|
|
|
| Registros recuperados: 11 | |
|
| |
|
| |
|
|
| Kallel, N; Paterne, M; Duplessy, Jc; Vergnaudgrazzini, C; Pujol, C; Labeyrie, L; Arnold, M; Fontugne, M; Pierre, C. |
| Sea-surface temperature (SST) estimates for the last 10,000 years have been derived from foraminiferal fauna variations in ten cores from the Mediterranean Sea. For the eastern cores, modern analogs of fossil assemblages are found in the eastern Mediterranean Sea. In the Alboran and Tyrrhenian Seas, the bet analogs originate from modern fauna located either in the western Mediterranean Sea or in the North Atlantic Ocean. During the last sapropel event, centred at about 8,000 years B.P., SSTs were similar to present in the eastern basin, whereas they were colder than today by about 1.5 degrees C in the Alboran Sea and 2.5 degrees C in the Tyrrhenian Sea. Oxygen isotope measurements agree with ecological studies to show that Globigerina bulloides and... |
| Tipo: Text |
|
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20427/18094.pdf |
| |
|
|
| Delaygue, G; Bard, E; Rollion, C; Jouzel, J; Stievenard, M; Duplessy, Jc; Ganssen, G. |
| We analyze the surface sigma O-18 - salinity relationships of the Bay of Bengal and the Arabian Sea, in the northern Indian Ocean, known for their contrasting hydrological conditions. New measurements of these tracers show a very low sigma O-18 - salinity slope associated with the strong dilution in the Bay of Bengal, but a slope more typical of this latitude in the Arabian Sea. Although this region is marked by a complex monsoonal regime, numerical modeling using a box model and a general circulation model is able to capture the sigma O-18 - salinity slope and its geographical variation. Both models clearly show that the low sigma O-18 - salinity slope is due to the evaporation-minus-precipitation balance, with an important contribution of the continental... |
| Tipo: Text |
Palavras-chave: Indian Ocean; Ocean/atmosphere interactions; Paleoclimatology; Stable isotopes. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/00221/33225/31800.pdf |
| |
|
|
| Duplessy, Jc; Labeyrie, L; Juilletleclerc, A; Maitre, F; Duprat, J; Sarnthein, M. |
| We have developed a new method to reconstruct surface water salinity of the North Atlantic Ocean, based on a comparison between transfer function estimates of sea surface temperature and the oxygen isotope ratio of two common planktonic foraminiferal species, N. pachyderma (left coiling) and G. bulloides. We first used core-top analyses to demonstrate that, under modern conditions, the paleotemperatures determined from the isotopic composition of foraminiferal shells are linearly linked to the summer sea surface temperature only within a certain temperature range, characteristic of each species, which is termed the "optimum temperature range". We then used this information to derive an estimate of the isotopic composition and salinity of the North Atlantic... |
| Tipo: Text |
Palavras-chave: PALEO-OCEANOGRAPHY; PALEOCLIMATOLOGY; ISOTOPES; SALINITY; ATLANTIC OCEAN. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00101/21261/18872.pdf |
| |
|
|
| Pastouret, L; Chamley, H; Delibrias, G; Duplessy, Jc; Thiede, J. |
| The oxygen isotopes ratios of benthic foraminifera and detailed radiocarbon ages of the organic matter of an over 15 m long sediment core from the outer Niger delta allow us to date the oxygen isotope stage boundaries 1,2 to 11500 (+ 650) years BP. 2/3 to approximately 23000 (+ 2000) years BP. The composition of the predominantly terrigenous clays and accessory pelagic fossils reflects the evolution of the climate over the southwestern Sahel zone and the response of the Eastern Tropical Atlantic to these climatic fluctuations during the Late Quaternary. [NOT CONTROLLED OCR] |
| Tipo: Text |
|
| Ano: 1978 |
URL: http://archimer.ifremer.fr/doc/1978/publication-5227.pdf |
| |
|
| |
|
|
| Winguth, Ame; Archer, D; Duplessy, Jc; Maier-reimer, E; Mikolajewicz, U. |
| We use a carbon cycle model coupled to an ocean general circulation model to explore the links between sea surface boundary conditions, the deep-sea circulation, and the distribution of paleonutrient tracers (delta(13)C and Cd/Ca) from Last Glacial Maximum (21,000 B.P.) sediments. A glacial flow field with a shallower and 50% reduced North Atlantic overturning circulation generally reproduces the tracer data but cannot explain the strong glacial-interglacial shift in delta(13)C in the Southern Ocean. Sensitivity experiments with changes of +/-1 in salinity in the glacial salinity boundary fields show circulation patterns ranging from even stronger than the present day one to nearly a shutdown of the Atlantic deep-sea circulation. Our model results indicate... |
| Tipo: Text |
|
| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35061/34595.pdf |
| |
|
|
| 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 |
|
| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35058/34601.pdf |
| |
|
| |
| Registros recuperados: 11 | |
|
|
|
