cf87183c-51df-4588-be73-ad0a45fea2d7 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 2025-01-30 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 Geological Long Range Inclined Asdic (GLORIA) seabed side-scan sonar raw data acquired on Charles Darwin CD37 cruise in 1989 2025-01-30 creation 2025-01-30 revision 2025-01-30 publication 2025-01-30 released 1.0 https://doi.org/10.5285/cf87183c-51df-4588-be73-ad0a45fea2d7 doi GB/NERC/BAS/PDC/02004 https://data.bas.ac.uk/ Please cite this item as: Barker, P., Livermore, R., Tomlinson, J., Woollett, R., Cunningham, A., Larter, R., Pudsey, C., & Jordan, R. (2025). Geological Long Range Inclined Asdic (GLORIA) seabed side-scan sonar raw data acquired on Charles Darwin CD37 cruise in 1989 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/cf87183c-51df-4588-be73-ad0a45fea2d7 We present here side scan sonar datasets and accompanying quicklook seabed images of the Scotia Sea acquired by a GLORIA II (Geological Long Range Inclined Asdic) side scan sonar. The GLORIA instrument was operated on the Royal Research Ship (RRS) Charles Darwin 37 (CD37) research cruise during January - April 1989. The study area was the Scotia Sea, North Scotia Ridge (NSR), South Sandwich Island, South Sandwich Arc, and West Antarctic Peninsula (WAP) continental shelf, within the broader region of the Southern Ocean. Raw data are presented in NetCDF format. These have been pre-processed from the binary pass data using the bas-gloria package (https://github.com/antarctica/bas-gloria). The data have been improved with additional metadata such as latitude, longitude and depth. In addition, "quicklook" seabed images generated from each pass file are provided as PNG images. Cruise tracks from the ship and side scan sonar are presented in CSV format. The cruise was carried out in order to gain a better understanding of the Southern Ocean with a particular focus on: - Tectonic history - Active tectonic processes - Paleoceanography - Stratigraphy - Ice dynamics during glacial intervals This project was funded by BAS under project code B6153: Scotia Sea tectonic evolution and palaeo-circulation. No credit. completed Barker, Peter British Antarctic Survey Researcher author Livermore, Roy British Antarctic Survey Researcher author Tomlinson, Jeremy British Antarctic Survey Researcher author Woollett, Richard British Antarctic Survey Researcher author Cunningham, Alexander British Antarctic Survey Researcher author Larter, Robert British Antarctic Survey Researcher author Pudsey, Carol British Antarctic Survey Researcher author Jordan, Richard British Antarctic Survey 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 EARTH SCIENCE > Oceans > Marine Geophysics EARTH SCIENCE > Oceans > Ocean Acoustics 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 Antarctica GLORIA Southern Ocean marine geology marine geophysics sidescan sonar theme South Sandwich Trench Southern Ocean Falkland Trough / Falkland Plateau Southern Ocean South Georgia and the South Sandwich Islands Southern Ocean Scotia Sea Southern Ocean Antarctic Peninsula Antarctica place Oceanographic geographical features theme GEMET - INSPIRE themes, version 1.0 2021-01-06 revision otherRestrictions no limitations to public access otherRestrictions no limitations license Open Government Licence v3.0 otherRestrictions Data supplied under Open Government Licence v3.0 otherRestrictions None url url crossReference url url dependency url url dependency url url dependency url url crossReference doi doi crossReference url url crossReference url url crossReference url url crossReference url url crossReference textTable eng utf8 geoscientificInformation oceans -74.8 0.0 -65.0 -51.5 1989-01-04 1989-04-02 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/x-hdf image/png text/csv bytes 1288490189 http://ramadda.data.bas.ac.uk/repository/entry/show?entryid=cf87183c-51df-4588-be73-ad0a45fea2d7 WWW:LINK-1.0-http--link Get Data Download data download bytes 1288490189 http://ramadda.data.bas.ac.uk/repository/entry/show?entryid=cf87183c-51df-4588-be73-ad0a45fea2d7 WWW:LINK-1.0-http--link Get Data Download data download bytes 1288490189 http://ramadda.data.bas.ac.uk/repository/entry/show?entryid=cf87183c-51df-4588-be73-ad0a45fea2d7 WWW:LINK-1.0-http--link Get Data Download data download dataset Methodology: The acquisition instrument for this dataset was GLORIA II, operated on RRS Charles Darwin The sonar towfish was 8m in length, and towed 300m behind the vessel at 50m depth. Data were collected on the RRS Charles Darwin CD37 scientific research cruise and stored on 9-track magnetic tapes, which are currently held by the British Antarctic Survey, Cambridge. Raw data were recovered from 9-track magnetic tapes in 2021. Transcription from tape was performed by Troika International/Interica. There was some data loss, due to stiction causing read errors. Heat treatment of the tapes improved data recovery at this stage. A Python package was developed by Paul Breen (BAS) to handle the GLORIA raw pass files. Conversion to NetCDF and generation of quicklooks for the GLORIA data from CD37 was performed in 2024/2025 using the package. This can be accessed here: https://github.com/antarctica/bas-gloria Decoding of the data has been performed following the structure as described in Table 1 of Searle et al. 1990. The geographic position of the GLORIA