Northern Depths of the Great Barrier Reef bathymetry survey (FK200930/GA4866)

Brief description

This resource includes bathymetry data acquired during the Northern Depths of the Great Barrier Reef survey on RV Falkor using its Kongsberg EM302 multibeam sonar system. The EM710 data acquired on this survey will be included in a future release. The primary objective of the survey was to explore the Cape York Peninsula region, through geophysical mapping of the shelf edge and continental slope adjacent to the barrier reefs and around the seven detached reefs lying north of Cape Weymouth, including within the large Wreck Bay. The offshore Cape York area is considered a frontier marine region with very little multibeam data collected previously in this far northern section of the Great Barrier Reef. The survey aimed to reveal the full inventory of submarine canyons, drowned reefs and any other significant seabed features in the region. A secondary objective was to conduct geophysical mapping of the Swain slide, an underwater landslide on the slope adjacent to the Swain Reefs in the southern Great Barrier Reef, with a headscarp about 10 km wide and a debris field extending ~20 km from the headscarp. The mapping aimed to reveal the full extent of the debris field and nature of the debris material proximal to the headscarp. Another objective was to conduct geophysical mapping around the steeper slopes around reefs in the eastern Coral Sea Marine Park, including the Saumarez, Frederick, Kenn, Wreck and Cato Reefs. The mapping aimed to fill data gaps between existing airborne LIDAR bathymetry over the shallow reefs and previously collected multibeam data around the steeper flanks. To achieve these objectives, the survey extended over 47 days, leaving Brisbane, Australia on September 30, 2020 and returning to Brisbane, Australia on November 17, 2020. The voyage was split into three legs, with port calls made at Cairns and Horn Island in the Torres Strait. Geophysical mapping involved the use of both Kongsberg EM302 and EM710 multibeam systems on the RV Falkor, typically operated in Dual Swath mode. In depths deeper than ~1200 m, the EM710 was turned off. Backscatter and water column data were also collected on both multibeam systems. This V1 dataset contains two 64m resolution 32-bit geotiff files of the FK200930 survey area produced from the processed EM302 only bathymetry data. This dataset is not to be used for navigational purposes. This dataset is published with the permission of the CEO, Geoscience Australia.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: While AusSeabed aims to publish data to the level of adherence based on the requirements stated in the AusSeabed multibeam guidelines (version 1), we will also publish interim products (version 0) that are currently available, but have not yet been standardised (version 1). Users should be aware that V1 products will always supersede V0 products. This is a V1 product for GA4866. The Chief scientist onboard was Dr Robin Beaman and Ms. Mardi McNeil This dataset was produced using CARIS HIPS/SIPS v.11.3.7 For any metadata questions, please download the Metadata.txt file with the dataset. Processing methodology: Following the CARIS HIPS/SIPS workflow, 1. A vessel configuration file was created where the co-ordinates of the motion sensor, DGPS antenna and patch test offsets were recorded. 2. A new project was created and the vessel configuration file attached to the project file. 3. The raw swath sonar data files, in raw.all format, for each line was imported into the project and the vessel information assigned to the data. Ellipsoid vertical reference system is our first preference and when not available or possible to do so, a tidal zone data is the next preference to be applied to the data 4. The motion sensor, DGPS and heading data were cleaned using a filter that averaged adjacent data to remove artefacts. 5. Sound velocity profiles data for each block of data were attached to the corresponding raw swath sonar data files. 6. A new blank fieldsheet area was defined that specified the geographic area of study and the co-ordinate system used. 7. The data was cleaned by applying several filters that removed any spikes in the data using user defined threshold values. 8. Data were inspected visually for each line where artifacts and noisy data had not removed by the filtering process. 9. Remaining spikes were removed manually using the swath and subset editor modules. 10. All the data, i.e. bathymetric sounding and ancillary data, were merged to produce the final processed data file. 11. A weighted grid of the processed data was then created. 12. Independent velocity corrections were performed where velocity artefacts were observed. 13. The final processed grid was exported as a 32 bit Geotif format at 64 m resolution

Notes

Purpose
bathymetry survey