Controls on fCO2 in the South Pacific

One aspect of the JGOFS/WOCE programs is the generation of a global CO2 data set which will be significantly better in sampling density and quality than existed before. This data will be extremely valuable to geochemists and modelers interested in the global carbon cycle. Nevertheless, it will still be necessary to interpolate measurements both temporally and spatially to incorporate the results into global circulation models. This paper presents a new method that attempts to quantify the processes known to influence surface ocean CO2 fugacity. The method is tested using data collected along a Pacific WOCE section (P17E) across the Southern Ocean. These calculations offer more insight into the factors controlling fCO2 than published analysis/interpolation schemes in that individual effects are quantified without resorting to empirical relationships. The procedure works extremely well for spatial interpolation along section P17E and sheds insight into physical processes (mixing and air–sea gas exchange) where model results differ from observations. If the method proves to be robust when applied to other areas, it will be a significant step toward interpolation of sparse ocean CO2 measurements in order to calculate either regional or global CO2 fluxes.