SOCAT (Surface Ocean CO2 Atlas) represents an effort to "provide a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC)." The data sets are comprised of observations (ship track) and gridded data.
National Center for Atmospheric Research Staff (Eds). Last modified 21 Aug 2014. "The Climate Data Guide: SOCAT: Surface Ocean CO2 Atlas ." Retrieved from https://climatedataguide.ucar.edu/climate-data/socat-surface-ocean-co2-atlas.