Transport variability of the North Atlantic deep water in the South Atlantic

Abstract

The SAGA (South Atlantic GAteway) project aims to quantify and monitor the return limb of the Atlantic Meridional Overturning Circulation (AMOC). As part of this project, three moorings have been deployed along the 10ºW in the South Atlantic from 21º to 31ºS. This area has been recently identified as the Atlantic Gateway, serving as an observatory for the starting and returning branches of the AMOC. Each mooring includes two MicroCat Conductivity-Temperature (CT), two Nortek Aquadop, four Anderaa SeaGuard, and one Anderaa RCM11. Data were collected over 2 years and one month in the approximate depth range of 1950 to 4000 m, thus characterizing the North Atlantic Deep Water (NADW) along the Mid-Atlantic Ridge (MAR). This study analyzed data from Mooring 1 (31.5ºS, 9.9ºW) and Mooring 2 (27.4ºS, 9.85ºW), showing predominant flow directions towards the west-southwest and northwest, respectively. It was also observed that the presence of Rossby waves explains part of the large-scale variability in the current velocity signals. Finally, it was highlighted that bathymetry influences the measurements at both moorings