Darwin Harbour Bathymetry Survey 2010 (GA0333)

Brief description

The Darwin Harbour bathymetry survey, GA-0333 was acquired by Geoscience Australia (GA), iXSurvey Australia Pty Ltd, and the Darwin Port Corporation (DPC) onboard the vessel 'Matthew Flinders' from 17 October to 07 November 2010 using GA's Kongsberg EM3002D multibeam sonar system and DPC's The specific objectives of the survey were to: 1. Obtain high resolution geophysical (bathymetry) data for Darwin Harbour; 2. Characterise substrates (acoustic backscatter properties, grainsize, sediment chemistry) for Darwin Harbour; and 3. Collect tidal data for the survey area. This V0 dataset contains a 1m resolution 32-bit geotiff of the Darwin Harbour survey area produced from the processed EM3002D sonar bathymetry data. This dataset is published with the permission of the CEO, Geoscience Australia Not to be used for navigational purposes.

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. The Chief Scientist onboard was Dr Neil Smit. This dataset was produced using CARIS HIPS/SIPS v.7.1.2 The vertical datum is MSL while the horizontal datum is WGS84 UTM-52S. For any metadata questions, please download the Metadata.txt file located with the dataset. Processing methodology: Following the CARIS HIPS/SIPS workflow, 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 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 a 32 bit Geotif format at 1m resolution. =