The Impacts of the Atlantic Ocean´s Circulation on the Components of Heat Balance and Precipitation

• Ano de defesa: 2024
• Autor(a) principal: Rocha, Maurício Rebouças
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Atlantic Meridional Overturning Circulation; Calor Armazenado; Circulação de Revolvimento Meridional no Atlântico; Climate Change; Heat Storage; Heat Transport; Intertropical Convergence Zone; Mudanças Climáticas; Transporte de Calor; Zona de Convergência Intertropical
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/21/21135/tde-03102024-145403/

Conservation laws applied to the ocean dictate that the horizontal divergence of heat transport and heat exchange at the air-sea interface control the temporal variation of heat storage. In the Atlantic, the meridional heat transport is directed northwards, mainly due to the upper branch of the Atlantic Meridional Overturning Circulation (AMOC). Another pattern that reflects the large-scale thermodynamics patterns of the Atlantic is the Intertropical Convergence Zone (ITCZ), although its average position depends on local sea surface temperature (SST) anomalies or the trade winds convergence at the seasonal scale. As the connection between large-scale ocean circulation and precipitation changes over time, especially as the planet warms, this work aims to investigate the mechanisms that connect the ocean circulation in the South and tropical Atlantic with the components of heat balance and precipitation on different time scales. The first chapter of the thesis introduces the research topic. The second chapter assumes that the surface circulation in the tropical Atlantic drives the long-term trend of the SST and the average position of the ITCZ observed in recent decades. We conclude that the temperature transport generated by the North Equatorial Countercurrent and the northern branch of the South Equatorial Current explains interannual changes in the ITCZ. The third chapter explores the connection between the AMOC and the components of the South Atlantic heat balance in the present and future climate. The main conclusion is that changes in the upper cell of the AMOC lead to an increase in the heat storage rate in the South Atlantic for the period from 2015 to 2100. The fourth chapter investigates the connection of the interannual variability of the AMOC with the ITCZ. The conclusion is that in addition to long-term trends, periods of AMOC weakening are anti-correlated with maximum precipitation anomalies in the tropical South Atlantic in the climate change scenario. Finally, this thesis highlights the importance of local temperature transport by surface currents for the ITCZ, the importance of the AMOC for the warming of the South Atlantic in the future climate, and the impacts of the weakening phases of this circulation for positive anomalies of precipitation in the tropical South Atlantic.