High Resolution Bathymetry Grids - Caswell Sub-basin, Browse Basin Marine Survey (GA0345/GA0346/TAN1411)

Brief description

Geoscience Australia conducted a marine survey (GA-0345 andGA-0346 /TAN1411) in Commonwealth waters of the north-eastern Browse Basin (Caswell Sub-basin) between 9 October and 9 November 2014. The purpose of the survey was to collect pre-competitive marine data to support a CO2 storage assessment in the Browse Basin, with particular emphasis on the integrity of seals overlying select CO2 storage plays. Data acquisition was undertaken as part of the National CO2 Infrastructure Plan (NCIP), administered by the Department of Industry and Science. The survey was conducted in 3 Legs aboard the New Geoscience Australia (GA) conducted a marine survey (GA0345/GA0346/TAN1411) of the north-eastern Browse Basin (Caswell Sub-basin) between 9 October and 9 November 2014 to acquire seabed and shallow geological information to support an assessment of the CO2 storage potential of the basin. The survey, undertaken as part of the Department of Industry and Science's National CO2 Infrastructure Plan (NCIP), aimed to identify and characterise indicators of natural hydrocarbon or fluid seepage that may indicate compromised seal integrity in the region. The survey was conducted in three legs aboard the New Zealand research vessel RV Tangaroa, and included scientists and technical staff from GA, the NZ National Institute of Water and Atmospheric Research Ltd. (NIWA) and Fugro Survey Pty Ltd. Shipboard data (survey ID GA0345) collected included multibeam sonar bathymetry and backscatter over 12 areas (A1, A2, A3, A4, A6b, A7, A8, B1, C1, C2b, F1, M1) totalling 455 km2 in water depths ranging from 90 - 430 m, and 611 km of sub-bottom profile lines. Seabed samples were collected from 48 stations and included 99 Smith-McIntyre grabs and 41 piston cores. An Autonomous Underwater Vehicle (AUV) (survey ID GA0346) collected higher-resolution multibeam sonar bathymetry and backscatter data, totalling 7.7 km2, along with 71 line km of side scan sonar, underwater camera and sub-bottom profile data. Twenty two Remotely Operated Vehicle (ROV) missions collected 31 hours of underwater video, 657 still images, eight grabs and one core. This catalogue entry refers to bathymetry data acquired during survey GA0345/GA0346/TAN1411.

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Maintenance and Update Frequency: asNeeded

Statement: The Browse Basin Marine Survey 2014, GA-0345 TAN1411 was acquired by Geoscience Australia onboard the RV Tangaroa from the 9th of October to the 12th of November 2014. The Chief scientist onboard was Dr. Chris Nicholson. This dataset was acquired onboard by Justy Siwabessy and further processing was conducted in the office by Michele Spinoccia, using CARIS HIPS & SIPS ver 7.1.2. 1. First a vessel configuration file was created where the co-ordinates of the motion sensor and DGPS antenna and patch test offsets were recorded. 2. A new project was then created and the vessel configuration file was attached to the project file. 3. The raw swath sonar data, in raw.all format, for each line was then imported into the project and the vessel information assigned to the data. 4. The motion sensor, DGPS and heading data were then cleaned using a filter that averaged adjacent data to remove artefacts. 5. Different sound velocity profiles data for each block were attached to the corresponding raw swath sonar data files to correct the depths for changes in the speed of sound through the water column. 6. Then a new blank field area was defined that specified the geographic area of study and the co-ordinate system used. The co-ordinates for the study areas were WGS84 UTM-52S and 51S. 7. The data was cleaned by applying several filters that removed any remaining spikes in the bathymetry data using user defined threshold values. A visual inspection of the data for each line was then undertaken where artefacts and noisy data not removed by the filtering process were removed manually using Swath and subset editors modules of the Caris HIPS/SIPS software. 8. All the data for each bathymetric, motion sensor, DGPS, heading, tide and sound velocity profile data were merged to produce the final processed data file. A weighted grid of the processed data was then created for each Block. In GA the tide was applied to the grid to correct for tidal variations and velocity corrections were performed to correct for different artefacts and mismatches. 9. The processed data was finally exported as grids soundings or false colored images for presentation and reporting and as final processed data in ASCII XYZ, KML and geotif formats of 1, 2 and 7m resolution. 10-Using CARIS Base editor 4.0 the grids were exported as ESRI ASCII grid, then imported into ARC catalogue/info to create a raster file for the entire survey.