Rowley Shelf 3D seismic derived bathymetry compilation (20230005C)

Maintenance and Update Frequency: notPlanned | Statement: AusSeabed follows the recommended processing methodology as prescribed by the AusSeabed Multibeam Guidelines. Please note that certain products are subject to routine update (e.g. resolution, coverage, temporal variation, guidelines/best practice). The client is advised to refer to the latest version of all documents and products for the mostup-to-date material. For eCat records the version is expressed in the record title whilst products incorporate date of production as per AusSeabed’s file naming convention. The detailed workflow is presented in Lebrec, 2023 (Lebrec, U., Paumard, V., De Reau, C., O’Leary, M.J., and Lang S.C., 2023, Seismic-derived bathymetry data asset, Australia. and the Individual processing steps performed on each survey are reported in the supplementary spreadsheet (see attached zip file). It can be summarized as follow: 1. Data Collection. All publicly available 3D seismic surveys within the area of interest, including PSTM SGY and P190 files were sourced from Nopims and QA/QC. 2. SGY processing. The first reflector was extracted using PaleoScan™ software from each SGY file. The resulting surfaces are in time domain. 3. P190 Filtering. Navigation files were filtered to extract depth values at the vessel echo-sounder location. If unavailable, the vessel reference point was selected instead. Depth values within P190 files are in metres, but typically obtained using constant velocities. As such, whenever velocities are specified, depth values were converted back to time for further calibration. 4. Time\depth conversion. All depth values are converted from time to depth using site-specific synthetic velocity profiles derived from WOA2018 salinity and temperature databases using Doris software. 5. Gridding. Individual surveys were gridded using inverse distance weight algorithm, and exported as 32-bit floating point Geotif. The bin size is defined as the square root of the average area occupied by a point. 6. Datum Calibration. All grids and point clouds were converted to WGS84 and reduced to EGM2008. To do so, datasets were reduced to LAT using AHO depth sounding as calibration points before being converted to EGM2008 using AusCoastVDT software. It should be noted that LAT and EGM2008 are regarded as equivalent for areas beyond AusCoastVDT coverage, that are typically in water depth of more than 400m (Fig. 2). | Purpose Bathymetry Compilation | The Rowley Shelf 3D seismic derive