Fig. 5: Schematic diagram (3-dim) of the AMOC across the OSNAP section and associated contribution to the density-space AMOC from the horizontal subpolar gyre circulation based on robust diagnostic calculation (RDC) results. | Communications Earth & Environment

Fig. 5: Schematic diagram (3-dim) of the AMOC across the OSNAP section and associated contribution to the density-space AMOC from the horizontal subpolar gyre circulation based on robust diagnostic calculation (RDC) results.

From: Horizontal circulation across density surfaces contributes substantially to the long-term mean northern Atlantic Meridional Overturning Circulation

Fig. 5

Colors of isopycnals (from RDC, dashed lines) and flow arrows indicate seawater density (light to dense: yellow-red-purple-violet-blue-dark blue). As in Fig. 1, the density of Atlantic inflow increases along the pathways of the cyclonic gyre. The black thick lines (isopycnals from RDC) denote the density level at which the maximum mean AMOC occurs in each subsection. Across OSNAP East, the lighter (denser) branch of the cyclonic gyre moves with a net northward (southward) transport above (below) the thick isopycnal, representing the important contribution of the horizontal subpolar gyre circulation to the density-space AMOC. The density contrast across OSNAP East is much larger than that across OSNAP West, consistent with a much stronger AMOC across OSNAP East than that across OSNAP West due to both thermal wind contribution and horizontal circulation contribution. Note only the upper ocean gyre is illustrated here as an example, but as shown in Fig. 4 the gyre also extends below the upper ocean.

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