Constraining the overturning in the Pacific and Indian oceans by using boundary pressures

The ocean is a chaotic system where the presence of mesoscale eddies makes the understanding of basin or global scale flows difficult. However, the pressures on the continental shelves (boundary pressures) are only weakly influenced by eddies and, in most places, directly reflect the global scale processes. In this study, we use depth-integrated boundary pressure as a constraint to estimate the total upwelling in the Indian and Pacific oceans. The two main factors that determine the difference in the depth-integrated pressure between the east Pacific and the east Atlantic are the winds and the upwelling. Calculations from reduced-order theoretical models and diagnostics from 1/12th degree NEMO simulation show that, given the winds and boundary pressures, we can infer upwelling/downwelling in each ocean basin with errors of order 1 Sv. We apply this method using observations near eastern boundaries to put constraints on the total upwelling in the Pacific and Indian oceans.