Éditeur(s) : The Oceanography Society
Résumé : Data assembly and processing centers are essential elements of the operational oceanography infrastructure. They provide data and products needed by modeling and data assimilation systems; they also provide products directly usable for applications. This paper discusses the role and functions of the data centers for operational oceanography. It describes some of the main data assembly centers (Argo and in situ data, altimetry, sea surface temperature) developed during the Global Ocean Data Assimilation Experiment. An overview of other data centers (wind and fluxes, ocean color, sea ice) is also given. Much progress has been achieved over the past 10 years to validate, intercalibrate, and merge altimeter data from multiple satellites. Accuracy and timeliness of products have been improved, and new products have been developed. The same is true for sea surface temperature data through the Global High-Resolution Sea Surface Temperature Pilot Project. A breakthrough in processing, quality control, and assembly for in situ data has also been achieved through the development of the real-time and delayed-mode Argo data system. In situ and remote-sensing data are now systematically and jointly used to calibrate, validate, and monitor over the long term the quality and consistency of the global ocean observing system. Main results are illustrated. There is also a review of the development and use of products that merge in situ and remote-sensing data. Future issues and main prospects are discussed in the conclusion.
Oceanography (1042-8275) (The Oceanography Society), 2009-09 , Vol. 22 , N. 3 , P. 56-69

Droits : 2009 The Oceanography Society
http://archimer.ifremer.fr/doc/2009/publication-6879.pdf
http://archimer.ifremer.fr/doc/00000/6879/

Éditeur(s) : Yale University
Résumé : Sea-surface temperature images of the coastal upwelling regions off Northwest Africa show that the core of upwelling is sometimes located far from the coast. This has been documented in three regions that share a common feature, namely a wide and shallow continental shelf. This upwelling feature plays a key role in the ecology of the Canary Current System. It creates an innerfront which provides retention for biological material, e.g. fish eggs and larvae, in the highly productive nearshore environment. An analytical model has been developed based on a two dimensional extension of Ekman's solution. The linear and steady response of a homogeneous ocean forced by an upwelling-favorable wind provides a mechanism for the upwelling separation from the coast. The merging of the surface and bottom Ekman layers induces a very weak cross-shore circulation and a "kinematic barrier" for the Ekman transport divergence. In the case of an alongshore wind, the barrier is located near the isobath h ≈ 0.4D, where D is the thickness of Ekman layers. This yields an upwelling cell which is essentially concentrated in the region 0.5D < h < 1.25D, with upwelling occurring preferentially near the isobath h ≈ 0.6D. It turns out that the cross-shore width of upwelling scales with D/S, the ratio of Ekman depth to bottom topographic slope. The application of this solution to real bathymetric profiles rationalizes, not only the offshore upwelling observations in Northwest Africa, but also the influence of topography on the cross-shelf structure of a wind-driven coastal upwelling. The model also quantifies the effect of the cross-shore wind component showing how it drives the nearshore pressure gradient adjustment and how it affects the upwelling. A linear numerical experiment reproduces the theoretical steady solution, thereby allowing investigation of the transient regime. Relaxation of the hypothesis in the numerical model validates the linear assumption of the theory and then allows investigation of the sensitivity to friction parameterizations and the influence of stratification. The latter leads to an "oscillation" of the upwelling cell with seaward migration driven by outcropping and homogeneization of the water column, and, coastal incursion driven by a "boundary layers splitting" process caused by shoreward advection of the isopycnal dome and stratification of the inner shelf.
Journal of Marine Research (Yale University), 2008-09 , Vol. 66 , N. 5 , P. 589-616

Droits : 2008 Yale University
http://archimer.ifremer.fr/doc/2008/publication-6334.pdf
DOI:10.1357/002224008787536790
http://archimer.ifremer.fr/doc/00000/6334/

