Figure 2

Distribution of τ (a) and dPb (b) in the Subtropical oceans around South Africa in 2019. (c) The mixing diagram of dPb was made using the data presented in the a and b panels. Distribution of τ (d) and dPb concentration (e) in 2010 from published literature^28,35 and the corresponding mixing diagram (f). The arrows show the idealised circulation patterns. The end members (τ and Pb) for AC (open circle) and STSW (black-filled circle) in the mixing plots were calculated from the average and standard deviation of the samples collected in different oceanic regions representing the respective water masses shown in the left panels. The bold black curve in the mixing diagram (c and f) indicates the mixing between absolute values of the two end-members. The dashed curves also indicate the mixing considering the standard deviation associated with the absolute values of the end-members (black corresponds to τ and brown corresponds 1/Pb). The dotted lines represent the contribution of AC water constructed considering both the range of τ (black) and 1/Pb (brown). The τ value for the AC in 2010 (f) was drawn based on the 2019 dataset.