High precision Total CO2 (TCO2) data are presented from the NW Weddell Sea obtained during two cruises which were 3 years apart. A TCO2 increase from 1993 to 1996 was observed in the newly formed bottom water, whereas no TCO2 increase was found in the surrounding water masses. Accompanying this TCO2 increase in the bottom water was an oxygen decrease. Obviously, bottom water with variable characteristics is produced along the margins of the Weddell Sea. Examination of possible causes leads to the conclusion that the bottom water variability is largely due to varying amounts of Warm Deep Water intruding onto the shelves of the Weddell Sea, thus changing the shelf water end-member of bottom water formation. Analysis of the data, using the observed differences of oxygen to perform a correction, is suggesting that some part of the TCO2 increase of the bottom water is due to the increased level of anthropogenic CO2. The TCO2 increase of the bottom water is commensurate to a tentative annual increase of about 1 µmol kg-1 in the surface water source of this bottom water. This would agree fairly well with the increase of the partial pressure of CO2 in the atmosphere.
AWI Organizations > Climate Sciences > Climate Dynamics
AWI Organizations > Climate Sciences > Sea Ice Physics