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 the 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 Brest, France and 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.

Given the expanding size of the Argo data system, there are other ways to access Argo data besides downloading the netCDF files from the GDACs. There are gridded fields and velocity products available as well as data viewers developed to look at the Argo dataset. To look at individual float data, use the individual float description tool at Coriolis. To select a group of floats within a certain region or time, use one of the data selection tools to the right. See the links to the right for all the options. There is also a beginner's guide to Argo data.

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

The 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.