Regional Modeling of Antarctic Bottom Water Flows in the Key Passages of the Atlantic

Abstract

AbstractThe goal of this research is to modify and apply a version of high‐resolution three‐dimensional numerical model for simulations of bottom circulation and to study the flows of Antarctic Bottom Water in abyssal channels of the Atlantic Ocean using this model. We adjusted the Institute of Numerical Mathematics Ocean Model σ‐level ocean circulation model for several regions with intense bottom currents in abyssal channels. High vertical resolution near the seafloor allowed us to study the abyssal part of the ocean circulation, while high horizontal resolution is necessary for modeling currents in narrow underwater channels and fracture zones. We used our direct velocity measurements carried out at key points of the currents in the channels for verification of the model. This approach was applied in the regions with different seafloor topography: in the long and narrow Vema Channel with a strong bottom current and in several fracture zones of the Mid‐Atlantic Ridge with rough bathymetry. On the basis of simulated three‐dimensional velocity fields, we analyzed the spatial structure of the bottom currents along the entire length of the channels, determined maximum velocities at different sections, investigated the influence of the Ekman flux on the structure of the flows, and compared our model results with in situ observations. We also calculated the total transports of Antarctic Bottom Water through the fractures in several underwater ridges of the Atlantic Ocean.