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| De Vernal, A; Hillaire-marcel, C; Peltier, Wr; Weaver, Aj. |
| 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... |
| Tipo: Text |
Palavras-chave: Last Glacial Maximum; LGM; North Atlantic; Salinity; Density; Pycnocline. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33405/31861.pdf |
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| Solignac, S; Giraudeau, J; De Vernal, A. |
| Holocene records of sea surface conditions in the western Nordic seas were obtained from quantitative reconstructions based on dinoflagellate cyst assemblages. Two sediment cores from the east Greenland and the north Iceland shelves provide a detailed account of the long- and short-term dynamics of the opposing flows of Arctic versus Atlantic waters. Both marker species and quantitative reconstructions depict an overall trend toward warmer winter temperatures, saltier surface waters, and decreased sea ice extent. The latter is supported by a close relationship between relative abundances of an Atlantic dinocyst species, Nematosphaeropsis labyrinthus, and ice-rafted debris (IRD) records. We propose that the late Holocene increased IRD delivery in the... |
| Tipo: Text |
Palavras-chave: Holocene; North Atlantic; Sea-surface conditions. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34573/33124.pdf |
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| Pinot, S; Ramstein, G; Marsiat, I; De Vernal, A; Peyron, O; Duplessy, Jc; Weinelt, M. |
| Recent reconstructions of Sea-Surface Temperatures (SSTs) for the Last Glacial Maximum (LGM, 21 kyr BP) based on foraminifera and dinoflagellate proxies suggest that the north Atlantic may have been warmer than estimated by CLIMAP [1981]. To better understand the impact of such a warm north Atlantic on the global LGM climate, we used two different AGCMs to perform sensitivity studies. With the new, warmer SSTs, both models simulate a hydrological cycle and temperatures very different from those obtained with the CLIMAP boundary conditions. The most noticeable differences occur in winter over North America and Siberia whereas southern Europe is only weakly affected at all seasons. Whichever the conditions prescribed over the north Atlantic, both models... |
| Tipo: Text |
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| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35058/34601.pdf |
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