Data/hora: 03/06/2024 07:37:50

Provedor de dados: 	5	
País: 	France	
Título: 	Structure of the upper water column in the northwest North Atlantic: Modern versus last glacial maximum conditions	
Autores: 	De Vernal, A; Hillaire-marcel, C; Peltier, Wr; Weaver, Aj.	
Data: 	2002-10	
Ano: 	2002	
Palavras-chave: 	Last Glacial Maximum; LGM; North Atlantic; Salinity; Density; Pycnocline.	
Resumo: 	During the Last Glacial Maximum, the northwestern North Atlantic constituted a major conduit for Labrador and Greenland ice sheet meltwaters. Vertical density gradients in its upper water masses have been reconstructed by combining information from transfer functions based on dinocysts and from oxygen isotope measurements (delta(18)O) in planktonic foraminifera. Transfer functions yield temperature and salinity and thus potential density (sigma(theta)) for the warmest (August) and coldest (February) months in the photic zone. The delta(18)O values in different size fractions of epipelagic (Globigerina bulloides) and mesopelagic (Neogloboquadrina pachyderma left-coiled (Np1)) foraminifera allow us to assess sigma(theta) gradients through the pycnocline between surface and intermediate waters, based on the calibration of a sigma(theta) versus delta(18)O relationship from transfer function reconstructions. The size and density of Np1 shells provide further constraints on these sigma(theta) gradients. The results show the development of a very strong pycnocline during the LGM with a difference of about 3 (summer) to 1.5 (winter) sigma(theta) units between surface and underlying waters. They indicate conditions unfavorable for vertical convection and support the hypothesis of the spreading of a shallow, low-salinity buoyant layer over the northern North Atlantic. This layer depicted a strong E-W gradient, with maximum seasonal contrast and minimum absolute sigma(theta) values westward.	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	https://archimer.ifremer.fr/doc/00223/33405/31861.pdf

DOI:10.1029/2001PA000665

https://archimer.ifremer.fr/doc/00223/33405/	
Editor: 	Amer Geophysical Union	
Formato: 	application/pdf	
Fonte: 	Paleoceanography (0883-8305) (Amer Geophysical Union), 2002-10 , Vol. 17 , N. 4 , P. 2.1-2.15	
Fonte: 	Copyright 2002 by the American Geophysical Union.

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