ACS data collected on the BROKE-West voyage of the Aurora Australis, 2006
Profiles of visible light absorption and attenuation coefficients were measured in the upper 100m of the water column.
Data Acquisition:
The Wetlabs ACS spectral absorption and attenuation meter was mounted on a deployment frame together with a Seabird pump, a Wetlabs DH-4 data logger and two battery packs. This set-up was as recommended in the Wetlabs manual. The logger was set to control the ACS once the on/off magnet had been inserted. The data acquisition program comprised 2 minutes delay time to allow the instrument to be deployed over the stern; 30 seconds warm-up time; 30 seconds flush time during which the pump was activated, and finally 12 minutes of data acquisition. Physically, the instrument was attached to the winch, the magnet was inserted as soon as permission to deploy had been obtained from the bridge, the instrument was lowered directly to 20m, until 1.5 minutes since insertion of the magnet. The instrument was then brought to just below the surface and lowered at 0.5m per second to a depth of 100m, then retrieved at the same speed. Once the instrument was back on deck the magnet was removed to prevent dry operation of the pump.
The data logger received an instrument-specific binary format data file for each deployment, with automatic sequential file numbering. These files were uploaded after each deployment.
Data Processing:
The Wetlabs software program WAP was used to extract ascii data from the binary files. This procedure included corrections for internal instrument temperature and the latest manufacturer's calibration for wavelength. Note that although daily calibrations were performed during the cruise, the manufacturer advised against using these calibrations as conditions were suboptimal (milli-Q water not fresh, environment not totally dry or well temperature-controlled).
A matlab script, acs.m, written by the principal investigator, continues the data processing. Data recorded in air are discarded, remaining data are binned to 2m depth intervals, occasional spurious data with a discontinuity in absorption or attenuation spectra are removed, and a correction is applied to account for differences in ocean water temperature and salinity compared to the calibration conditions. This final step uses first-cut CTD data courtesy of the oceanography team (Bindoff et al).
Not yet complete (as of 2006-03-10):
Remaining spurious data need to be weeded out by hand. These include non-systematic quirks such as occurrence of bubbles or larger particles in the optical path.
The depth needs to be corrected for an offset of some 4m plus the difference between the pressure sensor location and the ACS-inlet location.
Dataset Format:
For each 100m profile, a single ascii file is available, comprising instrument calibration data and a time sequence of attenuation and absorption spectra. By placing each of the profile files from one cruise transect in a single directory, the acs.m routine can be applied to one leg at a time, yielding matlab fields of [station, depth (0:2m:100m), wavelength (87 wavelengths)]. The acs.m script includes details of which CTD station number refers to which ACS file number. This information is also supplied in the station log file jill_brokew_stations.xls.
Acronyms Used:
ACS - Absorption (a) Attenuation (c) Spectral meter, produced by Wetlabs
CTD - Conductivity, Temperature, Pressure.
This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).
Simple
Identification info
- Alternate title
- ACS data collected on the BROKE-West voyage of the Aurora Australis, 2006
- Date (Publication)
- 2010-08-19
- Edition
- 1
- Citation identifier
-
Dataset DOI
- Title
- Information and documentation - Digital object identifier system
- Date (Publication)
- 2012-04-23
- Citation identifier
- ISO 26324:2012
- Citation identifier
- doi:10.4225/15/5983f15b3fbde
Originator
Publisher
Principal investigator
Collaborator
- Name
- CAASM Metadata
- Status
- Completed
Custodian
- Topic category
-
- Oceans
Extent
Extent
- Description
- Temporal Coverage
Temporal extent
- TimePeriod
- 2006-01-17 2006-02-28
Extent
- Description
- Vertical Extent - Depth
Vertical element
- Minimum value
- 0
- Maximum value
- 100
- Identifier
- urn:x-ogc:def:cs:EPSG:6498
- Name
- Vertical CS. Axis: depth (D). Orientation: down. UoM: m.
