Figure 5. Regional time series of summer pycnocline stratification and mixed layer depth anomaly.

(a) Summer climatological mixed layer depth, as in Fig. 2e, with three specific regions of interest outlined by red contours: North Atlantic (A); North Pacific (B); and Southern Ocean (C). For each of these regions, summer stratification anomaly times series and associated trends are respectively displayed in panels (b,d,f); and summer mixed layer depth anomaly times series and associated trends are respectively displayed in panels (c,e,g). Note that a negative depth anomaly refers to a deepening. Each times series panel shows: in thin gray line, the annual median percentage anomaly (from the local climatological seasonal cycle), computed for each individual observation; the errorbars refer to the 33-66 percentile range of percentage anomaly (errorbars are shown in black (gray) when more (fewer) than 50 data points are used in the annual statistics); the associated 5-year smoothed median time series is superimposed in blue; a linear trend from 1970-2018 is shown by the red line if greater than twice its standard error.