Anthropogenic carbon estimation in the surface ocean from atmospheric CO2 fugacity at the BATS (Bermuda Atlantic Time-series Study) station

In surface seawater, it is usually very difficult to quantify anthropogenic carbon concentrations. Many processes (such as air-sea exchanges of gases and heat, biological activity, and mixing of water masses), are at play and often on different timescales. Thus, various hypotheses are used to estimate the anthropogenic concentrations in surface waters. Here, using the relatively long (1980s to present) time series data sets from the Bermuda Atlantic Time-series Study site (BATS; 31 degrees 40 ' N, 64 degrees 10 ' W) in the North Atlantic Ocean, we evaluate results based upon two different hypotheses. The results clearly confirm that it is very difficult to assess anthropogenic carbon con-centrations in surface waters from sole oceanic properties. However, this study further indicates that at this ocean site, they can be appropriately determined from low-frequency variations of atmospheric CO2 concen-trations. Consequently, the impact of anthropogenic carbon penetration in surface waters on their acidification could be predicted.