On the Role of Bottom Pressure Torques in Wind-Driven Gyres

Abstract Previous studies have concluded that the wind-input vorticity in ocean gyres is balanced by bottom pressure torques (BPT), when integrated over latitude bands. However, BPT must vanish any area enclosed an isobath. This constraint raises ambiguities regarding regions which should close budget, and implies generated to balance a local wind stress curl necessitates generation of compensating, nonlocal thus circulation. study aims clarify role wind-driven using idealized isopycnal model. Experiments performed with single-signed enclosed, sloped basin reveal balances winds only Integrating other, dynamically motivated definitions gyre, such as barotropic streamlines, yields between frictional torques. friction plays nonnegligible structuring gyre Nonlocal manifest form along-slope gradients associated weak basin-scale circulation, are transition around coasts. Finally, suite perturbation experiments used investigate dynamics BPT. To predict BPT, authors extend previous theory describes propagation surface signals from interior toward coast along planetary potential contours. shown agree closely diagnosed contributions budget across model experiments.