Figure 3: Vertical profiles of tracer concentration upstream and downstream of the Drake Passage.

Measured tracer concentrations from observations at the UK2-68W stations (a,d) and UK2.5-SR1 stations (b,e) as well as from the model simulation results sampled at the locations of the UK2.5-SR1 stations (c,f). Concentrations in each panel are normalized by maximum concentration over their corresponding set of stations. The black lines are individual profiles at each station and the red lines are the averages over all individual profiles. (a–c) The profiles as a function of neutral density, while panels (d–f) show the same profiles as a function of depth. The mean profiles are mapped from density onto depth using the mean depth of isopycnals at each set of stations. The model tracer is initialized in density space with the mean observed profile at UK2 stations (red line in left-top panel). Time difference between UK2-68W and UK2.5-SR1 measurements was 120 days. For comparison, the model profiles are plotted in c,f 120 days after release along UK2-68W.