baef2e88-300f-42bc-8ccb-bfdff147a492 eng utf8 dataset dataset NERC EDS UK Polar Data Centre +44 (0)1223 221400 British Antarctic Survey, High Cross, Madingley Road Cambridge Cambridgeshire CB3 0ET United Kingdom polardatacentre@bas.ac.uk https://www.bas.ac.uk/team/business-teams/information-services/uk-polar-data-centre/ information pointOfContact 2025-12-02 ISO 19115 Geographic Information - Metadata ISO 19115:2003(E) European Petroleum Survey Group (EPSG) Geodetic Parameter Registry 2008-11-12 publication European Petroleum Survey Group EPSGadministrator@iogp.org https://www.epsg-registry.org/ EPSG Geodetic Parameter Dataset The EPSG Geodetic Parameter Dataset is a structured dataset of Coordinate Reference Systems and Coordinate Transformations, accessible through this online registry. information publisher urn:ogc:def:crs:EPSG::3031 6.18.3 Updated gravity-derived bathymetry for the Thwaites, Crosson and Dotson ice shelves (2009-2022) 2025-12-02 creation 2025-12-02 revision 2025-12-02 publication 2025-12-02 released 1.0 https://doi.org/10.5285/baef2e88-300f-42bc-8ccb-bfdff147a492 doi GB/NERC/BAS/PDC/02123 https://data.bas.ac.uk/ NE/S006419/1 award Please cite this item as: Jordan, T., Heywood, K., Wahlin, A., Hall, R., Muto, A., Dutrieux, P., Hogan, K., Girton, J., Alley, K., & Pettit, E. (2025). Updated gravity-derived bathymetry for the Thwaites, Crosson and Dotson ice shelves (2009-2022) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/baef2e88-300f-42bc-8ccb-bfdff147a492 This dataset is an estimate of sub ice shelf bathymetry beneath the Thwaites, Crosson and Dotson ice shelves. The output bathymetry is derived from a compilation of gravity data collected up to the end of the 2018/19 field season. The input gravity dataset includes airborne data from Operation Ice Bridge (OIB) and the NERC/NSF International Thwaites Glacier Collaboration (ITGC), and marine gravity from the R/V Nathaniel B. Palmer cruise NBP19-02. The recovered bathymetry was constrained by swath bathymetry in the open ocean, onshore airborne radio-echo depth sounding data and sub-shelf bathymetric observations from autonomous marine systems sent beneath the Dotson and Crosson Ice Shelves and seismic observations from the Crosson Ice Shelf surface. This bathymetric dataset supersedes the dataset of Jordan et al. 2020 (https://doi.org/10.5285/7803de8b-8a74-466b-888e-e8c737bf21ce ), as the new direct observations of sub-shelf bathymetry revealed the previously estimated depth of the basin beneath the Crosson and Dotson region to be ~400m too shallow. This inaccuracy is attributed to isostatic compensation of the deep basin, the mantle gravity effect of which was not considered in the original model. Included in the data release is the input free air gravity data, constraining bathymetry/sub-ice topography, isostatic gravity model, output gravity derived bathymetry including consideration of isostatic compensation which improves the fit to the new observed sub-shelf data and a final revised bathymetry dataset which incorporates the bathymetry from the gravity model with all bathymetric constraints. This work was funded by the Thwaites-Amundsen Regional Survey and Network Integrating Atmosphere-Ice-Ocean Processes (TARSAN) project, a component of the International Thwaites Glacier Collaboration (ITGC), from National Science Foundation (NSF: Grant 1929991) and Natural Environment Research Council (NERC: Grant NE/S006419/1) No credit. completed Jordan, Tom British Antarctic Survey Researcher author Heywood, Karen University of East Anglia Researcher author Wahlin, Anna University of Gothenburg Researcher author Hall, Robert University of East Anglia Researcher author Muto, Atsuhiro Dept. of Earth and Environmental Science, Temple University Researcher author Dutrieux, Pierre British Antarctic Survey Researcher author Hogan, Kelly British Antarctic Survey Researcher author Girton, James University of Washington School of Oceanography Researcher author Alley, Karen University of Manitoba Researcher author Pettit, Erin Oregon State University Press Researcher author NERC EDS UK Polar Data Centre +44 (0)1223 221400 British Antarctic Survey, High Cross, Madingley Road Cambridge Cambridgeshire CB3 0ET United Kingdom PDCServiceDesk@bas.ac.uk https://www.bas.ac.uk/team/business-teams/information-services/uk-polar-data-centre/ information pointOfContact asNeeded completed EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography > Bathymetry EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography > Seafloor Topography EARTH SCIENCE > Cryosphere > Glaciers/Ice Sheets EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography EARTH SCIENCE > Solid Earth > Geodetics/Gravity theme