Davis Coastal Seabed Mapping Survey, Antarctica (GA4301 / AAS2201 / HI468) - High Resolution Bathymetry Grids

Brief description

The Davis Coastal Seabed Mapping Survey, Antarctica (GA-4301 / AAS2201 / HI468) was acquired by the Australian Antarctic Division workboat Howard Burton during February-March 2010 as a component of Australian Antarctic Science (AAS) Project 2201 - Natural Variability and Human Induced Change on Antarctic Nearshore Marine Benthic Communities. The survey was undertaken as a collaboration between Geoscience Australia, the Australian Antarctic Division and the Australian Hydrographic Service (Royal Australian Navy). The objectives were to provide multibeam bathymetry and backscatter of the coastal region of the Vestfold Hills around Davis Station, Antarctica, to aid the understanding of sea bed character, benthic habitats, provide a basis for hydrodynamic modelling of water movement around Davis, and to update and extend the navigational charts of the region.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: The Coastal Seabed Mapping Survey, GA-4301 AAS2201 was acquired by Geoscience Australia onboard the AAD Workboat Howard Burton from the 15th of February to the 12th of March 2010. The Chief scientist onboard was Dr. Philip O'Brien (GA). This dataset was acquired by Ian Atkinson and processed onboard by Philip O'Brien, Ross Bowden and Jade Paddison 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 artifacts. 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-43S. 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 artifacts 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 artifacts and mismatches. The tidal datum used onboard was LAT (Lowest Astronomical Tide), in the office the tidal datum was changed to MSL (mean Sea Level) to tie with the rest of the Bathymetry surveys. 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 as well as geotif formats of 2m 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.