Bathymetry grid of the Lord Howe survey area

Note: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2.

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Dataset citation

ANZLIC unique identifier: ANZCW0703015215

Title: Bathymetry grid of the Lord Howe survey area

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Custodian

Custodian: Geoscience Australia

Jurisdiction: Australia

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Geoscience Australia carried out a marine survey on Lord Howe Island shelf (NSW) in 2008 (SS062008) to map seabed bathymetry and characterise benthic environments through colocated sampling of surface sediments and infauna, rock coring, observation of benthic habitats using underwater towed video, and measurement of ocean tides and wavegenerated currents. Subbottom profile data was also collected to map sediment thickness and shelf stratigraphy. Data and samples were acquired using the National Facility Research Vessel Southern Surveyor. Bathymetric data from this survey was merged with other preexisting bathymetric data (including LADS) to generate a grid covering 1034 sq km. As part of a separate Geoscience Australia survey in 2007 (TAN0713), an oceanographic mooring was deployed on the northern edge of Lord Howe Island shelf. The mooring was recovered during the 2008 survey following a 6 month deployment. lh_4m is an ArcInfo grid of the Lord Howe survey area produced from the processed EM300 bathymetry data of the survey area using the CARIS HIPS and SIPS software.

ANZLIC search words:

GEOSCIENCES Mapping
MARINE

Spatial domain:

locality map

Geographic extent name: AUSTRALIA EXCLUDING EXTERNAL TERRITORIES - AUS - Australia - Australia

Geographic extent polygon: 158.8 -31.3, 159.4 -31.3, 159.4 -31.9, 158.8 -31.9, 158.8 -31.3,

Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register

Geographic bounding box:: North bounding latitude: -31.3 °; South bounding latitude: -31.9 °; East bounding longitude: 159.4 °; West bounding longitude: 158.8 °

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Data currency

Beginning date: 2010-12-20

Ending date: 2010-12-20

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Dataset status

Progress: Complete

Maintenance and update frequency: Not Known

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Access

Stored data format:: DIGITAL - ArcGIS-grid ArcInfo grid

Available format type:: DIGITAL - ArcGIS-grid ArcInfo grid

Access constraints:

This material is released under the Creative Commons Attribution 3.0 Australia Licence.

The bathymetry grids are not to be used for any navigational puprposes.

Free Data Download

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Data quality

Lineage:

Due to the good quality data being acquired, post processing of the raw data was kept to a minimum. Swath data was processed through Caris HIPS/SIPS version 7.2. First a vessel configuration file was created that the coordinates of the motion sensor and DGPS antenna and patch test offsets were recorded. A new project was then created and the vessel configuration file was attached to the project file. 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. The motion sensor, DGPS and heading data were then cleaned using a filter that averaged adjacent data to remove artifacts. 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. Then a new blank field area was defined that specified the geographic area of study and the coordinate system used. The coordinates for all the study areas were WGS84. 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. In addition, WXTide32 software (http://www.wxtide32.com) with reference to the mean sea level and UTC time was used to obtain tidal information, which in turn was used to correct for the tidal variations in the processing. 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. The processed data was finally exported as XYZ grid soundings and converted into ArcINFO grid.

Positional accuracy:

The positional accuracy is high as required by the multibeam sonar system to properly function

Attribute accuracy:

The accuracy is high but it is cell size dependent. Note that the water depth dictates the cell size

Logical Consistency:

All procedures, steps and software involved in producing a bathymetry grid are similar

Completeness:

Completed

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