Global Change Master Directory (GCMD) Science Keywords 2026-01-27 publication 23 Global Change Data Center, Science and Exploration Directorate, Goddard Space Flight Center (GSFC) National Aeronautics and Space Administration (NASA) Greenbelt MD United States of America https://earthdata.nasa.gov/about/gcmd/global-change-master-directory-gcmd-keywords Global Change Master Directory (GCMD) Keywords The information provided on this page seeks to define how the GCMD Keywords are structured, used and accessed. It also provides information on how users can participate in the further development of the keywords. information publisher Bathymetry Gravity Ice shelf West Antarctic theme Thwaites Glacier Antarctica Amundsen Sea Antarctica Crosson Ice Shelf Antarctica Dotson Ice Shelf Antarctica place Oceanographic geographical features Elevation Geology theme GEMET - INSPIRE themes, version 1.0 2021-01-06 revision otherRestrictions public access limited according to Article 13(1)(e) of the INSPIRE Directive license Open Government Licence v3.0 otherRestrictions Data supplied under Open Government Licence v3.0 otherRestrictions Data under embargo until the publication of the associated paper url url crossReference doi doi crossReference textTable eng utf8 elevation geoscientificInformation oceans -113.097 -105.215 -76.37 -73.452 2009-01-01 2022-03-31 It is recommended that careful attention be paid to the contents of any data, and that the author be contacted with any questions regarding appropriate use. If you find any errors or omissions, please report them to polardatacentre@bas.ac.uk. NERC EDS UK Polar Data Centre +44 (0)1223 221400 British Antarctic Survey, High Cross, Madingley Road Cambridge Cambridgeshire CB3 0ET United Kingdom PDCServiceDesk@bas.ac.uk https://www.bas.ac.uk/team/business-teams/information-services/uk-polar-data-centre/ information distributor application/netcdf bytes 1331692 http://ramadda.data.bas.ac.uk/repository/entry/show?entryid=baef2e88-300f-42bc-8ccb-bfdff147a492 WWW:LINK-1.0-http--link Get Data Download data download dataset Methodology: Free air gravity data was first converted into equivalent topography using the Bouguer slab formula. This initial topographic surface was used to calculate the deflection of a theoretical Moho (crust/mantle boundary) at 30 km depth and the associated isostatic gravity anomaly, following an Airy isostatic assumption (the crust has no lateral strength) and assuming densities for crust and mantle of 2670 and 3330 kgm-3 respectively, and that the initial topographic surface was in air. This calculation was done using the GMT module gravfft. The calculated isostatic gravity correction was subtracted from the initial Free air gravity anomaly. The subsequent isostatically corrected gravity anomaly was then used in place of the free air anomaly as input in the inversion procedure outlined in Jordan et al. 2020. The corrected gravity anomaly was converted to a topographic surface, using the Bouguer slab formula. The resulting gravity field was modelled, and the topographic surface updated to improve the fit between model and isostatically corrected data anomaly. This modelling and adjustment procedure was iterated three times. The output adjusted topography was compared with known bathymetric observations including offshore swath bathymetry, airborne radar over grounded ice, and four distinct sets of direct bathymetric observations beneath the Crosson and Dotson ice shelves, including from Autosub Long Range and Ran Autonomous Underwater Vehicles (AUV), from drifting depth profiling floats, and from seismic observations from the ice shelf surface. Errors between direct observations and the adjusted topography were interpolated across the region and subtracted from the adjusted topography to give the final gravity derived bathymetry for the region. Data collection: Gravity and topographic data outside the Crosson and Dotson ice shelves is the same as in Jordan et al 2020 (https://doi.org/10.5285/7803de8b-8a74-466b-888e-e8c737bf21ce). Additional bathymetric data beneath the Crosson and Dotson ice shelves was collected with Autosub Long Range and Ran Autonomous Underwater Vehicles (AUV), from drifting ORBIS EM-APEX profiling floats (Girton et al., 2019), and from 27 active seismic shot points from the ice shelf surface (Muto et al., 2024). Data quality: We estimate the recovered bathymetric data to have a standard deviation of ~70 m, based on comparison with direct observations. However, the minimum resolvable wavelength of the data is ~5 km, so it is likely that very steep, or short wavelength topography is not well represented. In such areas significantly larger errors may be expected. asNeeded completed