Résumé : Preliminary analysis of the impact of an environmental change on ichtyologic fauna marinates and fishing in Guyanese water enter within the framework of the program CHALOUPE (dynamic Change of the exploited marine biodiversity and the viability of the Fisheries) coordinated by Ifremer Cayenne and financed by the ANR (National Agency of Research). The study focuses on: -analysis temporal variations of various environmental parameters (sea surface temperature and salinity, the phenomenon El Niño) -fish physical characteristics (tolerances of temperature and salinity, maximum height, distribution…) - analysis of the unloadings per unit of effort of the inshore fishing and an economic analysis of the selling price of fish Data are found on data bases and are given by scientists. The statistical studies and the cartographic representations show that there is an increase in temperature of water in Guiana since the end of the Nineties. The model AquaMaps® simulates the potential consequences of this reheating on the fish distribution. Certain stocks of fishing are weakened. For the moment, if the composition of the captures of inshore fishing changes, that seems more due to a change of fishing strategy than due to an impact of the climatic change. In addition, the average value of the capture increased for reason commercial.
Les analyses de l’impact d’un changement environnemental sur la faune ichtyologique marine et la pêche dans les eaux guyanaises entrent dans le cadre du programme CHALOUPE (CHAngement gLObal, dynamiqUe de la biodiversité marine exploitée et de la viabilité des Pêcheries) coordonné par l’Ifremer Cayenne et financé par l’ANR (Agence Nationale de la Recherche). L’étude porte sur : -l’analyse des variations temporelles de différents paramètres environnementaux (température et salinité de surface des eaux, le phénomène El Niño) à l’échelle de quelques décennies -les caractéristiques physiques des poissons (tolérances de températures et de salinité (taille maximum, répartition…) ; -l’analyse des débarquements par unité d’effort de la pêche côtière depuis les années 70 ; -une analyse économique de la pêche ; Les données sont récoltées à partir de bases de données et au près de différents chercheurs. Les études statistiques et les représentations cartographiques démontrent qu’il y a bien une augmentation de température des eaux en Guyane depuis la fin des années 90. Le modèle statistique sous AquaMaps® permet de simuler les conséquences potentielles de ce réchauffement sur la répartition des poissons. Dans un tel contexte, certains stocks de pêche sont fragilisés. Pour le moment, si la composition des captures de la pêche côtière se modifie dans le même temps, cela semble plus du fait de changement de stratégie de pêche que du fait de l’impact du changement climatique. Par ailleurs, la valeur moyenne de la capture a augmenté pour des raisons commerciales.

Droits : 2006 Ifremer
http://archimer.ifremer.fr/doc/00077/18855/16429.pdf
http://archimer.ifremer.fr/doc/00077/18855/

Éditeur(s) : HAL CCSD
Résumé : This paper studies the biological and economic effects of globalwarming on the French Guiana shrimp …fishery. The sea surface tem-perature is explicitly introduced into four natural growth functions,among which the Cobb-Douglas function best adjusts the availabledata. Besides, a Cobb-Douglas harvest function is also estimated, in-dicating that shrimp production in French Guiana is highly sensitive tothe shrimp stock, which implies that global warming may have strongeconomic implications. We …nally consider a centralized resource man-agement of the French Guiana shrimp …shery, that is undertaken invarious trend scenarios concerning the sea surface temperature. Un-der the most plausible scenario, in which the sea surface temperaturefollows the trend of the last decades, pro…ts and biomass respectivelydecrease and collapse around the end of the 2020’s.
https://hal.univ-antilles.fr/hal-01243305

hal-01243305
https://hal.univ-antilles.fr/hal-01243305
https://hal.univ-antilles.fr/hal-01243305/document
https://hal.univ-antilles.fr/hal-01243305/file/Diop%20et%20al.%20%282015%29.pdf

Éditeur(s) : HAL CCSD Inter-Research
Résumé : International audience
The effects of global change are particularly serious in areas where range shiftsof species are physically constrained such as the Ligurian Sea, which is one ofthe coldest sectors of the Mediterranean. In this basin, historical informationon water temperature (from the sea surface down to 75 m depth) dates backto the 1950s. Early studies also recorded warm-water species occurrence.Thanks to these data we provide the first detailed characterization of watertemperature variation from 1958 up to 2010 in the layer 0–75 m depth. Wecoupled this analysis with the available information on rocky reef epibenthiccommunities (literature review from 1955 to 1964 and field data from 1980 to2010). The analysis of water temperature revealed several patterns of variation:a cooling phase from 1958 to 1980, a phase of rapid warming from 1980 to1990 and a phase of slower warming from 1990 to 2010. Inter-annual variationin temperature increased over the entire period for the water layer down to20 m. Warm-water native and alien species richness increased during thewarming phases. Literature estimates suggest a decrease in warm-water nativespecies richness during the cooling phase. The analysis of quantitative data collectedin the early 1990s and late 2000s indicated a decrease in the cover ofwarm-water native species on shallow rocky reefs and an increase in deeperwaters. We argue that increased inter-annual variation in water temperaturemay disadvantage native warm-water species in shallow waters. Our resultsindicate that the effect of temperature rises in cold, constrained basins may bemore complex than the simple prediction of species changing their geographicalrange according to their thermal limits.
Marine Ecology Progress Series

