A CHLOROFLUOROMETHANE AND HYDROGRAPHIC SECTION ACROSS DRAKE PASSAGE -DEEP-WATER VENTILATION AND MERIDIONAL PROPERTY TRANSPORT

New hydrographic and nutrient data obtained on a section across Drake Passage (F/S Meteor January 1990, World Ocean Circulation Experiment H ydrographic Program section SI) are in close agreement with property s ections reported previously. The chlorofluoromethanes CFM 11 and CFM 1 2 were measured in Drake Passage for the first time. CFM concentration s are found to decrease from the surface down into the Upper Circumpol ar Deep Water, for which they confirm water renewal from the south. Fo r the Lower Circumpolar Deep Water, in which CFM concentrations were a bove detection limit only south of the Polar Front, very little water renewal on the CFM time scale is implied. Nonvanishing CFM is again fo und in the Weddell Sea Deep Water and the Southeast Pacific Deep Water toward the bottom in the south, but recent ventilation for the latter water mass is rejected. CFM 11 and CFM 12 concentrations vary essenti ally in constant proportion down to very low concentrations, questioni ng the possibility of using CFM ratios as ''age'' markers. The observe d ratios are shown to be a natural feature of the upwelling regime of the southern ocean. Property concentrations on isopycnal surfaces disp lay large undulations, reaching down into the Upper Circumpolar Deep W ater. Their extrema, due to varying contribution of young water of sou thern origin, are situated at the boundaries of the current bands of t he Antarctic Circumpolar Current. The feature is ascribed to property advection by rings and is taken to support previous claims that rings are an important transport mechanism across the Antarctic Circumpolar Current and that they might assist in maintaining its fronts.