The Lord Howe Rise 2D Seismic Survey , GA-0363/KR1715 was acquired by Geoscience Australia onboard the RV Kairei from the 08th of November to the 1st of January 2018.

The Chief scientist onboard was:

Leg1:Dr. Kan Aoike/Dr. Scott Nichol

Leg2:Dr. Kan Aoike/Dr. Scott Nichol

leg3: Dr. Kan Aoike/Dr. Ron Hackney

This dataset was acquired and processed onboard by JAMSTEC and further processing was conducted in the office by Michele Spinoccia, using CARIS HIPS & SIPS ver 7.1.2.

Metadata:

The multibeam bathymetry was acquired by the following survey:

- Survey Name: Lord Howe Rise 2D Seismic Survey (GA-0363/KR1715)

- Vessel Name: RV Kairei

- Institution: Geoscience Australia/ JAMSTEC

- Country: Australia

- Operator: JAMSTEC

- Multibeam system: ELAC Seabeam 3012

- Year of installation: Unknown

- Nominal sonar frequency: 12 kHz

- Number of heads: 1

- Number of beams/head: 301 beams

- Pulse length: variable

- Selectable depth range: 50- 11km (actual depth range recorded 273 to 5100m)

- Vessel speed: 5 - 7 knots

- Start Date: 01/11/2017

- End Date: 01/01/2018

- Start Port: Brisbane

- End Port: Brisbane

- Grid resolution: 70 to 90 m

- Number of grids: 5

- Total surface coverage: 69,190.41 km2

- Vertical Datum: MSL

- Horizontal Datum: WGS84 UTM-56 and 57S

- Use Limitation: This dataset is not to be used for navigational purposes.

- This dataset is published with the permission of the CEO, Geoscience Australia

Processing:

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-56 and 57S.

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.

In GA the tide was applied to the grid to correct for tidal variations and velocity corrections were performed to correct for different artefacts and mismatches.

9. The processed data was finally exported as grids soundings or false coloured images for presentation and reporting and as final processed data in in ASCII XYZ as well as geotif formats at the optimum resolution the data can provide.

10.Using CARIS Base editor 4.1 the grids were exported as ESRI ASCII grid, then imported into ARC catalogue/info to create a raster file for the entire survey as well as Google KMZ.