Consistent picture of the horizontal circulation of the Atlantic Ocean over 3 decades

• Published in: Ocean science Vol. 19; no. 4; pp. 1009 - 1045
• Main Authors: Caínzos, Verónica, Pérez-Hernández, M. Dolores, Santana-Toscano, Daniel, Arumí-Planas, Cristina, Hernández-Guerra, Alonso
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 06-07-2023; Copernicus Publications
• Subjects: Abyssal zone; Antarctic Circumpolar Current; Atlantic Meridional Overturning Circulation (AMOC); Boundary currents; Brazil Current; Circulation; Complex systems; Convection; Convection processes; Deep layer; Freshwater; Heat; Heat transport; Hydrographic data; Inland water environment; Mass; Mid-ocean ridges; Ocean; Ocean circulation; Oceans; Salinity; Subtropical circulation; Temperature; Thermohaline circulation; Time series; Water circulation; Water column; Water currents; Water masses; Western boundary currents; United Kingdom > UK; United States > US; Atlantic Ocean
• ISSN: 1812-0792; 1812-0784; 1812-0792
• DOI: 10.5194/os-19-1009-2023

The circulation in the Atlantic Ocean is marked by the complex
system of pathways of the Atlantic Meridional Overturning Circulation
(AMOC). These currents change meridionally due to the interaction with
nearby water masses. Hydrographic data provide the opportunity to
characterize these currents for the whole water column with high-resolution
data over the last 30 years. Moreover, inverse methods enable the
quantification of absolute zonal transports across these sections,
determining the strength of each current at a certain latitude in terms of
mass, heat, and freshwater, as well as their transport-weighted temperature
and salinity. Generally, no changes can be found among decades for each of
the currents in terms of transport or their properties. In the South
Atlantic, the circulation describes the subtropical gyre affected by several
recirculations. There are nearly 61 Sv entering from the Southern and Indian
oceans at 45∘ S. The South Atlantic subtropical gyre exports
17.0 ± 1.2 Sv and around 1 PW northward via the North Brazil Current,
as well as −55 Sv southward at 45∘ S into the Antarctic Circumpolar
Current. In the North Atlantic, most of the transport is advected northward
via the western boundary currents, which reduce their strength as they take
part in convection processes in the subpolar North Atlantic, also reflected
in the northward progress of mass and heat transport. Deep layers carry
waters southward along the western boundary, maintaining similar values of
mass and heat transport until the separation into an eastern branch crossing
the mid-Atlantic Ridge in the South Atlantic. Abyssal waters originating in
the Southern Ocean are distributed along the South Atlantic mainly through its
western subbasin, flowing northward up to 24.5∘ N, subjected to an
increasing trend in their temperature with time.