1. Australian Antarctic Data Centre
2. Discover and Manage Data
3. Records
4. BROKE-West_hydroacoustic_dataset

Description

This dataset contains data files, processing templates and documentation relating to the BROKE-West multifrequency echosounder (acoustic) survey carried out from the RSV Aurora Australis in the austral summer of 2005/06 (ASAC project 2655). The primary aim of the acoustic survey was to describe the distribution and abundance of Antarctic krill (Euphausia superba) in CCAMLR Division 58.4.2. However, these data are also relevant for studies of other sound-scattering targets detected by the echosounder system, for example other pelagic taxa or the seafloor.

The dataset is a collection of *.csv data files, *.ev processing files and *.pdf documentation files, organised into 4 categories:

1. Acoustic survey: data files relating to the transects undertaken for the acoustic survey 2. Acoustic data processing: metadata files, processing templates and documentation relating to the collection and processing of the acoustic data 3. Acoustic results: results arising from the processing of the raw data. The raw data are described in a separate metadata record - "AAD Hydroacoustics hard disks - data collected from Southern Ocean cruises..." 4. Ancillary data: additional non-acoustic data used during the processing of the acoustic data

The file "data_fields.pdf" lists and describes the fields in each of the *.csv data files.

The file "processing_methods.pdf" provides a synopsis of the methods by which the raw acoustic data were collected and processed.

The BROKE-West survey was conducted on voyage 3 of the Aurora Australis during the 2005-3006 season. It was intended to be a comprehensive biological and oceanographic survey of the region between 30 degrees and 80 degrees east.

Quality

There are two minor issues regarding the EDSU-level NASC and rho data representing krill:

1. The files "edsu-2000-250-250_120H_nasc-rho_krill_meth1.csv" and "edsu-2000-250-250_120H_nasc-rho_krill_meth2.csv" do not contain valid seafloor depth values due to an oversight when exporting the original bin-level data from Echoview. It would be possible to rectify this if there were sufficient cause, although it would be a lengthy process. It would be sufficient to use the seafloor data from the file "edsu-2000-250-006_120H_nasc-rho_krill_meth3.csv" instead, but note issue 2 below.

2. The definitions for a number of EDSUs along Transect 2 in the file "edsu-2000-250-006_120H_nasc-rho_krill_meth3.csv" are mismatched by 1-2 minutes from those in the files "edsu-2000-250-250_120H_nasc-rho_krill_meth1.csv" and "edsu-2000-250-250_120H_nasc-rho_krill_meth2.csv", resulting in the delineation of 1 additional EDSU. This affects the data between 25-Jan-2006 15:31 (UTC) and 26-Jan-2006 16:22 (UTC). The cause of this is unclear at present, but is likely to relate to the implementation of positional information within Echoview and minor variation arising from the export of different varaiables from Echoview. Given the short offset, the significant of this difference appears to be negligible.

Access

These data are publicly available for access, but are too large to be downloaded. They are available on request to the Australian Antarctic Data Centre.

Temporal Coverages

• Start date: 2006-02-02 - Stop date: 2006-03-12

Spatial Coverages

Science Keywords

• EARTH SCIENCE > BIOSPHERE > ECOLOGICAL DYNAMICS
• EARTH SCIENCE > OCEANS > OCEAN ACOUSTICS
• EARTH SCIENCE > BIOSPHERE > ECOSYSTEMS > AQUATIC ECOSYSTEMS > PLANKTON
• EARTH SCIENCE > BIOSPHERE > ECOSYSTEMS > AQUATIC ECOSYSTEMS

Use Constraints

This data set conforms to the CCBY Attribution License (http://creativecommons.org/licenses/by/4.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=BROKE-West_hydroacoustic_dataset when using these data.