Surface ocean fCO2 observations taken by a General Oceanics system on Research Vessel G O Sars during 2023, plus older data not previously submitted. Data includes fCO2 plus other variables required for its calculation using methods from Pierrot et al. 2009 (doi: 10.1016/j.dsr2.2008.12.005). Quality control flags indicate Good (2), Questionable (3) or Bad (4) data for each value. Type columns indicate Measured (M), Interpolated (I) or Nominal (N) values.