SAGA: The South Atlantic Gateway in the Global Conveyor Belt

The general objective of the SAGA project is to quantify and monitor the returning limb of the Atlantic Meridional Overturning Circulation (AMOC) in the South Atlantic Ocean, with special attention to the interior-ocean zonal flows linking the eastern and western South Atlantic basins. The South Atlantic Ocean is a major component of the climate system, regulating the intensity of the AMOC. The circulation at depth controls the efficiency of the AMOC, connecting the North Atlantic Deep Waters with the Antarctic Bottom Waters; furthermore, the circulation patterns at the surface and intermediate layers control the returning limb of the AMOC, linking the very cold subducting regions of the Southern Ocean with the tropical and equatorial upwelling regions. Despite its regional and global relevance, the South Atlantic is a relatively unexplored region.

There are several research teams from United States, France, Great Britain, Germany and the riverine countries - mainly Argentina, Brazil and South Africa - that are focusing their efforts on the South Atlantic. The European Union, in the 2018-2020 working program for H2020, is endorsing an All Atlantic Ocean Research Alliance Flagship with special emphasis on the South Atlantic. Here we propose an ambitious, interdisciplinary and highly innovative coordinated effort to be carried out by three of the Spanish leading oceanography teams working in the Atlantic Ocean. This effort will analyse existing data, produce valuable new data sets, and will explore some principal physical and biogeochemical processes occurring in the South Atlantic Ocean. The field work will combine traditional and innovative measurements, complementing the ongoing international sampling efforts (through instrumented platforms and remote sensing) and numerical modelling. Field sampling will include two transoceanic cruises and the monitoring of zonal flows in the interior ocean, in a region that has been recently identified as a gateway for both the starting and returning limbs of the AMOC (South Atlantic GAteway, SAGA). In the SAGA proposal, interior ocean monitoring is planned for two years but its incorporation into ongoing European efforts would turn it into a permanent international observing array.

The SAGA project will reinforce the creation of a strong Spanish research team working on the physical and biogeochemical processes in the Atlantic Ocean, placing Spain at the forefront among those countries carrying out interdisciplinary research in the South Atlantic Ocean and strongly endorsing the proposing team towards the forthcoming H2020 and Horizon Europe calls.

Participating institutions: IOCAG (ULPGC); ICM (CSIC); COC (IEO).