Response of the upper water column at the origin of the Brazil Current to slowdown events of the Atlantic Meridional Ocean Circulation during the last 80 ka

Abstract

The Brazil Current (BC) transports a substantial amount of heat to the mid-latitudes of the South Atlantic through surface and central waters. It has been suggested that a slowdown interval of the Atlantic Meridional Ocean Circulation (AMOC) that occurred during the last deglaciation (i.e., Heinrich stadial 1 - HS1) produced a significant accumulation of heat and salinity in the BC. This would have strengthened summer precipitation over Brazil, most notably in the regions under the influence of the South Atlantic Convergence Zone. However, the response of the upper water column of the BC for other events of AMOC slowdown of the last glacial period remain unknown. Since HS can, to some extent, be considered past analogs of future conditions because a reduction of up to 44% in AMOC strength is expected to occur by the end of the century, a better understanding of the consequences that such slowdowns can produce in the upper water column is urgently required. This Master's project aims at reconstructing the paleoceanographic conditions (i.e., temperature, stratification, productivity) of the upper water column at the origin of the BC with high temporal resolution during the last 80 ka with special emphasis on HS. To achieve this aim, two marine sediment cores collected in the northeasthern Brazilian continental margin under the influence of BC will be investigated based on planktonic foraminifera assemblages and stable oxygen isotope analyses of planktonic foraminifera with apparent calcification depth in the central waters. (AU)