Hydraulic Continuation of the Abyssal Flow From the Vema Channel in the Southwestern Part of the Brazil Basin

Abstract

AbstractIn 2013 and 2018, Shirshov Institute of Oceanology performed 12 stations with conductivity‐temperature‐depth and lowered acoustic Doppler current profiler (LADCP) profiling in the southwestern part of the Brazil Basin in order to find continuations of hydraulic controlled flow of the coldest Antarctic bottom water that propagates along the deepest bed of the Vema Channel. Comparison of these measurements with the historical database and our previous measurements in the Vema Extension region (27°S, 34°W) showed that such a continuation of the flow does not exist in the valley directed to the east, which seemed to be a topographic extension of the Vema Channel. Continuation of the flow was found over the section at 25°34′S across the meridionally oriented channel (depth up to 4,950 m) approximately along 33°30′W north of the Vema Extension region. Northward velocity speeds exceeding 35 cm/s were measured in the bottom flow (100–150 m thick above the bottom), which is displaced to the western slope of the meridional channel. Transport in the high‐speed core (velocity speed greater than 10 cm/s, potential temperature less than 0.62°C) in this channel was estimated at 0.150 ± 0.007 Sv on the basis of the LADCP measurements. There are several indirect indications of the formation of a local spillway (or a cascade of spillways) here in the regime of hydraulic control overflow.