hal-01239259
https://hal-univ-perp.archives-ouvertes.fr/hal-01239259
DOI : 10.1111/maec.12277

Éditeur(s) : Copernicus Gesellschaft Mbh
Résumé : From 10 to 8 ka BP (thousand years before present), paleoclimate records show an atmospheric and oceanic cooling in the high latitudes of the Southern Hemisphere. During this interval, temperatures estimated from proxy data decrease by 0.8 degrees C over Antarctica and 1.2 degrees C over the Southern Ocean. In order to study the causes of this cooling, simulations covering the early Holocene have been performed with the climate model of intermediate complexity LOVECLIM constrained to follow the signal recorded in climate proxies using a data assimilation method based on a particle filtering approach. The selected proxies represent oceanic and atmospheric surface temperature in the Southern Hemisphere derived from terrestrial, marine and glaciological records. Two mechanisms previously suggested to explain the 10-8 ka BP cooling pattern are investigated using the data assimilation approach in our model. The first hypothesis is a change in atmospheric circulation, and the second one is a cooling of the sea surface temperature in the Southern Ocean, driven in our experimental setup by the impact of an increased West Antarctic melting rate on ocean circulation. For the atmosphere hypothesis, the climate state obtained by data assimilation produces a modification of the meridional atmospheric circulation leading to a 0.5 degrees C Antarctic cooling from 10 to 8 ka BP compared to the simulation without data assimilation, without congruent cooling of the atmospheric and sea surface temperature in the Southern Ocean. For the ocean hypothesis, the increased West Antarctic freshwater flux constrainted by data assimilation (+100 mSv from 10 to 8 ka BP) leads to an oceanic cooling of 0.7 degrees C and a strengthening of Southern Hemisphere westerlies (+6 %). Thus, according to our experiments, the observed cooling in Antarctic and the Southern Ocean proxy records can only be reconciled with the reconstructions by the combination of a modified atmospheric circulation and an enhanced freshwater flux.
Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2013 , Vol. 9 , N. 2 , P. 887-901

Droits : Author(s) 2013. CC Attribution 3.0 License.
http://archimer.ifremer.fr/doc/00181/29203/27584.pdf
DOI:10.5194/cp-9-887-2013
http://archimer.ifremer.fr/doc/00181/29203/

