We have developed a statistical gap-ﬁlling method adapted to the speciﬁc coverage and prop-erties of observed fugacity of surface ocean CO2(fCO2). We have used this method to interpolate the Sur-face Ocean CO2Atlas (SOCAT) v2 database on a 2.5832.58 global grid (south of 708N) for 1985–2011 atmonthly resolution. The method combines a spatial interpolation based on a ‘‘radius of inﬂuence’’ to deter-mine nearby similar fCO2values with temporal harmonic and cubic spline curve-ﬁtting, and also ﬁts long-term trends and seasonal cycles. Interannual variability is established using deviations of observations fromthe ﬁtted trends and seasonal cycles. An uncertainty is computed for all interpolated values based on thespatial and temporal range of the interpolation. Tests of the method using model data show that it performsas well as or better than previous regional interpolation methods, but in addition it provides a near-globaland interannual coverage.