PLATE 4b A slightly more complex representation of the global ocean circulation than in Plate 4a, simplified from Ganachaud and Wunsch (2000), as estimated from modern oceanographic data. The figure shows the integrated flow across the latitudes where observations were taken during the World Ocean Circulation Experiment (WOCE) in the 1990s. The red arrows designate near-surface flow (typically warm; technically, water density less than 1027.72 kg m-3), blue and green arrows are deep and bottom flows, respectively. Units are Sverdrups (million cubic meters per second); for comparison, the Gulf Stream transports around 31 Sverdrups northward through the Florida Strait. Notice the vigorous sinking in the North Atlantic and the near-complete absence of sinking in the North Pacific.