The South Atlantic Ocean circulation and its variability at different scales

• Main Author: Manta, Gastón
• Other Authors: Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL), Dynamique et physique de l’atmosphère et de l’océan (DPAO), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X), Université Paris sciences et lettres, Sabrina Speich, Marcelo Barreiro Co-encadrant
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Heat transport; Mesoscale eddies; Shelf water export; Coupled variability; Transport de chaleur; Tourbillons à mésoéchelle; Exportation de l’eau du plateau; Variabilité couplée; [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; [SDE]Environmental Sciences; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; South Atlantic Ocean
• Online Access: https://theses.hal.science/tel-04597595; https://theses.hal.science/tel-04597595/document; https://theses.hal.science/tel-04597595/file/Manta_2022_These.pdf

The ocean, like the atmosphere, is a key component of the climate system redistributing heat from lower to higher latitudes. Also, it has absorbed the majority of the anthropogenic heat through its large heat capacity. The Atlantic Meridional Overturning Circulation (AMOC) is the main mechanism in how the ocean redistributes heat and other properties across this basin. The AMOC has historically received special attention in its northern basin due to its large contribution to the global circulation and influence over the climate in Europe and North America. Over the last decade, the efforts to observe the global ocean and in particular the South Atlantic have increased, as this basin has the unique characteristic to export heat to the northern hemisphere across the equator and it connects the AMOC with the other ocean basins. This Ph.D. thesis aims to understand new insights from the South Atlantic Ocean circulation from a physical oceanography perspective, using the exponentially growing number of observations provided by the deployment of Argo floats, ship-based hydrography, and satellite observations. The study uses different new analyses applied to the ocean and to a recently released atmospheric reanalysis. The Ph.D. work has focussed on three different aspects of the South Atlantic Circulation. In the first part, it has aimed to assess the meridional volume, freshwater, and heat (MHT) transports at 34.5°S in the South Atlantic in the first GO-SHIP hydrographic transect at this latitude that took place in January 2017. An upper and an abyssal overturning cell are identified with a strength of 15.64 ± 1.39 Sv and 2.4 ± 1.6 Sv, respectively. The net northward MHT is 0.27 ± 0.10 PW, increasing by 0.12 PW when we remove the observed mesoscale eddies with a climatology derived from the Argo floats data set. We attribute this change to an anomalous predominance of cold-core eddies during the cruise period. The zonal changes in water masses properties and velocity denote the imprint of exchange pathways with both ...