The Argo Data System
When a float surfaces, the data are transmitted
and the float's position is determined either by
Système Argos or by GPS. The Système Argos data are monitored by
Argo Information Centre (AIC) in France and then received by national data
centers (DACs). The data from floats using other communications systems may go directly
to the float's owner or to the AIC before arriving at the DACs.
At the DACs, they are subjected to initial scrutiny using an agreed upon set of
real time quality control tests (see the
ADMT Documentation page for a description of the tests) where
erroneous data are flagged and/or corrected and
the data are passed to Argo's two Global Data
Assembly Centers (GDACS) in
Monterey, California. The GDACs are the first stage
at which the freely available data can be obtained via the internet. The
GDACs synchronize their data holdings to ensure consistent data is available
on both sites.
The data reach
operational ocean and climate forecast/analysis
centers via the
Global Telecommunications System (GTS).
The target is for these "real-time" data to be
available within approximately 24 hours of their
transmission from the float.
Real time data flow
In addition to the real-time data stream, Argo
has the potential, after careful data
assessment, to provide
salinity/temperature/pressure profiles that
approach ship-based data accuracy.
In general there is no possibility of carrying
out calibration checks on a float's sensors
after it has left the laboratory or has been
launched by a research ship that might make a
nearby CTD cast. One means of adjusting
salinities is to look at deviations of the float
data from a stable, deep temperature/salinity
climatology [Owens et al., 2009, Bohme et al., 2005, Wong et al., 2003], or to compare
profiles from floats that coincide in space and
time. The OW method (Owens et al., 2009) has been adopted by
Argo as its standard means of delayed mode data
quality control. The delayed-mode quality
control is the responsibility of researchers in
each country in collaboration with the
appropriate national data center. It has been
recommended that delayed mode data inspection is
carried out on a 1 year long record so that
sudden jumps in calibration may be distinguished
from long term drift or water mass property
changes. This imposes a minimum 6 month delay on
the availability of delayed mode data.
This system was adopted in 2004 and is now being
applied to Argo data. These delayed-mode data
are currently available from the GDACs. To learn more about the data management of Argo and
how to use the Argo data effectively, visit the
Argo Data Management Website.
An additional phase of Argo data management occurs at a regional level at the Argo Regional Centers (ARCs). This enables
the accumulation of consistent regional data
sets and the production of Argo based products.
To learn more about the Argo Regional Centers, go to ARC page.
Real time and delayed mode data flow
Argo Information Centre is a source of
information about the development and performance
of the global array and the national programmes
that contribute to it.
The final repository for Argo data is with the
US National Oceanographic Data Center ( NODC ).
They will also distribute Argo data on CDs so as
to permit Argo data use by groups without
reliable or low cost internet access.