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Master's Dissertation
DOI
10.11606/D.21.2018.tde-09042018-112125
Document
Author
Full name
Martim Mas e Braga
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Wainer, Ilana Elazari Klein Coaracy (President)
Ambrizzi, Tercio
Mata, Mauricio Magalhaes
Title in English
Frontal system changes in the Southeastern Atlantic Ocean
Keywords in English
Agulhas Leakage
Subtropical Front
Subtropical Gyre
Supergyre
Abstract in English
The transition between the South Atlantic and the Southern Ocean is marked by a frontal system that includes both the South Atlantic Current and the Antarctic Circumpolar Current (ACC). In the eastern part of the basin the latitudinal position of the fronts that compose this system is thought to control the input of warm waters into the Atlantic basin through the Agulhas Leakage. Changes in the Subtropical and Polar regimes associated with the system that marks the boundary between the Subtropical Gyre and the ACC are investigated using the simulation results of the ocean component of the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM), POP2. Sea surface height gradients and specific contours are used to identify and track the ocean fronts position. We compare the Subtropical Front position at the eastern edge of the South Atlantic to changes in temperature and salinity, as well as Agulhas Current transports and the overlying wind field, in order to determine what could be driving frontal variability at this region and its consequences to volume transport from the Indian into the Atlantic. Results suggest that the Subtropical Front is not the southern boundary of the subtropical gyre, but it responds to changes in the "Supergyre", especially the Indian Ocean Subtropical Gyre expansion.
Title in Portuguese
Mudanças no Sistema Frontal nas Altas Latitudes do Oceano Atlântico Sudeste
Keywords in Portuguese
Frente Subtropical
Giro Subtropical
Supergiro
Vazamento das Agulhas
Abstract in Portuguese
A transição entre os oceanos Atlântico Sul e Austral é marcada por um sistema frontal que inclui tanto a Corrente do Atlântico Sul quanto a Corrente Circumpolar Antártica (CCA). Na porção oeste da bacia, acredita-se que a posição meridional das frentes que compõem este sistema controla o aporte de águas quentes para o Atlântico pelo Vazamento das Agulhas. Mudanças nos regimes subtropical e polar associadas ao sistema que marca o limite entre o giro subtropical e a CCA são investigadas através dos resultados da componente oceânica do modelo do National Center for Atmospheric Research (NCAR), o Community Earth System Model (CESM). O gradiente meridional, bem como valores específicos de altura da superfície do mar são usados para identificar e acompanhar a posição destas frentes oceânicas. A comparação da posição da Frente Subtropical no limite leste do Atlântico Sul com as mudanças na temperatura e salinidade, assim como no transporte da Corrente das Agulhas e do campo de ventos sobrejacente, é feita para determinar quais as forçantes da variabilidade frontal nesta região e suas consequências no transporte de volume entre o Índico e o Atlântico. Resultados sugerem que a Frente Subtropical não é o limite sul do giro subtropical, mas responde às mudanças no "Supergiro", especialmente à expansão do Giro Subtropical do Oceano Índico.
 
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Publishing Date
2018-04-09
 
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