The Surface Ocean CO₂ Atlas (SOCAT) is a synthesis activity for quality-controlled, surface ocean fCO₂ (fugacity of carbon dioxide) observations by the international marine carbon research community (>100 contributors). SOCAT data is publicly available, discoverable and citable. SOCAT enables quantification of the ocean carbon sink and ocean acidification and evaluation of ocean biogeochemical models. SOCAT represents a milestone in biogeochemical and climate research and in informing policy. SOCAT data are released in versions. Each succeeding version contains new data sets as well as updates of older ones. The first version of SOCAT was released in 2011, the second and third version followed biennially. Automation allowed annual public releases since version 4. The latest SOCAT version (version 5) has 21.5 million observations from 1957 to 2017 for the global oceans and coastal seas. SOCAT contains data from the VOS, OceanSites network and mooring, buoy data in general as well as calibrated sensor data.

VOS/SOOP tracks are usually repeated several times a year and inform about the marine sinks and sources of atmospheric carbon dioxide on a global bases and their variability. Data from this network has been made available to the scientific community and interested public via the Carbon Dioxide Information Analysis Centre (CDIAC) Oceans at the Department of Energy, USA, since the early 1990’s where PIs submitted and shared their data. In 2017, CDIAC Ocean will be named Ocean Carbon Data System (OCADS) and join NOAA’s National Centers for Environmental Information (NCEI). In 2007, the marine biogeochemistry community coordinated by the International Ocean Carbon Coordination Project (IOCCP), launched the Surface Ocean Carbon Dioxide ATlas (SOCAT) in order to uniformly quality control and format the data with detailed documentation. Underway carbon dioxide data from the VOS network are integrated in SOCAT.