text: The synergy between the atmospheric concentration measurements, the knowledge of local ecosystem fluxes on the other hand, has shown effective in reducing the uncertainties on carbon assessments. However, in Europe, observatories are all managed differently for each country and data is not homogeneously processed.
  The value added impact of the infrastructure allows an enhanced visibility and dissemination of European greenhouse gas data and products that are both long-term and carefully calibrated. ICOS meets the data needs of carbon cycle and climate researchers as well as those of politicians and the general public. ICOS serves as the backbone to users engaged in developing data assimilation models of greenhouse gas sources and sinks, namely reverse modelling, which allows the deduction of surface carbon flux pattern.
  A common data centre, the ICOS Carbon Portal, provides free access to all ICOS data, as well as to links with inventory data, and outreach material. This portal allows the production of web based tools for the survey of sources and sinks in near real-time. ICOS delivers the information in near real-time with a quantification of the uncertainty associated with the results due to the use of several different models using different methodologies.
  ICOS enables Europe to be a key global player for in-situ observations of greenhouse gases, data processing and user-friendly access to data products for validation of remote sensing products, scientific assessments, modelling and data assimilation.