instrument relative to the ship was calculated from the CD37 cruise track by introducing a fixed time offset of 90 seconds to the datetime of the ship at each recorded coordinate point. Latitude and longitude were subsequently interpolated, to increase the frequency of the coordinate information such that this could be added to the NetCDF attribute metadata by matching the track information with passes based on the datetime field. NetCDF variable attributes: - 'units': The units of the variable's data values. For this dataset, the value is "1". - 'long_name': A long descriptive name for the variable. For this dataset, the value is "Scan Samples". - 'description': Signal intensity of sidescan sonar expressed in counts. NetCDF group attributes: - 'pass_number': Pass number (units: 1) - ''scan_number': Scan number (units: 1) - 'hour_mark_flag': Flag for hour mark (units: 1) - 'slant_range_correction_code': Slant-range correction code (units: 1) - 'zero_flag': Binary zero (units: 1) - 'pulse_repetition_period': Pulse repetition period (units: second) - 'vehicle_heading': Vehicle heading (units: degree) - 'year': Year (units: year) - 'edge_mark_start': Unsigned 16 bit integer (units: 1) - 'edge_mark_end': Unsigned 16 bit integer (units: 1) - 'julian_day': Julian day (units: julian day) - 'hours'''': Hours (units: hour) - 'minutes': Minutes (units: minute) - 'seconds'': Seconds (units: second) - 'checksum': Checksum (units: 1) - 'unused': Unused (units: 1) - 'latitude': Latitude of GLORIA (unit: degree_east) - 'longitude': Longitude of GLORIA (unit: degree_north) - 'depth': Depth of the seabed from IBCSO at the location of GLORIA side scan sonar(unit: meters) The cruise track CSV contains the fields: - time - longitude (degree_east) - latitude (degree_north) The GLORIA track contains the fields: - time_gloria - longitude (degree_east) - latitude (degree_north) - depth_IBCSO_v2 (m) Data collection: GLORIA (Geological Long-Range Inclined Asdic) is a side-scan sonar instrument which acquires acoustic images of the seafloor. Side-scan sonar allows to get an image of the seafloor through an active acoustic swath mapping method in which side-mounted transducers, suspended from a towed object, generate an acoustic signal which is reflected by the seabed and received by the transducer after a delay which is a function of the signal roundtrip travel time through the water column. The intensity of this returned signal enables the differentiation of seafloor features and can be processed into an image. This "image" represents how the sound produced by the sonar instrument interacts with the seabed interface. As part of the CD37 cruise, the system consisted of two sonar transducers, each 5.3m in length and containing 60 elements over 2 rows. The transducers were inclined 20 degrees to vertical, directed to port and starboard respectively. The port transducer operated at 6.8kHz frequency and the starboard transducer at 6.3kHz frequency. The signal was a 100Hz swept frequency chirp, with a peak electric power of 5kW. The pulse frequency was one per 30s (a Pulse Repetition Period of 30-s), and pulse duration was 2 seconds. The range of GLORIA II is approximately 5 times the water depth, up to a maximum range of 22.5km on each side (i.e. port and starboard). This amounts to a total swath width of 45km. GPS data was provided by a Trimble 4000 Locator and provides ship positioning information. The software used to convert and process the GLORIA CD37 data are as follows: bas-gloria package: https://github.com/antarctica/bas-gloria Data quality: In the initial data recovery, PASS245 was long and PASS246 was missed. This was determined to be caused by a reading error, resulting in concatenation of consecutive data from PASS246 to PASS245. These passes were then read from tape separately, and are now considered complete. In the recovered raw data, some passes were missing: PASS039, PASS040 and PASS231. Copies of these data held at BODC were provided in CDF format, which were converted to NetCDF. These passes are now considered complete. As the CDF files did not contain data for the slant range correction code, zero flag, hour mark flag and unused attributes (which were determined to be non-significant in the recovered raw data), a NaN value of 9999 has been used in the converted files for these passes. In addition, it is to be noted that PASS038, PASS227 and PASS236 are partially complete, To get the latitude and longitude of GLORIA related to the ship, a fixed 90 second time offset was added to the ship track datetime to account for tow distance of the GLORIA instrument behind the ship (the output of this was the GLORIA track CSV). The latitude and longitude of the GLORIA track was then interpolated to provide the value of these coordinates at the original datetime of the ship track. This was done in order to map geographic information to the timestamps within the netCDF metadata. Interpolation on the latitude and longitude fields from ship track data was done with the Pandas Python library. Depth values within the NetCDF file metadata are provided by the International Bathymetric Chart of the Southern Ocean (IBCSO) version 2. Due to the resolution of IBCSO, the depth in the GLORIA NetCDF metadata is provided with a horizontal resolution of 500x500m, leading to some positive values close to coastline areas. asNeeded completed