Seabed topography beneath Larsen C Ice Shelf from seismic soundings

Seismic reflection soundings of ice thickness and seabed depth were acquired on the Larsen C Ice Shelf in order to test a sub-shelf bathymetry model derived from the inversion of IceBridge gravity data. A series of lines were collected, from the Churchill Peninsula in the north to the Joerg Peninsula in the south, and also towards the ice front. Sites were selected using the bathymetry model derived from the inversion of free-air gravity data to indicate key regions where sub-shelf oceanic circulation may be affected by ice draft and sub-shelf cavity thickness. The seismic velocity profile in the upper 100 m of firn and ice was derived from shallow refraction surveys at a number of locations. Seismic velocities in the water column were derived from previous in situ measurements.



Uncertainties in ice and water cavity thickness are in general < 10 m. Compared with the seismic measurements, the root-mean-square error in the gravimetrically derived bathymetry at the seismic sites is 162 m. The seismic profiles prove the non-existence of several bathymetric features that are indicated in the gravity inversion model, significantly modifying the expected oceanic circulation beneath the ice shelf. Similar features have previously been shown to be highly significant in affecting basal melt rates predicted by ocean models. The discrepancies between the gravity inversion results and the seismic bathymetry are attributed to the assumption of uniform geology inherent in the gravity inversion process and also the sparsity of IceBridge flight lines. Results indicate that care must be taken when using bathymetry models derived by the inversion of free-air gravity anomalies. The bathymetry results presented here will be used to improve existing sub-ice shelf ocean circulation models.

Simple

Alternate title

Polar Data Centre (PDC) record GB/NERC/BAS/PDC/00797
Date (Publication)
2016-05-26
Citation identifier
http://www.antarctica.ac.uk/dms/metadata.php?id= / GB/NERC/BAS/PDC/00797
Point of contact
Organisation name Individual name Electronic mail address Role

British Antarctic Survey

pdc@bas.ac.uk

Custodian

Polar Data Centre; British Antarctic Survey, Natural Environment Research Council; Cambridge, CB3 0ET, UK.

Brisbourne, A.

pdc@bas.ac.uk

Originator
Maintenance and update frequency
Unknown
Keywords

  • NDGO0001

NERC OAI Harvesting

  • NERC_DDC

GCMD Parameter Valids

  • EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography

BAS Free-text keywords

  • bathymetry

  • larsen

  • seismic
Use limitation

This data is released under the UK Open Government Licence - Version 2.0



http://www.nationalarchives.gov.uk/doc/open-government-licence/version/2/

Access constraints
Other restrictions
Other constraints

This data is released under the UK Open Government Licence - Version 2.0



http://www.nationalarchives.gov.uk/doc/open-government-licence/version/2/

Language
English
Topic category
  • Geoscientific information
  • Oceans
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Begin date
2012-11-01
End date
2013-01-31
Reference system identifier
OGP / urn:ogc:def:crs:EPSG::4326
Distribution format
    Distributor contact
    Organisation name Individual name Electronic mail address Role

    Polar Data Centre - British Antarctic Survey

    pdc@bas.ac.uk

    		Distributor
    OnLine resource
    Protocol Linkage Name

    http

         		https://ramadda.data.bas.ac.uk/repository/entry/show/?entryid=afe8f567-3b2c-4af3-b289-73620dda438e

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    Dataset

    Domain consistency

    Measure identification
    INSPIRE / Conformity_001

    Conformance result

    Title

    INSPIRE Data Specification on unknown theme Guidelines
    Date
    Explanation

    See the referenced specification
    Pass
    No
    Statement

    No special comments

    Metadata

    File identifier
    GB_NERC_BAS_PDC_00797 XML
    Metadata language
    English
    Hierarchy level
    Dataset
    Date stamp
    2016-05-26
    Metadata standard name

    NERC profile of ISO19115:2003
    Metadata standard version

    1.0
    Metadata author
    Organisation name Individual name Electronic mail address Role

    British Antarctic Survey

    pdc@bas.ac.uk

    		Point of contact
    Dataset URI

    http://www.antarctica.ac.uk/dms/metadata.php?id=GB/NERC/BAS/PDC/00797

     
     

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