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.


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