Circulation and melting beneath George VI Ice Shelf, Antarctica
Oceanographic data are presented from the eastern Bellingshausen Sea, representing the first near-contemporaneous sampling of conditions near both the northern and southern ice fronts of George VI Ice Shelf. Circumpolar Deep Water (CDW) with a temperature in excess of 1 degrees C floods the entire c...
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American Geophysical Union
2008
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ftnerc:oai:nora.nerc.ac.uk:11529 2023-05-15T13:45:10+02:00 Circulation and melting beneath George VI Ice Shelf, Antarctica Jenkins, Adrian Jacobs, Stan 2008-04 text http://nora.nerc.ac.uk/id/eprint/11529/ https://nora.nerc.ac.uk/id/eprint/11529/1/2007JC004449.pdf https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007JC004449 en eng American Geophysical Union https://nora.nerc.ac.uk/id/eprint/11529/1/2007JC004449.pdf Jenkins, Adrian orcid:0000-0002-9117-0616 Jacobs, Stan. 2008 Circulation and melting beneath George VI Ice Shelf, Antarctica. Journal of Geophysical Research, 113 (C4), C04013. https://doi.org/10.1029/2007JC004449 <https://doi.org/10.1029/2007JC004449> Marine Sciences Glaciology Publication - Article PeerReviewed 2008 ftnerc https://doi.org/10.1029/2007JC004449 2023-02-04T19:27:25Z Oceanographic data are presented from the eastern Bellingshausen Sea, representing the first near-contemporaneous sampling of conditions near both the northern and southern ice fronts of George VI Ice Shelf. Circumpolar Deep Water (CDW) with a temperature in excess of 1 degrees C floods the entire continental shelf and forms the main inflow to the cavity beneath the ice shelf. We use measurements of salinity, potential temperature, stable isotope ratios and dissolved oxygen, helium, and neon to show that the outflows contain meltwater in concentrations that rise to a maximum of around 3%. Assuming that the currents are in geostrophic balance, we calculate relative velocities along the ice front sections, then estimate the absolute velocity by inversion of the tracer conservation equations. We obtain an overall mean melt rate of 3-5 m a(-1) and a net south-to-north throughflow beneath the ice shelf of 0.17-0.27 Sv. The mean melt rate exceeds that required for equilibrium, consistent with recent observations of ice shelf thinning and retreat. Melting beneath the ice shelf drives upwelling of about 0.1 Sv in total of CDW into the surface mixed layer at the two ice fronts. The effective vertical heat flux per unit area of ice shelf cover is 8 W m(-2), more than 4 times that estimated for vertical diffusion through the main pycnocline of the neighboring open water region. The south-to-north throughflow carries a particularly strong signature of upwelled CDW, including low dissolved oxygen and high nutrient concentrations, north into Marguerite Bay. Article in Journal/Newspaper Antarc* Antarctica Antarctica Journal Bellingshausen Sea George VI Ice Shelf Ice Shelf Natural Environment Research Council: NERC Open Research Archive Bellingshausen Sea George VI Ice Shelf ENVELOPE(-67.840,-67.840,-71.692,-71.692) Marguerite ENVELOPE(141.378,141.378,-66.787,-66.787) Marguerite Bay ENVELOPE(-68.000,-68.000,-68.500,-68.500) Journal of Geophysical Research 113 C4 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
topic |
Marine Sciences Glaciology |
spellingShingle |
Marine Sciences Glaciology Jenkins, Adrian Jacobs, Stan Circulation and melting beneath George VI Ice Shelf, Antarctica |
topic_facet |
Marine Sciences Glaciology |
description |
Oceanographic data are presented from the eastern Bellingshausen Sea, representing the first near-contemporaneous sampling of conditions near both the northern and southern ice fronts of George VI Ice Shelf. Circumpolar Deep Water (CDW) with a temperature in excess of 1 degrees C floods the entire continental shelf and forms the main inflow to the cavity beneath the ice shelf. We use measurements of salinity, potential temperature, stable isotope ratios and dissolved oxygen, helium, and neon to show that the outflows contain meltwater in concentrations that rise to a maximum of around 3%. Assuming that the currents are in geostrophic balance, we calculate relative velocities along the ice front sections, then estimate the absolute velocity by inversion of the tracer conservation equations. We obtain an overall mean melt rate of 3-5 m a(-1) and a net south-to-north throughflow beneath the ice shelf of 0.17-0.27 Sv. The mean melt rate exceeds that required for equilibrium, consistent with recent observations of ice shelf thinning and retreat. Melting beneath the ice shelf drives upwelling of about 0.1 Sv in total of CDW into the surface mixed layer at the two ice fronts. The effective vertical heat flux per unit area of ice shelf cover is 8 W m(-2), more than 4 times that estimated for vertical diffusion through the main pycnocline of the neighboring open water region. The south-to-north throughflow carries a particularly strong signature of upwelled CDW, including low dissolved oxygen and high nutrient concentrations, north into Marguerite Bay. |
format |
Article in Journal/Newspaper |
author |
Jenkins, Adrian Jacobs, Stan |
author_facet |
Jenkins, Adrian Jacobs, Stan |
author_sort |
Jenkins, Adrian |
title |
Circulation and melting beneath George VI Ice Shelf, Antarctica |
title_short |
Circulation and melting beneath George VI Ice Shelf, Antarctica |
title_full |
Circulation and melting beneath George VI Ice Shelf, Antarctica |
title_fullStr |
Circulation and melting beneath George VI Ice Shelf, Antarctica |
title_full_unstemmed |
Circulation and melting beneath George VI Ice Shelf, Antarctica |
title_sort |
circulation and melting beneath george vi ice shelf, antarctica |
publisher |
American Geophysical Union |
publishDate |
2008 |
url |
http://nora.nerc.ac.uk/id/eprint/11529/ https://nora.nerc.ac.uk/id/eprint/11529/1/2007JC004449.pdf https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007JC004449 |
long_lat |
ENVELOPE(-67.840,-67.840,-71.692,-71.692) ENVELOPE(141.378,141.378,-66.787,-66.787) ENVELOPE(-68.000,-68.000,-68.500,-68.500) |
geographic |
Bellingshausen Sea George VI Ice Shelf Marguerite Marguerite Bay |
geographic_facet |
Bellingshausen Sea George VI Ice Shelf Marguerite Marguerite Bay |
genre |
Antarc* Antarctica Antarctica Journal Bellingshausen Sea George VI Ice Shelf Ice Shelf |
genre_facet |
Antarc* Antarctica Antarctica Journal Bellingshausen Sea George VI Ice Shelf Ice Shelf |
op_relation |
https://nora.nerc.ac.uk/id/eprint/11529/1/2007JC004449.pdf Jenkins, Adrian orcid:0000-0002-9117-0616 Jacobs, Stan. 2008 Circulation and melting beneath George VI Ice Shelf, Antarctica. Journal of Geophysical Research, 113 (C4), C04013. https://doi.org/10.1029/2007JC004449 <https://doi.org/10.1029/2007JC004449> |
op_doi |
https://doi.org/10.1029/2007JC004449 |
container_title |
Journal of Geophysical Research |
container_volume |
113 |
container_issue |
C4 |
_version_ |
1766214612541243392 |