Indirect investigations of the Atlantic Meridional Overturning changes in the South Atlantic Ocean in numerical models for the 20th century

• Main Author: Signorelli, Natália Tasso
• Other Authors: Wainer, Ilana Elazari Klein Coaracy
• Format: Master Thesis
• Language: English
• Published: Biblioteca Digitais de Teses e Dissertações da USP 2013
• Subjects: Antarctic Intermediate Water; Meridional Overturning Circulation; South Atlantic; South Atlantic Central Water; South Equatorial Current bifurcation; Antarctic; Curl; Antarc*; South Atlantic Ocean
• Online Access: http://www.teses.usp.br/teses/disponiveis/21/21135/tde-27032014-111133/

The South Atlantic has a relevant role on the AMOC variability as it includes two main conduits of its upper-ocean return flow: the NBUC and the IWBC that carry, mainly, the SACW and the AAIW and are originated from the bifurcation of the SEC. One of the hypotheses of this work is that analyzing the bifurcation variability it is possible to get an index of the AMOC changes. Another hypothesis is that in a global warming scenario, changes in the hydrological cycle would drive modifications in the water masses that are part of the AMOC, and thus, contribute to its variability. Four global model results were used, with different forcing and spatial resolution. Results show that changes in the bifurcation are linked to modications in the currents both caused by variations in the wind stress curl. Good correlations were found between the SEC bifurcation at the surface and the AMOC. The NBUC seems to be the link between them. Shallowing of the SACW core is related to an increase of the salinity on neutral surfaces. The AAIW is occupying less space in the water column due to an increasing of the salinity in the neutral surfaces at 11°S, while the opposite happens at 27°S The South Atlantic has a relevant role on the AMOC variability as it includes two main conduits of its upper-ocean return flow: the NBUC and the IWBC that carry, mainly, the SACW and the AAIW and are originated from the bifurcation of the SEC. One of the hypotheses of this work is that analyzing the bifurcation variability it is possible to get an index of the AMOC changes. Another hypothesis is that in a global warming scenario, changes in the hydrological cycle would drive modifications in the water masses that are part of the AMOC, and thus, contribute to its variability. Four global model results were used, with different forcing and spatial resolution. Results show that changes in the bifurcation are linked to modications in the currents both caused by variations in the wind stress curl. Good correlations were found between the SEC bifurcation at the surface and the AMOC. The NBUC seems to be the link between them. Shallowing of the SACW core is related to an increase of the salinity on neutral surfaces. The AAIW is occupying less space in the water column due to an increasing of the salinity in the neutral surfaces at 11°S, while the opposite happens at 27°S