The Surface Ocean CO2 Atlas (SOCAT) is a synthesis activity by the international marine carbon research community (>100 contributors). SOCAT version 5 has 21.5 million quality-controlled, surface ocean fCO2 (fugacity of carbon dioxide) observations from 1957 to 2017 for the global oceans and coastal seas. Calibrated sensor data are also available. Automation allows annual, public releases. SOCAT data is discoverable, accessible and citable. SOCAT enables quantification of the ocean carbon sink and ocean acidification and evaluation of ocean biogeochemical models. SOCAT, which celebrates its 10th anniversary in 2017, represents a milestone in biogeochemical and climate research and in informing policy.

Supplement to: Bakker, Dorothee C E; O'Brien, Kevin M; Pfeil, Benjamin; Currie, Kim I; Kozyr, Alexander; Landa, Camilla S; Lauvset, Siv K; Metzl, Nicolas; Nakaoka, Shin-Ichiro; Nojiri, Yukihiro; Nonaka, Isao; Olsen, Are; Omar, Abdirahman M; Pierrot, Denis; Saito, Shu; Smith, Karl; Sutton, Adrienne; Sullivan, Kevin; Tilbrook, Bronte; Wanninkhof, Rik; Akl, John; Alin, Simone R; Barbero, Leticia; Barrera, Kira E; Beaumont, Laurence; Becker, Meike; Bernard, Christophe; Bott, Randy; Byrne, Robert; Cai, Wei-Jun; Cosca, Catherine E; Cross, Jessica; Daly, Kendra L; Danguy, Théo; De Carlo, Eric Heinen; Dietrich, Colin; Feely, Richard A; Fiedler, Björn; Glockzin, Michael; Gove, Matthew D; Goyet, Catherine; Guillot, Antoine; Hales, Burke; Hartman, Sue E; Herndon, Julian; Hoppema, Mario; Humphreys, Matthew P; Hunt, Christopher W; Huss, Betty; Hydes, David; Ibánhez, J Severino P; Ishii, Masao; Johannessen, Truls; Jones, Steve D; Kitidis, Vassilis; Knorr, Paul O; Körtzinger, Arne; Kosugi, Naohiro; Lee, Charity M; Lefèvre, Nathalie; Lo Monaco, Claire; Liu, Xuewu; Maenner, Stacy M; Manke, Ansley; Manzello, Derek P; Mathis, Jeremy T; Mickett, John; Millero, Frank J; Monacci, Natalie; Monteiro, Pedro; Morell, Julio; Munro, David R; Musielewicz, Sylvia; Neill, Craig; Newberger, Timothy; Newton, Jan; Noakes, Scott; Noh, Jae Hoon; Ohman, Mark; Ólafsdóttir, Sólveig Rósa; Ólafsson, Jón; Osborne, John; Padín, Xose Antonio; Rehder, Gregor; Reimer, Janet J; Robbins, Lisa L; Rutgersson, Anna; Sabine, Christopher L; Salisbury, Joe; Sasano, Daisuke; Schlitzer, Reiner; Schuster, Ute; Send, Uwe; Sieger, Rainer; Skjelvan, Ingunn; Steinhoff, Tobias; Sutherland, Stewart C; Sweeney, Colm; Takahashi, Taro; Telszewski, Maciej; Vandemark, Douglas C; van Heuven, Steven; Wallace, Douglas WR; Woosley, Ryan J; Wynn, Jonathan G; Yates, Kimberly Kaye (in prep.): Version 5 of the Surface Ocean CO2 Atlas (SOCAT).