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, which celebrated its 10th anniversary in 2017, 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 2022) has 35.6 million observations from 1957 to 2022 for the global oceans and coastal seas. 7.2 million calibrated sensor observations are also available.

SOCAT version 2023 was released on the 20th of June 2023, containing data submitted on or before 15th of January 2023. New data submissions are welcome at any time, and will be included in the next SOCAT release. The submission deadline for v2024 is 15 January 2024.

SOCAT is a core Global Ocean Observing System data product for biogeochemistry endorsed by the Global Ocean Observing System GOOS.