Fig. 3: Model vertical shear and potential vorticity.

Model results after 20 days are shown for (a) plan view of the potential vorticity at 200 m depth (10^–8 m^–1 s^–1), for (b, c) vertical sections of the vertical shear of zonal velocity (s^–1), and (d, e) vertical sections of the potential vorticity (10^–8 m^–1 s^–1). The vertical sections shown in (b, e) are along the blue line in (a), and those in (c, d) are along the red line in (a). Contours in (a) are sea surface height (m) and contours in (b–e) represent isopycnals at every 0.5 kg m^–3. Model topography is shown as black in (b–e). The boundary of black shapes indicates 200-m isobath in (a). The box with the dashed black line represents the region of the observation during June 2018 shown in Figs. 4–6, and the white–black lines indicate the ship tracks for Leg b and Leg c in observation of November 2017 shown in Figs. 1 and 2.