Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin

Autor(es)

Portilho-Ramos, Rodrigo da Costa ^{[1, 2]} ; Lima Pinho, Taina Marcos ^{[2, 3]} ; Chiessi, Cristiano Mazur ^[3] ; Barbosa, Catia Fernandes ^[4]

Afiliação do(s) autor(es)

^[1] Univ Bremen, MARUM Ctr Marine Environm Sci, Leobener Str, D-28359 Bremen - Germany

^[2] Univ Sao Paulo, Inst Geosci, Rua Lago 562, BR-05508080 Sao Paulo - Brazil

^[3] Univ Sao Paulo, Sch Arts Sci & Humanities, Rua Arlindo Bettio 1000, BR-03828000 Sao Paulo - Brazil

^[4] Univ Fed Fluminense, Dept Geoquim, Rua Outeiro Sao Joao Baptista S-N, BR-24020141 Niteroi, RJ - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Climate of the Past; v. 15, n. 3, p. 943-955, MAY 27 2019.
• Citações Web of Science: 0

Resumo

This study explores the mechanisms behind the high glacial productivity in the southern Brazilian margin (SBM) during the last 70 kyr using planktonic foraminifera assemblage and subsurface temperature information derived using the modern analogue technique. We show that enhanced glacial productivity was driven by the synergy of two mechanisms operating in different seasons: (i) enhanced productivity in the upwelling region during short austral summer events; and (ii) the persistent presence of the Plata Plume Water (PPW) due to prolonged austral winter conditions. We suggest that the upwelling systems in the southern Brazilian margin were more productive during the last glacial period due to the enhanced Si supply for diatom production by high-Si thermocline waters preformed in the Southern Ocean. We hypothesize that orbital forcing did not have a major influence on changes in upwelling during the last glacial period. However, the more frequent northward intrusions of the Plata Plume Water were modulated by austral winter insolation at 60 degrees S via changes in the strength of alongshore southwesterly winds. After the Last Glacial Maximum, the reduced Si content of thermocline waters decreased upwelling productivity, while lower austral winter insolation decreased the influence of the Plata PlumeWater over the southern Brazilian margin, reducing regional productivity. (AU)

• Processo FAPESP: 12/17517-3 - Resposta da porção oeste do Oceano Atlântico às mudanças na circulação meridional do Atlântico: variabilidade milenar a sazonal
• Beneficiário: Cristiano Mazur Chiessi
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Jovens Pesquisadores