The Interconnected Dynamics of Antarctic Circulation and Its Effects on the South Atlantic MOC

• Grant number: 24/22849-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: February 28, 2026
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Physical Oceanography
• Principal Investigator: Olga Tiemi Sato
• Grantee: Daniel Alcântara Barretto Gontijo
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The proposed research aims to investigate the variability of meridional volume transport associated with the Atlantic Meridional Overturning Circulation (AMOC) at 34.5°S, where the South Atlantic Meridional Overturning Circulation Basin-wide Array (SAMBA) is located, focusing on the influence of flows originating from the Drake Passage and Good Hope. This study area is strategically significant as it represents critical points where the AMOC's meridional transport is strongly influenced by the convergence of flows from the Southern Ocean. These flows, in turn, result from fluctuations originating in the Pacific or Indian Oceans, modulated by the Antarctic Circumpolar Current (ACC). The activities include determining vertical sections of temperature and salinity at the boundaries of the study area. Initially, annual and monthly mean data from the World Ocean Atlas will be used to establish the region's climatological pattern. Subsequently, these data will be employed to validate in situ measurements collected using Expendable Bathythermographs (XBT) in the AX22 section (Drake Passage) and the AX25 section (Good Hope), which offer high spatial resolution sampling. The XBT sections will be compared with outputs from various numerical models to identify the one that best represents the regional thermohaline structure. Based on the selected model, time series analyses of AMOC volume transport at 34.5°S, as well as at the Drake and Good Hope sections, will be conducted to investigate the correlations between the ACC and the AMOC. These results will contribute to a better understanding of the connection between dynamic processes in Antarctica and the South Atlantic and their impacts on the global climate system.