Holocene shifts of the southern westerlies across the South Atlantic

Autor(es)

Voigt, Ines ^{[1, 2]} ; Chiessi, Cristiano M. ^[3] ; Prange, Matthias ^{[1, 2]} ; Mulitza, Stefan ^{[1, 2]} ; Groeneveld, Jeroen ^{[1, 2]} ; Varma, Vidya ^[4] ; Henrich, Ruediger ^{[1, 2]}

Afiliação do(s) autor(es)

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

^[2] Univ Bremen, Fac Geosci, D-28359 Bremen - Germany

^[3] Univ Sao Paulo, Sch Arts Sci & Humanities, Sao Paulo - Brazil

^[4] Stockholm Univ, Dept Meteorol, S-10691 Stockholm - Sweden

• Tipo de documento: Artigo Científico
• Fonte: PALEOCEANOGRAPHY; v. 30, n. 2, p. 39-51, FEB 2015.
• Citações Web of Science: 17

Resumo

The southern westerly winds (SWW) exert a crucial influence over the world ocean and climate. Nevertheless, a comprehensive understanding of the Holocene temporal and spatial evolution of the SWW remains a significant challenge due to the sparsity of high-resolution marine archives and appropriate SWW proxies. Here we present a north-south transect of high-resolution planktonic foraminiferal oxygen isotope records from the western South Atlantic. Our proxy records reveal Holocene migrations of the Brazil-Malvinas Confluence (BMC), a highly sensitive feature for changes in the position and strength of the northern portion of the SWW. Through the tight coupling of the BMC position to the large-scale wind field, the records allow a quantitative reconstruction of Holocene latitudinal displacements of the SWW across the South Atlantic. Our data reveal a gradual poleward movement of the SWW by about 1-1.5 degrees from the early to the mid-Holocene. Afterward, variability in the SWW is dominated by millennial scale displacements on the order of 1 degrees in latitude with no recognizable longer-term trend. These findings are confronted with results from a state-of-the-art transient Holocene climate simulation using a comprehensive coupled atmosphere-ocean general circulation model. Proxy-inferred and modeled SWW shifts compare qualitatively, but the model underestimates both orbitally forced multimillennial and internal millennial SWW variability by almost an order of magnitude. The underestimated natural variability implies a substantial uncertainty in model projections of future SWW shifts. (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
• Processo FAPESP: 10/09983-9 - Mudanças na temperatura da superfície do mar no oeste do Atlântico Sul e variabilidade na precipitação no sudeste da América do Sul desde o Último Máximo Glacial
• Beneficiário: Cristiano Mazur Chiessi
• Modalidade de apoio: Auxílio à Pesquisa - Regular