Raw bathymetry data collected from a hull-mounted Kongsberg EM122 multibeam echosounder during RRS Sir David Attenborough SD041 cruise, 2024
GB/NERC/BAS/PDC/02222
Abstract:
Presented here is the raw multibeam bathymetry data acquired from 2024-07-23 to 2024-08-25 as part of RRS Sir David Attenborough SD041 research cruise also referred to as KANG-GLAC. Bathymetry data were collected using a hull-mounted Kongsberg EM122 multibeam echo-sounder. Data are provided in raw Kongsberg format (.all and .wcd for water column data). Data are unprocessed and therefore may contain incorrect depth measurements without further processing. Partially processed data are available on request from the Polar Data Centre.
KANG-GLAC is a NERC funded project to investigate how the accelerating decay of the Greenland Ice Sheet will progress with climate change, and to better understand the knock-on effects this will have on ocean circulation and marine productivity. This work was funded by Natural Environment Research Council (NERC) grant NE/V006509/1.
Citation:
O'Cofaigh, C., Hogan, K., Howe, J., Roberts, D., Donate, V., Fremand, A., Hunt, M., Jenkins, H., Larter, R., Metcalfe, J., & Strandlod, F. (2026). Raw bathymetry data collected from a hull-mounted Kongsberg EM122 multibeam echosounder during RRS Sir David Attenborough SD041 cruise, 2024 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/9b14a4ee-96ad-4520-97d7-3b3b2821ab74
Access Data
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License
| Access: | None |
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| Use: | This data is covered by a UK Open Government Licence (http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/) By downloading this data the user acknowledges that they agree with the NERC data policy (http://www.nerc.ac.uk/research/sites/data/policy.asp), and the following conditions: 1. To cite the data, and 2. The user recognises the limitations of the data and will not use this data for navigation purposes. Use of the data is at the users' own risk, and there is no warranty as to the quality or accuracy of any data, or the fitness of the data for your intended use. The data are not necessarily fully quality assured and cannot be expected to be free from measurement uncertainty, systematic biases, or errors of interpretation or analysis, and may include inaccuracies in error margins quoted with the data. NOT TO BE USED FOR NAVIGATION |
Basic Information
| Creation Date: | 2026-06-12 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
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| Parameters: |
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Additional Information
| Reference: | Cruise report: https://www.bodc.ac.uk/resources/inventories/cruise_inventory/report/18764/ | |
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| Quality: | The raw data are presented here. The data have not been corrected for vertical datum and no tide model was applied. No quality check has been performed. Data are not to be used for navigation. On 10th August at 09:39 UTC, the two Global Navigation Satellite System (GNSS) systems (Seapath 1 and Seapath 2) were rebooted unexpectedly by the bridge. The EM122 system crashed as it had lost both location and time information. While the location was back after the first EM122 reboot, the Seapath drop out led to several time issues which unfortunately were not picked up right away. At the time of the first restart, from ~10:00 to 15:34 UTC, the date/time set in the PU was one day and several hours before the expected date/time.File numbers 170 to 175 from survey SD041_b thus show an approximately 31-hour difference from the real UTC date time. At 15:34 UTC on 10/08/2024, the time was set right after a restart of the computer, but the date of the Processing Unit (PU) was still set one day early: 09/08/2024 instead of 10/08/2024. Files 176 (file 175 does not exist) to 202 of survey SD041_b are thus affected by a 24-hour difference between their time stamps and the UTC date/time. The issue was fixed on 11/08/2024 at 20:46 UTC. Because of this issue, we have several datasets from different locations collected at the same time. |