Éditeur(s) : Gauthier-villars
Résumé : 69 new hydrothermal sites were discovered during the Naudur diving cruise. Dives were conducted between 17 degrees 5 and 18 degrees 40'5 on four segments showing marked contrast in morphology, volcanic, tectonic and hydrothermal activity. At 17 degrees 10'5, 17 degrees 25'5 and 18 degrees 37'5 the ridge has a dome shaped cross-section and is dominated by very active volcanic activity. Early widespread low temperature (<50 degrees C) diffuse hydrothermal discharge is followed by focused high temperature black smokers. At 18 degrees 15'S tectonic activity is dominant, no recent lava was observed, and only two of the 20 hydrothermal sites are active. At 18 degrees 32'5 recent lava representing a new volcanic episode partly covers the bottom of the graben. Deep hydrothermal convection is reactivated with new black smokers along the graben wall. Also, there is low temperature shimmering water from cooling lava flows. These three segments can be considered as successive volcanic/tectonic episodes typical of a fast spreading ridge. Further, the observations support a new model for the temporal evolution of episodic hydrothermal activity. Hydrothermal convection is unstable and superficial during the volcanic stage (dykes injection). At the beginning of the teaonic stage (graben formation) faults allow deep circulation and hot fluid to reach the surface. As the graben widens hydrothermal activity is less important and may cease. The heat of a new volcanic episode reactivates the deep hot water circulation along the graben faults completing a cycle.
69 nouveaux sites hydrothermaux ont été découverts entre 17'5 et 18'40'5 sur quatre segments présentant des activités volcaniques et tectoniques contrastées. A 17°10'S,17025'S et 18'37'5, la ride forme un dôme et l'activité volcanique est dominante. Les émissions hydrothermales sont d'abord diffuses et de basse température, puis focalisées et de haute température. A 18°15'S la majorité des sites hydrothermaux sont inactifs dans un graben axial dépourvu de laves récentes. A 18'32'5, des laves récentes s'épanchent au fond du graben. Les circuits hydrothermaux réactivés par le nouvel épisode volcanique se traduisent par des diffusions sur les laves récentes et par une reprise des émissions de haute température le long des murs du graben. Ces quatre segments traduisent des épisodes volcanoltectoniques successifs, caractéristiques de I'évolution temporelle des dorsales rapides. Les observations permettent de proposer un nouveau modèle de l'activité hydrothermale. Les circuits hydrothermaux sont diffus, peu structurés, instables et superficiels durant les épisodes volcaniques. Au début des épisodes tectoniques, les failles du graben drainent les fluides chauds en profondeur, puis lorsque le graben s'élargit, l'activité s'interrompt. La reprise de l'activité volcanique réamorce les circulations profondes le long des failles du graben.
Comptes Rendus de l'Academie des Sciences Serie II (1251-8069) (Gauthier-villars), 1994-12 , Vol. 319 , N. 11 , P. 1399-1406

Droits : Académie des Sciences
http://archimer.ifremer.fr/doc/00183/29455/27889.pdf
http://archimer.ifremer.fr/doc/00183/29455/

Éditeur(s) : Actes de colloques. Ifremer Brest [ACTES COLLOQ. IFREMER.]. 1986
Résumé : Seawater samples taken from shallow suspended particle maxima (20-57m) at or near the base of the surface mixed layer in various oceanic areas were tested for their potential to produce hydrogen (H sub(2)) gas. Results suggest that hydrogen can be bacterially produced through a fermentative process in microanaerobic niches within particulate matter. The organisms responsible for this process are ubiquitous within the temperate and tropical waters sampled. Enumeration of potential H sub(2)-producing bacteria using fluorescent antibody techniques yielded a maximum at the base of the surface mixed layer, the same depth where the greatest H sub(2) gas production potential was observed. Hydrogen-producing bacteria comprised up to 15% of the total bacterial direct count (AODC). Findings indicate that bacteria associated with shallow nepheloid layers are capable of producing gas and thus contributing to the observed supersaturated gas concentration in the marine environment.
Des échantillons d'eau de mer contenant des particules en suspension ont été prélevés en zone peu profonde (20 à 57 m) sur ou près de la couche brassée de surface en différents points de l'océan et ont été testés pour leur potentiel de production d'H2. Les résultats suggèrent que l'hydrogène peut être produit, par les bactéries, lors d'un processus fermentatif dans des microniches anaérobies de la matière particulaire. Les organismes responsables de ce processus sont ubiquistes dans les échantillons provenant des eaux tempérées el tropicales. Les numérations maximales de bactéries potentiellement productrices d'hydrocele, faites par des techniques d'anticorps fluorescents, sont obtenues à la base de la couche brassée de surface ; à cette même profondeur est observé le potentiel de production d'hydrogène le plus important. Les bactéries productrices d'hydrogène constituent jusqu'à 15 % des numérations bactériennes totales, effectuées par comptage direct (AODC). Ces observations indiquent que les bactéries associées aux couches nephéloïdes peu profondes sont capables de produire de l'hydrogène et contribuent ainsi à la sursaturation en gaz observée dans le milieu marin.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1984/acte-962.pdf
http://archimer.ifremer.fr/doc/00000/962/

