Data processing at national centres is divided in different steps as given below and that will be described in the following paragraphs. Broadly it is divided in 3 steps viz. Data ingestion, Real time Quality control and Data transmission on GTS and to Global argo centres
Data are transmitted from floats while they are on the surface. The satellite communications system (e.g. Service ARGOS, others) relays the data to ground stations. These either send the data to the processing Centres, or processing Centres connect directly to the communications system provider to download data. This data transfer happens several times a day. Many of the countries supplying floats also have a national centre designated to process the data. Although the exact nature of the work carried out at these Centres varies, each is generally responsible for converting the data stream from each float to profile and drift information. They also have the responsibility to maintain the master versions of metadata concerning the float specifications.
Data tracking is needed to assure that all National Centres and designated users are receiving the appropriate data and at the appropriate schedules. The first step in data tracking is registration of new float information by PIs. The PI registers newly deployed floats by forwarding necessary information to the appropriate National Centre. This information is relayed to the Global ARGO Centres. Such information allows the National Centre to anticipate the arrival of profiles and to initiate inquiries when data are not received. Each National Centre holds the master list of instruments, profiles and current float status for the region, or PIs for which they are responsible.
Real time Quality control
National centres prepare the data for dissemination on the GTS using basic set of QC tests ([QC]). They also relay data to National Science team within their country or who use the services of the processing centre. At the same time, within 24 hours, the information from the float is also sent to the Global ARGO Centres as an alternate dissemination channel to the GTS for research and modellers community. In some cases, the national processing centre may also act as a distribution centre within their own country for all ARGO data collected in a region of interest to national Science team.
Data transmission on GTS and to Global argo centres
National Centres relay the data to the appropriate Investigator for delayed mode qualification. Upon receiving data from the Investigators, the National Centre has the responsibility to ensure that the content of the return file is good as well as the fact that each Investigator made an appropriate entry (entries) in the History section of the Netcdf file. If this information is missing, the centre is responsible for working with the Investigator to ensure proper information is included before the data are sent on to the Global ARGO Centres. This transfer of delayed mode profiles should occur within 5 months of the observation date of the profiles. Additionally, if analysts at Regional Centres raise questions about the data, if corrections are made by a Investigators, these pass through the National Centres back to the Global ARGO Centres.