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.
Multibeam swath bathymetry data collected onboard ship during multiple cruises in the Southern Ocean between Oct 2002 and Jan 2006.
The South Georgia Bathymetric Dataset (SGBD) is a continuous grid at 150m resolution of the sea floor around South Georgia. Available in a number of formats and projections, the dataset has been compiled from eleven different data sources.
We present a new bathymetric compilation around Ascension Island here defined by the following bounding box: 14.57 to 14.17 W, 8.12 to 7.75 S. This bathymetry grid was compiled from a variety of multibeam swath bathymetry data acquired during 4 different cruises (see lineage). The data is available as a grid of approximately 50 m resolution in two different formats: a GMT-compatible (2-D) NetCDF and Arc/Info and ArcView ASCII grid format using geographic coordinates on the WGS84 datum. Funding was provided by NERC grants NE/J023051/1 and NE/J020303/1
We present a new bathymetric compilation of the South Shetland Islands here defined by the following bounding box: 63 to 53.3 W, 63.5 to 60.5 S. This bathymetry grid was compiled from a variety of multibeam swath bathymetry data acquired during 76 different cruises (see lineage). The data is available as a grid of approximately 100 m resolution in two different formats: a GMT-compatible (2-D) NetCDF and Arc/Info and ArcView ASCII grid format using geographic coordinates on the WGS84 datum.
We present a bathymetric compilation of Ryder Bay here defined by the following bounding box: 68.48 to 68W, 67.7 to 67.46S. This bathymetry grid was compiled from a variety of multibeam swath bathymetry data acquired during 18 different cruises (see lineage) undertaken by the RRS James Clark Ross. The data is available as a grid of 0.0005 degrees resolution in two different formats: a GMT-compatible (2-D) NetCDF and Arc/Info and ArcView ASCII grid format using geographic coordinates on the WGS84 datum.
We present two new gridded bathymetric compilations of the Orkney Passage, Scotia Sea here defined by the following bounding boxes: 39.1 to 39.6 W, 60.55 to 60.7 S and 41.7 to 42.6 W, 60.45 to 60.8 S. These bathymetry grids were compiled from a variety of multibeam swath bathymetry data acquired during 12 different cruises (see lineage). The data is available as grids of 50 m resolution in a GMT-compatible (2-D) NetCDF format using geographic coordinates on the WGS84 datum. This grid was compiled in support of the ongoing monitoring efforts in and around Orkney Passage as part of the Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA) programme and preceding BAS NC projects, and the Dynamics of the Orkney Passage Outflow (DynOPO) project. Funding was provided by the NERC grants NE/K012843/1 and NE/N018095/1 as well as national capability
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 new 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 and onshore airborne radio-echo depth sounding data in the surrounding area. Ice shelves mask the critical link between the ocean and cryosphere systems, and hence accurate sub ice shelf bathymetry is critical for generating reliable models of future ice sheet change. Included in the data release is the input free air gravity data, constraining bathymetry/sub-ice topography, and output gravity derived bathymetry. This work was funded by the British Antarctic Survey core program (Geology and Geophysics team), in support of the joint Natural Environment Research Council (NERC)/ National Science Foundation (NSF) International Thwaites Glacier Collaboration (ITGC). Additional specific support came from NERC Grants: NE/S006664/1 and NE/S006419/1, and NSF Grants: NSF1842064, NSFPLR-NERC-1738942, NSFPLR-NERC-1738992 and NSFPLR-NERC-1739003.
Bottom topography - assessed by swath bathymetry - of the Southern Ocean collected aboard the James Clark Ross (JR145) during the 2005-2006 field season. Bathymetry data was collected to assess its influence on dispersal and gene flow in two Antarctic fishes (Champsocephalus gunnari and Notothenia rossii). Data was collected in the Southern Ocean from Elephant Island, Deception Island, the South Orkney Islands, King George (Potter Cove) and Signy (Borge Bay).
Ship underway data collected aboard the James Clark Ross during cruise no JR158 in 2007. Includes data from navigation and vessel-mounted ADCP (Acoustic Doppler Current Profilers). On the ship the position and observed data were interpolated to five-second records to merge the navigation with the underway data. These one-minute averages are averages over 12 of the interpolated points.