open (until 12 Apr 2023)

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Andrew Nicholas Hennig et al.

Andrew Nicholas Hennig et al.


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Short summary
Glacial ice has distinct oxygen isotope fingerprints that can facilitate estimation the fraction of its meltwater in coastal Antarctic seas. ẟ18O and salinity data from seven cruises on the SE Amundsen Sea between 1994 and 2020 reveal a deep freshwater source with ẟ18O −29.3 ± 0.9 ‰, consistent with melting from the base of the ice shelf. Glacial meltwater content was variable over time and space, but the lowest in 1994 and highest in 2020.