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Master's Dissertation
DOI
Document
Author
Full name
Lucas Carnier Casaroli
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2019
Supervisor
Committee
Sato, Olga Tiemi (President)
Carvalho, Lino Augusto Sander de
Ambrizzi, Tercio
Title in Portuguese
Influência das variações de baixa frequência da Circulação de Revolvimento Meridional na concentração de clorofila - a no Atlântico Sul
Keywords in Portuguese
Circulação de Revolvimento Meridional
clorofila
multidimensional empirical mode decomposition
nitrato
Oscilação Antártica/El Niño-Oscilação Sul
teleconexões atmosféricas
variação interanual
Abstract in Portuguese
Em escalas interanuais a advecção de calor, sal e nutrientes pode afetar a produtividade primária. Pode-se citar a Circulação de Revolvimento Meridional (MOC) no impacto da concentração de clorofila. Neste estudo, a partir do método Multidimensional Empirical Mode Decomposition foram obtidos tendências decadais de PAR, nitrato integrado na coluna d'água, concentração de clorofila e fluxo de volume da MOC. Em variações de baixa frequência há uma relação entre o transporte de volume da MOC com o nitrato integrado na coluna d'água no Atlântico Sul, e consequentemente, na concentração de clorofila. Dois possíveis cenários foram identificados sobre o efeito da MOC no nitrato integrado e na concentração de clorofila. O cenário 1 apresenta uma relação direta no sistema MOC-nitrato integrado-concentração de clorofila, enquanto o efeito do cenário 2 é indireto, com a MOC afetando outras variáveis que perturbam o sistema. Neste estudo também foi analisado a influência de teleconexões atmosféricas na MOC do Atlântico Sul. Foi achado indícios da influência da Oscilação Antártica na MOC do Atlântico Sul em escalas decadais. Conclui-se que variações de baixa frequência no fluxo de volume da MOC alteram o padrão espaço-temporal da concentração de clorofila no Atlântico Sul.
Title in English
Influence of the low frequency variability of the Meridional Overturning Circulation over the South Atlantic chlorophyll - a concentration
Keywords in English
Antarctic Oscillation/El Nin?o-Southern Oscillation
atmospheric teleconnections
chlorophyll
interannual variability
Meridional Overturning Circulation
multidimensional empirical mode decomposition
nitrate
Abstract in English
On interannual timescales the advection of heat, salt and nutrients can affect the primary production. The influence of the Meridional Overturning Circulation (MOC) over the chlorophyll concentration can be mentioned. In this study, decadal trends of PAR, integrated nitrate over the water column, chlorophyll and volume flux of the MOC were obtained using the Multidimensional Empirical Mode Decomposition method. On low frequency variations there is a relationship between the MOC volume transport with integrated nitrate over the water column in the South Atlantic, and therefore, on chlorophyll concentration. Two scenarios were identified as possible mechanisms of influence of the MOC over integrated nitrate and chlorophyll concentrations. Scenario 1 presents a direct relationship on the system MOC-integrated nitrate-chlorophyll concentration, while scenario 2 has an indirect effect, with the MOC affecting other variables that disturb the system. In this study the influence of atmospheric teleconnections on the South Atlantic MOC were also investigated. It was found evidence that the Antarctic Oscillation can affect the South Atlantic MOC on decadal timescales. It was concluded that low frequency variability on the volume flux of the MOC can alter the spatiotemporal pattern of the chlorophyll concentration on the South Atlantic.
 
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Publishing Date
2019-05-27
 
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