- Identifier
- urn:x-ogc:def:axis:EPSG:113
- Name
- depth
- NASA/GCMD Earth Science Keywords
-
- EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > WATER CHARACTERISTICS > LIGHT TRANSMISSION
- EARTH SCIENCE > OCEANS > OCEAN OPTICS > ABSORPTION
- EARTH SCIENCE > OCEANS > OCEAN OPTICS > ATTENUATION/TRANSMISSION
- Keywords
-
- ABSORPTION
- ATTENUATION
- SCATTERING
- HIGH SPECTRAL RESOLUTION
- ACS
- Spectral Attenuation and Absorption Meter
- NASA/GCMD Earth Science Keywords
-
- SPECTROMETERS
- NASA/GCMD Earth Science Keywords
-
- SHIPS
- R/V AA > R/V Aurora Australis
- NASA/GCMD Earth Science Keywords
-
- AMD/AU
- CEOS
- AMD
- ACE/CRC
- NASA/GCMD Earth Science Keywords
-
- OCEAN > SOUTHERN OCEAN
- CONTINENT > ANTARCTICA
- GEOGRAPHIC REGION > POLAR
Resource constraints
- Use limitation
- This metadata record is publicly available.
Resource constraints
- Access constraints
- licence
- Other constraints
- These data are publicly available for download from the provided URL, and are supplied together with matlab scripts for processing and viewing the data.
Resource constraints
- File type
- Portable Network Graphic
- Title
- Attribution 4.0 International (CC BY 4.0)
- Website
-
https://creativecommons.org/licenses/by/4.0/legalcode
Legal code for Creative Commons by Attribution 4.0 International license
- Use constraints
- licence
- Other 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=AAS_4292_MICRE when using these data.
- Language
- English
- Character encoding
- UTF8
Distribution Information
Distributor
Distributor
Distributor
- Fees
- free
- Planned available datetime
- 2010-08-19T00:00:00
- Units of distribution
- MB
- Transfer size
- 353
- OnLine resource
-
GET DATA
Download point for the data
- OnLine resource
-
PROJECT HOME PAGE
Public information for ASAC project 2655
- OnLine resource
-
PROJECT HOME PAGE
Public information for ASAC project 2679
- OnLine resource
-
VIEW RELATED INFORMATION
Home page for Wetlabs - designer of the ACS instrument
- OnLine resource
-
VIEW RELATED INFORMATION
Citation reference for this metadata record and dataset
Resource lineage
- Statement
- Data quality appear good throughout. The ACS was successfully deployed at all CTD stations from CTD-22 to CTD-118, except CTD-59. See the parent record for details on the locations of these stations.
- Hierarchy level
- Dataset
- Maintenance and update frequency
- As needed
- Maintenance note
- 2008-02-08 - record updated by Dave Connell - Distribution field updated. 2010-08-19 - record updated by Dave Connell to publicly release the data. 2017-08-04 - record updated by Dave Connell - basic updates. 2019-03-15 - record updated by Dave Connell for ISO compliance.
Metadata
- Metadata identifier
- string/BROKE-West_ACS
- Language
- English
- Character encoding
- UTF8
Author
Sponsor
Owner
- Title
- Parent Metadata Record
- Citation identifier
- BROKE-West
Type of resource
- Resource scope
- Dataset
Alternative metadata reference
- Title
- gov.nasa.gsfc.gcmd
- Citation identifier
- 99132836-4c5b-4c94-acc8-3178bc46f46d
Alternative metadata reference
- Title
- gov.nasa.gsfc.gcmd
- Date (Last Revision)
- 2019-03-15T15:01:50
Identifier
- Description
- metadata.extraction_date
Alternative metadata reference
- Title
- gov.nasa.gsfc.gcmd
- Citation identifier
- 8.6
- Metadata linkage
-
http://data.aad.gov.au/metadata/records/BROKE-West_ACS
Point of truth for the metadata record
- Date info (Creation)
- 2006-03-10T00:00:00
- Date info (Last Update)
- 2019-03-15
Metadata standard
- Title
- ISO 19115-3
- Edition
- 2014
- Other citation details
- Version 1
- Title
- DIF to ISO 19115-1 Profile