MH370 Phase 1 150m Bathymetry datasets (GA-4421,GA-4422 & GA-4430)

Brief description

On behalf of Australia, the Australian Transport Safety Bureau (ATSB) is leading search operations for missing Malaysian airlines flight MH370 in the Southern Indian Ocean. Geoscience Australia provided advice, expertise and support to the ATSB to facilitate bathymetric surveys, which were undertaken to provide a detailed map of the sea floor topography to aid navigation during the underwater search. Bathymetric data was acquired by multibeam sonar mounted on the hull of multiple vessels (GA survey reference: GA-4421, GA-4422 & GA-4430). Bathymetric surveys were conducted from June 2014 to February 2017, collecting over 710,000 square kilometres of data in the search area and along transit lines (to and from the search area). This dataset allows exploration of the seafloor topography of bathymetry data at a resolution of 150 m across the search and transit areas of the Southern Indian Ocean. The dataset is overlain on a hillshade created from the 150m resolution bathymetry data. The hillshade was created with the parameters of point illumination azimuth at 45 degrees and altitude of 45 degrees.

This dataset is not to be used for navigational purposes.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: The MH370 Search bathymetry Surveys, GA-4421 GP1483 was acquired by the Australian Government through ATSB/GA onboard the MV Fugro Equator from the 05th of June to the 30th of July 2016, GA-4422 through the Chinese Navy Vessel Zhu Kezhen 872 from the 3rd june to 31 August 2014 and from the 5th January to the 30 April 2015 for the MV Fugro Supporter. The bathymetry data were delivered from the Fugro Equator and Fugro Supporter as raw.all files, while the bathymetry acquired by the Zhu Kezhen was delivered as processed ASCII XYZ files. Those three datasets were processed concurrently in Geoscience Australia 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-44S to 50S. 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. Velocity corrections were performed to correct for different artefacts and mismatches. Two grids were produced for each UTM zones, one for the shallow depth (high resolution) and one for the deep depth (lower resolution grid). 9. The processed data was finally exported as grids soundings or false coloured images for presentation and reporting and as final processed data in ASCII XYZ as well as geotif formats of variable resolution. 10-The ASCII grids were then imported into ARC catalogue/info to create a raster file for each UTM zone and one of the entire survey.

Notes

Purpose
Provision , maintenance and dissemination of geoscientific data (bathymetry) to the public. This dataset will give the public a general view of the seabed in the MH370 search area.