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| Lineage/Methodology: | The multibeam bathymetry data presented here have been acquired from 2024-07-23 to 2024-08-25 as part of RRS Sir David Attenborough cruise SD041. RRS Sir David Attenborough is fitted with a hull-mounted Kongsberg EM122 multibeam echo sounder with 1 degree x 1 degree acoustic beam widths. Multibeam bathymetry data were collected throughout the cruise, primarily to map unsurveyed areas, provide bathymetric characterisation of the local surroundings and identify suitable deployments sites. The deep-water EM122 multibeam echosounder generally performed well throughout SD041 and in most conditions. We can however note noisier data at slow speed (2-5 knots) when there is a bit of swell. This is the case for example during some MOCNESS deployments. This is almost certainly a result of aerated surface water being pushed under the transducers and reducing the signal strength of the transmitted sound. Due to regulations and technical issues, most of the data were acquired with an average ship speed of 5 knots. The data were acquired using the Seafloor Information System (SIS) software - version 4.3.2. The installation parameters were set up following the information from the Anko Maritime AS (2020) reference survey as follows: TX transducer: X = 21.457 m, Y= -0.711 m, Z = 7.975 m, Roll: 0.04 deg, Pitch = -0.02 deg, Heading = 0.01 deg RX transducer: X = 16.425 m, Y = -0.006 m, Z = 8.004 m, Roll: -0.06 deg, Pitch =-0.25 deg, Heading = 0.08 deg No calibration was undertaken on the EM122 during the cruise due to time constraints. The last calibration was undertaken on 27-28/08/2022 to the north of the Butt of Lewis (Northwest Scotland). These values have been added into SIS in the offset angle section of the installation parameters. The following angular offsets from the previous calibration were used (all values given in degrees): Roll: 0.11 Pitch =0.00 Heading =-0.1 The EM122 was always operated in external trigger mode via K-sync allowing multiple acoustic instruments to be operated at the same time. The multibeam system was monitored and the 'angular coverage', 'depth', 'ping mode' and 'mammal protection' parameters changed regularly to adapt to the water depth and sea conditions. In bad weather, to increase the quality of the data, the beam angles were reduced and the power set to maximum. The dual swath mode was enabled for the EM122 and set to 'DYNAMIC'. This means that the alongship angle between the two transmit fans is determined based on vessel speed, ping rate and depth, in order to provide uniform alongship sampling of the seafloor. ** Sound velocity ** Sound velocity corrections are essential for accurate bathymetric depths.The multibeam systems have an input for a surface sound velocity value at the transducer and sound velocity profiles were updated regularly. Profiles were obtained from CTD casts throughout SD041 and used as the primary input for sound velocity. Surface sound velocity was also obtained from a Valeport miniSVP sensor installed in the uncontaminated seawater system. These values were monitored and when possible the profile was updated with new CTD values. In icy conditions, it is to be noted that the inlet was flushed and not providing accurate data. ** Survey information ** SD041_a - Transit from UK up to Icelandic EEZ waters - no data aquired. SD041_b - Greenlandic waters, mooring site, Kangerlussuaq Trough SD041_c - 3-Miippugut Fjord SD041_d - Transit from 3-Miippugut fjord to Kivioq fjord, Kivioq fjord and bay in front of Rosenborg Gletcher On a few occasions, mainly linked to acquisition close to glaciers, water column data were acquired to better map ice fronts. |
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PROJECT HOME PAGE:
- https://storymaps.arcgis.com/stories/085f32c8562d479f86ad27305b9c699e
- https://www.bas.ac.uk/project/kang-glac/
REFERENCE MATERIALS:
RELATED DATA SET METADATA:
- https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/02223
- https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/02224
- https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/02225
- https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/02226
SOFTWARE PACKAGES:
Extent
| Temporal Coverage: | |
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| Start Date | 2024-07-23 |
| End Date | 2024-08-25 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | 64.99462 |
| Northernmost | 68.46745 |
| Longitude | |
| Westernmost | -33.2628 |
| Easternmost | -28.7968 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | 20m |
| Max Depth | 2000m |
| Location: | |
| Location | Arctic Ocean |
| Detailed Location | N/A |
| Location | Greenland |
| Detailed Location | N/A |
Instrumentation
| Sensor(s): |
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| Source(s): |
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| Data Collection: | Data collected on board RRS Sir David Attenborough using a Kongsberg EM122 multibeam echosounder using SIS software (version 4.3.2) . |
Storage
| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 44 GB |
| Distribution Format | N/A |
| Fees | N/A |
| Data Storage: | This dataset consists of bathymetry data collected as part of 3 surveys: - SD041_b: 558 files (54 .wcd and 504 .all files) ~34 GB - SD041_c: 101 .all files ~6.8 GB - SD041_d: 93 files (4 .wcd and 89 .all files) ~5.9 GB |