Fig. 1
(a) Circulation scheme for the ETAO superimposed on the annual mean of the dynamic topography (MDT) for a 30-year period (1993–2022). Surface currents (solid arrows) and thermocline currents (dashed arrows) are depicted from Talley et al.21 and Marshall et al.22. The following currents are shown: the central, northern, and southern branches of the Southern Equatorial Current (cSEC, nSEC, and sSEC), the Gabon-Congo Undercurrent (GCUC), the Guinea Current (GC), the North Equatorial Countercurrent (NECC), the North Equatorial Undercurrent (NEUC), the South Equatorial Countercurrent (SECC), the South Equatorial Undercurrent (SEUC), and the Angola Current (AC). Additionally displayed are the Lüderitz cell (LC), the Guinea Dome, the Benguela Current (BC), the Angola Gyre, and the Angola-Benguela Frontal Zone (ABFZ). (b) shows the population of cities that are less than 10 m above sea level (from Nicholls et al.23) on a logarithmic scale over the ETAO, with the Gulf of Guinea (GoG, 8°W, 12°E; 2°N, 7°N) as the most exposed region. The acronyms EAUS, NBUS (20°W, 12°W; 10°N, 18°N) and SMUS (8°E, 16°E; 16°S, 28°S) stand for the Equatorial Atlantic Upwelling System, Namibian-Benguela Upwelling and the Senegal–Mauritania Upwelling respectively. The inset shows the position of the ETAO region along the tropical Atlantic.
