Search results for "Ocean"
showing 10 items of 2919 documents
The relationship between the Sahelian and previous 2nd Guinean rainy seasons: a monsoon regulation by soil wetness?
2002
The correlation of 0.61 found between observed July–September Sahelian rainfall in year 0 and September–November Guinean rainfall in year - 1, led us to explore the statistical relationships between precipitation, soil moisture and near surface Moist Static Energy (MSE) gradients in West Africa. These analyses were performed over successive 30-year periods and specifically, the most recent period between 1968–1998. It is shown from observations, National Centers for Environmental Predictions and National Center for Atmospheric Research (NCEP/NCAR) reanalyses and from the Global Soil Wetness Project (GSWP) database, that wet Sahelian rainy seasons are preceded by abnormally wet soils over th…
Distribution and ecology of the Globigerinoides ruber — Globigerinoides elongatus morphotypes in the Azores region during the late Pleistocene-Holoce…
2018
Abstract Globigerinoides ruber is the dominant taxon in the North Atlantic Subtropical Gyre, nowadays limited to the north by the Azores Current. It is highly sensitive to recent and late Pleistocene Azores Front Current System variability. In this study, we analyse the distribution of five individual morphotypes of the G. ruber – G. elongatus plexus (G. ruber s.s., G. ruber cyclostoma type, G. elongatus, G. elongatus cf.1, G. elongatus pyramidical type) and G. ruber kummerform gr. in a core (ATA13-OF-KT1) collected southwest of the Azores islands and located in a strategical position near the present-day boundary of the Subtropical Gyre/Azores Front Current System (STG/AFCS). Micropaleonto…
Assessing the potential long-term increase of oceanic fossil fuel CO2 uptake due to CO2-calcification feedback
2007
International audience; Plankton manipulation experiments exhibit a wide range of sensitivities of biogenic calcification to simulated anthropogenic acidification of the ocean, with the "lab rat" of planktic calcifiers, Emiliania huxleyi apparently not representative of calcification generally. We assess the implications of this observational uncertainty by creating an ensemble of realizations of an Earth system model that encapsulates a comparable range of uncertainty in calcification response to ocean acidification. We predict that a substantial reduction in marine carbonate production is possible in the future, with enhanced ocean CO2 sequestration across the model ensemble driving a 4?1…
Significant long-term increase of fossil fuel CO2 uptake from reduced marine calcification
2006
International audience; Analysis of available plankton manipulation experiments demonstrates a previously unrecognized wide range of sensitivities of biogenic calcification to simulated anthropogenic acidification of the ocean, with the "lab rat" of planktic calcifiers, Emiliania huxleyi not representative of calcification generally. We assess the implications of the experimental uncertainty in plankton calcification response by creating an ensemble of realizations of an Earth system model that encapsulates a comparable range of uncertainty in calcification response. We predict a substantial future reduction in marine carbonate production, with ocean CO2 sequestration across the model ensem…
Air-sea interaction in the Central Mediterranean: are surge-generating winds changing ?
2009
International audience; Hourly sea surges from the records of 9 French and 19 Italian tide-gauge stations have been computed and the wind directions corresponding to significant surge heights have been determined. The frequency of such surge-related wind directions tends to increase almost everywhere, while extreme wind speeds (that are most effective to produce high surges) tend generally to decrease; this may be a consequence of the northward displacement of storm trajectories on the European area. There is, however, an exception in the Gulf of Lions (the most westward area considered), where surge height may reach higher elevations, with a recent dangerous increase of southerlies
Changement climatique et surcotes marines, quel avenir pour les plages camarguaises ?
2012
2 pages; National audience
BIOGEOGRAPHY AND MACROECOLOGY OF ANTARCTIC AND SUB-ANTARCTIC ECHINOIDS USING A GEOGRAPHIC INFORMATION SYSTEM.
2010
participant; Many features already show how Polar seas are impacted by present-day global warming. To cope with new climate-induced changes and survive, Antarctic and Subantarctic marine organisms can either migrate or adapt to new prevailing conditions. New biotic interactions between Southernmost species and Subantarctic invaders can be expected, as new biogeographical distributions have already been documented. Because they are biologically and ecologically well diversified, echinoids play an important part in Antarctic benthic communities. Moreover, symbioses associated to cidarid echinoids make them even more crucial for benthic diversity. The biogeographical mapping of Antarctic echin…
Late Cretaceous changes in continental configuration: toward a better-ventilated ocean?
2017
International audience; Oceanic anoxic events (OAEs) are large-scale events of oxygen depletion in the deep ocean that happened dur-ing pre-Cenozoic periods of extreme warmth. Last global OAE occurred at the Cenomanian-Turonian boundary(OAE2) prior to the Late Cretaceous long term cooling. Ever since, and despite the occurrence of warming events,Earth no more experienced such large-scale anoxic conditions. Here we explore the role of major continentalconfiguration changes occurring during the Late Cretaceous on oceanic circulation modes through numerical sim-ulations using a General Circulation Model (GCM), that we confront to existing neodymium isotope data ("Nd).Except from a continuous d…
Mondes marins - Voyage insolite au cœur des océans.
2014
National audience; Tout l'équilibre de notre planète repose sur les océans, qui recouvrent plus de 70 % de la surface de la Terre. Mais que sait-on vraiment de ce monde des profondeurs ? Si, en quelques années, les connaissances ont progressé, l'environnement marin et les interactions complexes qui régissent son fonctionnement restent mal connus. Sait-on, par exemple, que dans cet immense réservoir de biodiversité, la grande majorité des espèces reste encore à identifier ? Que des organismes microscopiques y jouent des rôles essentiels, comme dans la formation des nuages ? Que les habitants des abysses y ont adopté des modes de vie surprenants leur permettant de tolérer des conditions toxiq…
Foreword for the thematic volume of the 8ISCPP. Recent advances in present and past cephalopod studies.
2012
3 pages, éditorial.; International audience