Sections below: Overview | BOA versions | Access | Reference | Variables | CMAR staff

BOA - a quality controlled collation of the world's hydrographic data


What is BOA?

BLUElink Ocean Archive (BOA) is the result of collecting together the majority of global high-quality buoy and shipboard deepwater hydrographic cast data. It is built on the NOAA/NODC World Ocean Database, WOCE WHP3, Argo, TAO, CSIRO and NIWA archives, and a number of other sources. BOA is an integral component of the development of the CARS climatologies.

The quality control of profile data involves many steps, including:

  • location and depth plausibility check
  • value range checking against 3D global value range tables
  • comparison to global S(T) climatology for outlier detection
  • comparison to existing CARS seasonal estimates (ie residuals testing) for outlier detection
  • ingestion into CARS, and a second level of residuals testing, using a tighter threshold (thresholds are set as a multiple of the mapped RMS of residuals.)
  • examination of resultant CARS fields, especially for bullseyes and structure in the RMS-residuals and seasonal harmonics fields, since these are more sensitive to bad data.

Prior to being compared with CARS fields, the profiles are interpolated onto a set of 79 CSIRO Version-3 Standard Depth Levels (CSL3).

The component datasets of BOA are stored separately in a range of formats since the nature of these datasets is quite varied. This approach allows easy updating of components (for example, the Argo subset is completely renewed every couple of months.) Where the same data could reside in multiple datasets, those datasets are duplicate cross-checked after any updates (scanning only on the basis of time and location, not the enormous task of searching for duplicated property profiles.)

Data sources

The component datasets of BOA include:
Major input datasets URL
World Ocean Database NODC home page
WOCE WHP3.0 WOCE Data resource page
CSIRO data holdings CMAR home page
Argo floats Argo home page
TAO array TAO home page


BOA Versions

2009

BOA09 is now a global dataset, and is the basis for CARS2009. Only the temperature and salinity data in BOA09 has received the full QC treatment since CARS2009 presently only consists of those two properties. Also BOA09 is not yet packaged into netCDF files for download. It is based on the July 2008 update of World Ocean Database 2005, and pressure-corrected Argo data (to March 2009) forms a huge part of it.

2006

BOA06 is still the principal version of BOA because it is available for all 6 water properties, and is packaged into netCDF files for download. It is based on World Ocean Database 2001. This dataset is limited to around 30N (only 10N in the Atlantic). Because TAO is a very large and different type of dataset, it is stored in separate files.

Fully quality-controlled properties
Versionproperties
2009temperature salinity
2006temperature salinity oxygen nitrate silicate phosphate


Accessing BOA

If publications arise from work that makes use of BOA, please send us a copy, via email
Jeff.Dunn@csiro.au
or to:
Jeff Dunn
CSIRO Marine Laboratories
GPO Box 1538
Hobart, TAS, 7000, Australia

BOA06 is available in a packaged form of one netCDF file per property (created in July 2006.) Neutral density profiles are also computed and stored in file gamma_BOA06.nc.These files are all available:

  • via this OpenDAP (DODS) link
  • from pub/omas/BOA/ at ftp.marine.csiro.au


    Variables

    QC flags are not provided in the packaged BOA files. All suspect data has been removed - all remaining values are presumed good.

    Principal data variables
    Namedescriptionunits
    stnnoStation number - unique within component dataset
    dsetCode identifying component dataset: eg 19=WOCE, 21=WOD2001 CTD
    lat,lonlatitude,longitudedecimal degrees
    0-360E,-ve=S
    timedate/time of profile etcdecimal days since 1/1/1900
    zdepthmetres
    ttemperature (not converted from originator ITS)deg C
    ssalinityPSU
    o2oxygenml/litre
    sisilicatemicromole/litre
    po4phosphatemicromole/litre
    no3nitratemicromole/litre


    References

    Ridgway K.R., J.R. Dunn, and J.L. Wilkin, Ocean interpolation by four-dimensional least squares -Application to the waters around Australia, J. Atmos. Ocean. Tech., Vol 19, No 9, 1357-1375, 2002


    CSIRO staff only:

    Within the CSIRO Marine Laboratories computer network, BOA09 can be accessed using Matlab function get_all_csl3 in /home/eez_data/software/matlab. The original observed-level form of many of the datasets can also be accessed using get_all_obs. Other routines are available (see CARS/BOA Utilities.)

    Observed level data is stored with the same depths applying to all property measurements for a given profile, except for TAO. The z dimension for all data returned via get_all_obs is Depth, never Pressure.

    Additional data variables
    Namedescriptionunits
    castflagnumeric whole-profile QC flag. May contain originator QC in units digit, and CSIRO QC in 2nd and 3rd digits
    qcflagnumeric per-obs QC flag. May contain originator QC in units digit, and CSIRO QC in 2nd digit

    The packaged version of BOA06 is stored in /home/eez_data/BOA/.

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