July 12, 2021

Cross-equatorial flow through an abyssal channel under the complete Coriolis force: Two-dimensional solutions

The component of the Coriolis force due to the locally horizontal component of the Earth?s rotation vector is commonly neglected, under the so-called traditional approximation. We investigate the role of this ?non-traditional? component of the Coriolis force in cross-equatorial flow of abyssal ocean currents. We focus on the Antarctic Bottom Water (AABW), which crosses from the southern to the northern hemisphere through the Ceara abyssal plain in the western Atlantic ocean. The bathymetry in this region resembles a northwestward channel, connecting the Brazil Basin in the south to the Guyana Basin in the north. South of the equator, the AABW leans against the western continental rise, consistent with a northward flow in approximate geostrophic balance. The AABW then crosses to the other side of the abyssal channel as it crosses the equator, and flows into the northern hemisphere leaning towards the east against the Mid-Atlantic Ridge.