On the penetration of anthropogenic CO2 into the North Atlantic Ocean

The penetration of anthropogenic or "excess" CO2 into the North Atlantic Ocean was studied along WOCE-WHP section A2 from 49 degrees N/11 degrees W to 43 degrees N/49 degrees W using hydrographic data obtained during the METEOR cruise 30-2 in October/November 1994. A backcalculation technique based on measurements of temperature, salinity, oxygen, alkalinity, and total dissolved inorganic carbon was applied to identify the excess CO2. Everywhere along the transect surface water contained almost its full component of anthropogenic CO2 (similar to 62 mu mol kg(-1)). Furthermore, anthropogenic CO2 has penetrated through the entire water column in the western basin of the North Atlantic Ocean. Even in the deepest waters (5000 m) of the western basin a mean value of 10.4 mu mol kg(-1) excess CO2 was calculated. The maximum penetration depth of excess CO2 in the eastern basin of the North Atlantic Ocean was similar to 3500 m with values falling below 5 mu mol kg(-1) in greater depths. These results compare well with distributions of carbontetrachloride. They are also in agreement with the current understanding of the role of the "global ocean conveyor belt" for the uptake of anthropogenic CO2 into the deep ocean.