Data Types
SADCO stores data from the south-eastern
Atlantic Ocean, the south-western Indian
Ocean and the Southern Ocean, in a
target area extending from
10°N to
70°S and 30°W to
70°E. Data
is obtained from local marine organisations, universities, the South
African
Weather Service, and from international data sources.
The data includes:
- Hydrographic station data with vertical
profiles of temperature, salinity, oxygen, nutrients, etc.
SADCO has about 326 300
stations since 1900.
- Instruments include CTD, MBT, XBT, bottles,
ARGO floats.
- Surface weather reports from
voluntary
observing ships (VOS) including waves, wind, swell, sea-surface
temperature, etc. There
are about 7.3 million reports with
about 64 million observations since 1660.
- Moored current meter and ADCP data
since 1970.
- Moored thermistor string data
since 1990.
- Underway ADCP data since 2000.
- Automatic Weather Station data along the
coast since about 1982.
- Chemical data (in the water column, organic
tissue and in sediment).
- Underwater temperature recording (UTR) data since
1990.
- Wave data from wave buoys since 1977.
Data Quality Control
The quality control procedures for the various types of
data are described in the Newsletters.
- Hydrographic stations: To conform with international checks,
the QC flags of the World Ocean Database (WOD) were adopted, so
that data obtained from the World Data Centre (WDC) could be be
integrated almost seamlessly into the existing SADCO data base.
The QC process involves 3 groups of checks, namely checks of
the station information, checks of the profiles
and checks of the subsurface observations. No flags are
installed for the station checks (stations are either accepted –
sometimes with small corrections - or rejected). For the
profile and observation checks, flags are allocated
per parameter (e.g. temperature, salinity, nutrients,...) and the
flags installed by SADCO are a subset of the WOD flags plus a
spike check. The variables that are checked are: depth, temperature,
salinity, oxygen, phosphate, silicate, nitrate, pH, dissolved inorganic
carbon (DIC) and total chlorophyll. For a more complete description,
please see SADCO newsletter Vol.
18 No. 3 (August 2007)
- VOS: The World Meteorological Organisation quality control
screens are used on SADCO's VOS data. For a complete description,
please see page 4 of
Vol. 13 No. 2 (June 2002) and
Vol. 13 No. 3 (September 2002)
- Time series data: Automatic checking for time series
data are checked visually. Current meter data are checked for
the following: Metadata checks (latitude, longitude, institute,
date, time), broad range check, spikes, noisiness, sensor drift,
visible gaps and/or pre-deployment leaders or post-recovery trailers.
Weather data are checked for the following: Metadata checks (latitude, longitude, institute,
date, time), broad range checks, spikes, sensor drift, data gaps, data shift,
sensor jammed.
For a further description of the criteria, please see SADCO newsletters
Vol. 19 No. 4 (December 2008) and
Vol. 21 No. 1 (February 2010)
AFROBIS
A large amount of
biogeographic data has been loaded in AfrOBIS, the African
Node for the
Ocean Biogeographic Information System. This database as
well as the
global information in OBIS, is freely accessible, and contains search,
plotting
and download facilities (http://afrobis.csir.co.za).
Data Loading
SADCO runs screening tests on all incoming
data to identify possible errors, and attaches quality assessment flags
to the
loaded data. Where
possible, errors are
reported to the contributors for rectification but SADCO has no control
over
the reliability of the submitted data.
Confidential data is placed under access
control allowing access only to those organisations and persons
approved by the
data provider.
SADCO prefers to obtain data in a specified
format, to expedite the loading process.
Target
Area
Map of
target area
Data Being Loaded
List of
data being loaded
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