XYZ multibeam bathymetric grids of the Bremer Sub-Basin

Full description

This is a compilation of all the processed multibeam bathymetric data that Geoscience Australia holds in its database for the Bremer Sub-Basin. The location of the sub-basin lies in deep water off the southwest margin of WA between Albany and Esperance at the western end of the Great Australian Bight.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: The data was acquired onboard three research vessels through twelve surveys as following: # Survey Name Vessel Name Multibeam System Institution Start Date End Date Start Port End Port 1 GA-0157_Adedav N/O Latalante EM120D (12 kHz) EM950 (95kHz) GA/IFREMER 3/04/1994 15/04/1994 Adelaide SW Timor 2 GA-0208_Margau (MD110) RV Marion Dufresne TSM 5256 (12 kHz) GA/IPEV 29/04/1998 29/05/1998 Fremantle Fremantle 3 GA-0236_Auscan1 (MD130) RV Marion Dufresne TSM 5256 (12 kHz) GA/IPEV 23/01/2003 16/02/2003 Fremantle Hobart 4 GA-0245_Auscan2 (MD131) RV Marion Dufresne TSM 5256 (12 kHz) GA/IPEV 18/02/2003 4/03/2003 Hobart Fremantle 5 GA-0265_Bremer (SS03/2004)RV Southern Surveyor EM300 (30 kHz) CSIRO 9/02/2004 9/03/2004 Fremantle Hobart 6 GA-0296_WA Bio1(SS07/2005)RV Southern Surveyor EM300 (30 kHz) CSIRO 21/07/2005 15/08/2005 Dampier Fremantle 7 GA-2390 WA Bio2 (SS10/2005)RV Southern Surveyor EM300 (30 kHz) CSIRO 17/11/2005 14/12/2005 Fremantle Dampier 8 GA-2396_Ausfair Transit (VT82)RV Marion Dufresne TSM 5256 (12 kHz)GA/IPEV 27/02/2006 6/03/2006 Sydney Albany 9 GA-2400_Leuwin (SS04/2006) RV Southern Surveyor EM300 (30 kHz) CSIRO 9/04/2006 30/04/2006 Esperance Fremantle 10 GA-2433_Hobart_Fremantle(SST03/2007) RV Southern Surveyor EM300 (30 kHz) CSIRO 30/04/2007 9/05/2007 Hobart Fremantle 11 GA-4304_Hobart_Broome Transit (SST01/2010) RV Southern Surveyor EM300 (30 kHz) CSIRO 29/03/2010 13/04/2010 Hobart Broome 12 GA-4324_Fremantle-Hobart Transit (SST02/2010) RV Southern Surveyor EM300 (30 kHz) CSIRO 10/08/2010 18/08/2010 Fremantle Hobart The data was converted into the bathymetric processing software CARIS HIPS & SIPS using the following procedures: 1- A vessel configuration file was created for RV Southern_Surveyor, NO_Latalante and RV_Marion Dufrene, where the co-ordinates of the motion sensor and DGPS antenna and patch test offsets were recorded. 2- The raw swath sonar data, in raw.all format for RV_Southern_Surveyor, mb75 for L-Atalante and Marion Dufresne, for each line was then imported into the project and the vessel information assigned to the data. 3- The motion sensor, DGPS and heading data were then cleaned using a filter that averaged adjacent data to remove artefacts. 4- 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. 5- Then a new blank field area was defined that specified the geographic area of study and the co-ordinate system used. Two grids were created for the Bremer sub-basin, Bremer1 and Bremer2. The co-ordinates for the study areas were WGS84 UTM-50S for Bremer1 sub basin, and WGS84UTM51 for Bremer2 sub-basin. 6- 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. 7- 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. 8- The processed data was finally exported as final processed data in ASCII XYZ file format with header information, exported as Easting and Northing and negative depth, projected in UTM50 and 51 and WGS84 as datum. 9- 8 ESRI Arc Info grids were created from those bathymetric ASCII XYZ grids. 10- Geotifs were created for those grids at 50 and 100m resolution and an addition geotif of the whole Bremer basin with a depth legend.