Evolution of the western South Atlantic circulation over the past 2000 years: insights for AMOC and wind-driven gyre variability

Abstract

This project proposes to investigate the paleoceanographic evolution of the western South Atlantic circulation with focus on the past 2,000 years (2k), at the LOCEAN-IPSL – Sorbonne Universit ´ e, under the supervision of Dr. Myriam Khodri, who is currently involved in past2k PMIP4-CMIP6 simulations, investigating the influence of external forcings on climate variability and change. Our goal is to reconstruct the past behavior of the upper limb of the Atlantic Meridional Overturning Circulation (AMOC) and the South Atlantic subtropical gyre (SASG) circulation in the western and subtropical South Atlantic with the latest paleoceanographic model simulation resources in order to shed light on our interpretation of the large-scale ocean circulation history, from past to future. The AMOC upper limb and the SASG are coupled up to the South Atlantic western boundary where their waters get meridionally split by the bifurcation of the southern South Equatorial Current (sSEC).This makes the sSEC bifurcation an useful fingerprint for simultaneous variations in the SASG and the AMOC. Therefore, it is expected to obtain a consistent framework for the temporal evolution of the sSEC bifurcation latitude (SBL) index in association with the strength of the north- and southward western boundary currents which are embedded in broader oceanographic contexts that associate to global scale changes. (AU)