Reconstruction of South Atlantic Subtropical Gyre changes during Termination V and MIS 11: assessing (sub)surface temperature and salinity from trace-element analyses

• Grant number: 25/19280-0
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: December 10, 2025
• End date: June 04, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal Investigator: Marília de Carvalho Campos Garcia
• Grantee: Viviane Querollaine Pires Turman
• Supervisor: Mahyar Mohtadi
• Host Institution: Instituto de Geociências (IG). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: University of Bremen, Germany
• Associated to the scholarship: 24/14342-5 - Reconstruction of changes in the South Atlantic Subtropical Gyre during Termination V and the MIS11: a multi-proxy approach, BP.MS

Abstract

Subtropical gyres are the main pathways for energy redistribution between low and high latitudes, playing a crucial role in the global climate system. Over the past decades, observationaldata have recorded a southward displacement of the South Atlantic Subtropical Gyre (SASG). Thisphenomenon is linked to a systematic poleward migration of the extratropical atmosphericcirculation, likely influenced by the weakening of the Atlantic Meridional Overturning Circulation(AMOC), which leads to heat accumulation in the Southern Hemisphere and a consequent southward shift of the (sub)tropical climate belts. However, the limited duration of instrumental records hampers a deeper understanding of the trends underlying these changes. Paleoceanographicrecords from the western tropical Atlantic provide a unique opportunity to investigate SASGdynamics on longer time scales, as this region is directly influenced by its northern boundary. Theglacial termination that occurred around 430 thousand years ago, known as Termination V,culminated in the interglacial Marine Isotope Stage 11 (MIS 11), when global mean temperatureswere about 2°C higher than pre-industrial levels, providing a valuable reference period. This studyaims to reconstruct changes in the position of the SASG northern boundary during this interval byexamining the upper water column stratification in the western tropical Atlantic. To achieve this,relative abundance counts of planktonic foraminifera Globorotalia truncatulinoides and stable oxygen isotope analyses in G. truncatulinoides and Globigerinoides ruber albus have already been conducted. Preliminary results are promising and suggest variability in the SASG northern boundary position at both millennial and orbital time scales. Because upper ocean stratification depends on temperature and salinity, we propose to carry out Mg/Ca analyses on both planktonic species. Coupled with the existing d18O data, these results will allow us to disentangle the respective roles of temperature and salinity. To achieve this, a research stay at the Center for Marine Environmental Sciences - MARUM (University of Bremen, Germany) is planned. (AU)