Results

The results of this work are monthly global fields of TCO₂ and TALK, the coefficients used to compute these CO₂ system properties, and the maximum mixed layer depths used to define the shallowest depth for these computations. Figure 1 shows the geographical distribution of the maximum depth of the mixed layer. The deepest mixed layers are observed in the northern Atlantic Ocean. The Southern Ocean south of 50° S is a large area with deep mixed layers as a result of the strong atmospheric forcing. The shallowest (< 20 m) mixed layers are observed at low latitudes.

Figure 2 and Figure 3 illustrate the annual mean concentrations of TCO₂ and TALK, respectively, at 500 m, 1500 m, and 3500 m between 60° N and 60° S. These maps clearly show the differences between the three major oceans. In the Pacific Ocean, TCO₂ concentrations are generally higher on the eastern side than on the western side. At 500 m, TCO₂ concentrations have the signature of the upper layers and reflect the circulation patterns. The equatorial upwelling is particularly evident with TCO₂ concentrations higher on the eastern side than the western side.

At 1500 m, the highest concentrations are observed in the Pacific Ocean north of 35° N, while the lowest concentrations are observed in the Atlantic Ocean north of 35° N. At 3500 m, TCO₂ concentrations in the Indian Ocean are comparable to those in the Pacific Ocean at similar latitudes. The lowest TCO₂ concentrations are observed in the northwestern Atlantic Ocean. At 3500 m, TCO₂ concentrations typically differ by 200 µmol/kg or more between the different ocean basins of the Northern Hemisphere. In contrast, in the Southern Hemisphere south of 40° S, the variation of TCO₂ concentration between oceans is typically less than 50 µmol/kg.

At 500 m, TALK is lowest in the Pacific Ocean. However, at 1500 and 3500 m, TALK is lowest in the Atlantic Ocean. In contrast to TCO₂, the highest TALK concentrations are in the northern Indian Ocean.