Sub-bottom profile data collected from a hull-mounted Kongsberg Marine TOPAS (PS18) profiler during RRS Sir David Attenborough SD041 cruise, 2024
GB/NERC/BAS/PDC/02226
Abstract:
We present here the raw sub-bottom profile data acquired from 2024-07-19 to 2024-08-25 as part of RRS Sir David Attenborough SD041 research cruise also referred to as KANG-GLAC. Sub-bottom profile data were collected using a hull-mounted Kongsberg Marine TOPAS (PS18) profiler. Data is provided in SEG-Y.
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:
Hogan, K., O'Cofaigh, C., Howe, J., Roberts, D., Donate, V., Fremand, A., Hunt, M., Jenkins, H., Larter, R., Metcalfe, J., & Strandlod, F. (2026). Sub-bottom profile data collected from a hull-mounted Kongsberg Marine TOPAS (PS18) profiler during RRS Sir David Attenborough SD041 cruise, 2024 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/73f50a04-0a2a-4e69-bb4e-ee6fffa4c026
Access Data
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License
| Access: | None |
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| Use: | This data is governed by the NERC data policy http://www.nerc.ac.uk/research/sites/data/policy/ and supplied under Open Government Licence v.3 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ |
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: | We present here the raw data. Only a visual check was performed during the cruise. | |
| Lineage/Methodology: | The multibeam bathymetry data presented here have been acquired from 2024-07-19 to 2024-08-25 as part of RRS Sir David Attenborough cruise SD041. The TOPAS equipment was operated primarily using Kongsberg TOPAS version 3.3 software (very rarely version 3.2). The TOPAS sub-bottom profiler was used in conjunction with the multibeam echo sounders as an essential tool for identifying sediment core sites and was therefore used extensively during the cruise. To avoid interferences with the other acoustic instruments (ADCP, EK80, EM122 and EM712), the system was running through an external trigger managed by K-SYNC. ** Acquisition ** Before starting each period of transmission on these systems marine mammal watches were conducted from the Bridge following NERC Marine Environment Interaction Policy by members of the scientific party who had completed JNCC-approved training courses. On completion of marine mammal watches TOPAS transmission was started with the "Whale warning" option enabled (in the Acquisition - Transmitter menu) with a ramp time of 15 minutes starting from a power level at least 20 dB below the target power level specified for normal running. TOPAS transmission was first started at 16:47 UTC on 19th July 2024. The system was then stopped before entering the Icelandic EEZ at 19:58UTC on 20th July 2024 and turned back on when entering the Greenlandic waters at 10:20UTC on 23rd July. From then, the system was run continuously apart from the multiple instances where it stopped for unknown reasons but rapidly restarted by the watchkeeper. The list of parameters used are summarised below: * TRANSMITTER Transmit mode: Normal Trigger mode: Internal or external Ping interval: Managed by K-sync with a minimum ping interval of 1s in shallow water Pulse form: Chirp (LFM) Start frequency (kHz): 1.5 Stop frequency (kHz): 5 Chirp length: 10 Output level (dB) : Between -9 and 0 depending on depth and environmental noise HRP stabilization: On Beam control: Manual Transducer sound speed (m/s): Adapted automatically or manually from sound probe. * RECEIVER Delay control: Manual Master trig delay (ms): Set manually depending on depth Delay offset (ms): -35 to 0 Sample rate: 32 Trace length (ms): 400 HP-filter (kHz): 2.0 Bottom tracker: ON ** Performance ** The main problem with TOPAS was encountered on 10/08/2024. After a bridge reboot of Seapath between 09:36 and 09:49 UTC, TOPAS crashed and was not responding or pinging anymore. It has been only possible to restart TOPAS after 8 hours spent trying to fix the system. During that time, all the fuses were checked, the cables disconnected and reconnected, and the software uninstalled and reinstalled (see AME report for further information). In addition, it is to be noted that the system stopped at more or less regular intervals (on some days every 30-60min) for no apparent reason. It was usually restarted again by rebooting the computer, mostly by an operating system restart but on a few occasions with a hard reboot of the server. ** Data format ** The raw data are made available here. No data processing has been applied other than conversion from raw format to SEG-Y. The conversion has been done using the TOPAS MMI 3.2 software using exporting the 'processed' SEG-Y. ** Note on latitude and longitude encoding in the SEG-Y file ** The survey navigation is encoded in the SEG-Y trace headers using the source_coordinate_x and source_coordinate_y fields. Coordinates are recorded as scaled integers representing arc-seconds (coordinate_units = 2). A coordinate scalar of -1000 is specified, meaning the stored values must be divided by 1000 to recover the true arc-second values. These are then converted to geographic latitude and longitude in decimal degrees by dividing by 3600. |
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Extent
| Temporal Coverage: | |
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| Start Date | 2024-08-19 |
| 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
| Source(s): |
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| Data Collection: | Data collected on board RRS Sir David Attenborough using a Kongsberg Marine PS18 sub-bottom profiler with the associated TOPAS software (version 3.3) . |
Storage
| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 21 GB |
| Distribution Format | N/A |
| Fees | N/A |
| Data Storage: | This dataset consists of 234 SEGY files (21 GB) and a quicklook PDF file . |