Davis Multibeam Survey 2016/17, Antarctica (GA-0357/AAP 5093) - High Resolution Backscatter Grid

Brief description

Geoscience Australia, the Royal Australian Navy (RAN) and the Australian Antarctic Division (AAD) conducted a hydrographic surveying and seafloor characterisation survey in nearshore waters offshore from Davis Station in the Australian Antarctic Territory.

The multibeam data was acquired during January-February 2017 using two workboats. Geoscience Australia used the AAD workboat Howard Burton and the Royal Australian Navy used their Antarctic Survey Vessel (ASV) Wyatt Earp. The survey is a component of Australian Antarctic Program (AAP) Project 5093 Hydrographic Surveying and Seafloor Characterisation Program (Chief Investigator: Ursula Harris, AAD).

The objective of the survey was to map the seabed environment in shallow (<300 m) coastal waters adjacent to Davis station in the Vestfold Hills region, to obtain data for the compilation of nautical charts and to acquire fundamental baseline data necessary for informed environmental management, science, infrastructure and logistical operations.

Data collected during the survey includes high-resolution multibeam bathymetry and backscatter data, sediment samples, seafloor imagery and sub-bottom profiles.

This dataset comprises a backscatter grid from multibeam sonar data acquired using the AAD workboat Howard Burton, gridded at 2 m spatial resolution, covering a combined area of 90 km2. The Chief Scientist onboard the Howard Burton was Dr. Jodie Smith (Geoscience Australia).

Lineage

Maintenance and Update Frequency: asNeeded

Statement: This dataset was acquired using Kongsberg's SIS acquisition software and pre-processed onboard using CMST-GA MB Process v15.04.04.0 software by Kim Picard.

Processing:
1. Multibeam data were collected using a Kongsberg EM2040C multibeam echosounder system, mounted in the moon pool of the Workboat Howard Burton. Motion referencing and navigation data were collected with an Applanix Position and Orientation system and a C-Nav GPS system, respectively. Multibeam data were acquired using Kongsberg’s Seabed Information System (SIS) software.
2. These data were processed using the multibeam backscatter CMST-GA MB Process v15.04.04.0 (x64) toolbox software co-developed by the Centre for Marine Science and Technology (CMST) at Curtin University of Technology and GA (described in Gavrilov et al., 2005; Parnum and Gavrilov 2011).
3. The process involved removal of the system transmission loss, removal of the system model, calculation of the incidence angle, correction of the beam pattern, calculation of the angular backscatter response within a sliding window of 100 pings with a 50% overlap in a 1° bin, removal of the angular dependence, and restoration to the backscatter strength at an angle of 25°. The final processed backscatter data were then gridded to 2 m horizontal resolution and exported for display and analysis.
In GA, further process was conducted by Justy Siwabessy to fine tune beam pattern correction.
4. The processed data was finally exported as a grid in the optimum resolution the data can provide.

Metadata:
The multibeam bathymetry was acquired by the following survey:
- Survey Name: Davis Station Marine Survey 2016 (GA-0357)
- Vessel Name: AAD Workboat Howard Burton
- Institutions: GA, RAN, AAD
- Country: Australia
- Operator: AAD
- Multibeam system: Kongsberg EM2040C
- Year of installation: 2014
- Nominal sonar frequency: 300 kHz
- Number of beams: 400 beams
- Beamwidth across track: 1.3°
- Beamwidth along track: 1.3°
- Pulse length: variable
- Selectable depth range: 0.5m - 450m
- Vessel speed: 6 - 8 knots
- Start Date: 10/01/2017
- End Date: 06/02/2017
- Start Port: Davis Station
- End Port: Davis Station
- Processing software: CMST-GA MB Process v15.04.04.0
- Grid resolution: 2m
- Number of grids: 1
- Total surface coverage: 90 km2
- Horizontal Datum: WGS84 UTM-43S

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