Elizabeth and Middleton Reef bathymetry survey (GA4848)

Brief description

This resource includes bathymetry data for Elizabeth and Middleton Reef within Lord Howe Marine Park collected by Geoscience Australia during the period 31 January to 6 February 2020 on the Australian Maritime College vessel, TV Bluefin.
The survey was undertaken as a collaborative project funded through the National Environmental Science Program Marine Biodiversity Hub, with the Institute for Marine & Antarctic Studies (University of Tasmania), NSW Department of Primary Industries, University of Sydney (Centre for Field Robotics) and Parks Australia.
The purpose of the survey was to collect baseline information for benthic habitats within the National Park Zone (Middleton Reef) and Recreational Use Zone (Elizabeth Reef) of the marine park.
These data will support ongoing environmental monitoring within the Temperate East Marine Park Network as part of the 10-year management plan (2018-2028).
Data acquisition for the project included seabed mapping using multibeam sonar (Kongsberg EM 2040C HD, 300 kHz), seabed imagery acquisition by Autonomous Underwater Vehicle (AUV Sirius), sediment samples (grab) and imagery of demersal fish communities by baited remote underwater video (BRUV).
This dataset comprises two bathymetry grids derived from multibeam sonar data gridded at 5 m spatial resolution, covering a combined area of 312 km2 including the transit.
A detailed report on the survey is provided in: Carroll, A et al. 2020. Australian Marine Park Baseline and Monitoring Survey: Post Survey Report, Middleton and Elizabeth Reefs, Lord Howe Marine Park. Report to the National Environmental Science Program, Marine Biodiversity Hub.
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 GA4848.
The Chief scientist onboard was Dr. Andrew Carroll
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:
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 the 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 two 32 bit Geotif format at 5 m resolution referenced to ellipsoid and to mean sea level.

Notes

Purpose
bathymetry survey