Éditeur(s) : HAL CCSD American Meteorological Society
Résumé : Global positioning system (GPS) data from a dense network have been used for the analysis of the diurnal cycle of water vapor over Marseille, France, during the second intensive observation period (IOP2; 21–26 June 2001) of the Expérience sur Sites pour Contraindre les Modèles de Pollution Atmosphérique et de Transport d'Emission (ESCOMPTE) field experiment. Both tomographic analyses and integrated water vapor (IWV) contents from GPS have been used, in addition to wind profiler data and surface observations. Tomographic analysis of data from the dense GPS network and radiosondes provided the continuous temporal evolution of the vertical distribution of water vapor over the city of Marseille. The city is located on the shore of the Mediterranean Sea in southeastern France and is often under the influence of sea-breeze effects. Two different layers of breeze circulation are identified: a shallow sea breeze, blowing perpendicular to the local coastline, and a deep sea breeze, induced by the regional temperature gradient between sea and land. The origin of water vapor is shown to be mainly due to the advection of marine moist air by these sea-breeze circulations. However, the diurnal cycle of water vapor over Marseille is strongly influenced by the synoptic situation, which changes during the IOP2 (between a northerly mistral in the early stage of the IOP and an easterly wind at the end). It is shown that vertical profiles from tomographic analyses (combined with wind profiler data) allow for a proper interpretation of the diurnal cycle observed in IWV. Two-dimensional maps of IWV are also shown to complement the description of the horizontal advection of moisture by the different circulation regimes.
ISSN: 1558-8424

hal-00273624
https://hal.archives-ouvertes.fr/hal-00273624
https://hal.archives-ouvertes.fr/hal-00273624/document
https://hal.archives-ouvertes.fr/hal-00273624/file/drJAM_cycle_diurne_GPS_rev1.pdf
DOI : 10.1175/JAM2450.1

Éditeur(s) : Blackwell science
Résumé : This paper provides an exploratory analysis aiming to seek whether the colour of environmental noise theory could help in understanding the intriguing reproductive strategy of Atlantic bluefin tuna (BFT). A frequency-based approach based on spectral exponents, f(beta) with beta < 0, is chosen and applied on 10 biogeographical provinces covering the North Atlantic. The major BFT spawning area, i.e. the Mediterranean Sea, was the only one to display a pink power spectrum, whereas open ocean regions displayed more reddened fluctuations, i.e. greater variance at low frequencies. Environmental noise in the Mediterranean could, thus, offer more favourable characteristics on the long-term than the open ocean. The implications of these findings are discussed in regards to medium and long (possibly evolutionary) time scales.
Fisheries Oceanography (1054-6006) (Blackwell science), 2007-03 , Vol. 16 , N. 2 , P. 202-206

Droits : 2007 Blackwell science
http://archimer.ifremer.fr/doc/2007/publication-2437.pdf
DOI:10.1111/j.1365-2419.2006.00424.x
http://archimer.ifremer.fr/doc/00000/2437/

Éditeur(s) : Université Paris 7 – Denis Diderot
Résumé : Sea surface salinity (SSS) influences numerous oceanic phenomena, for instance surface water ventilation, deep water formation and thermohaline circulation. SSS also controls some ocean-atmosphere coupled processes, such as the intensity of freshwater flux and the penetration of heat flux and turbulence. Salinity is more difficult to measure than temperature from in situ surveys, which results in 20 times less data being currently available. Moreover, sea surface temperature (SST) is routinely estimated from satellites, which is not possible yet for SSS. Two space missions will fill this gap soon: SMOS from the European Space Agency and Aquarius/SAC-D from NASA and CONAE. To contribute to the SMOS project, we propose a method for estimating SSS from current satellite observations and for studying the mechanisms governing its variability. We developed a simplified model of the ocean mixed layer, based on the "slab mixed layer" formulation (Frankignoul et Hasselmann, 1977). This 2D horizontal model is implemented over the global ocean, using a near 100 km resolution, and integrated during a climatological year. Air-sea fluxes are taken from the ECMWF meteorological model (ERA40 reanalysis) and the surface currents are provided by altimeter data (SSALTO-DUACS analysis). The mixed layer depth (MLD) is derived from SST observations, using an original inversion technique. The MLD fields obtained from this inversion are well correlated to in situ estimates. This effective depth represents the air-sea fluxes penetration and ensures consistency between fluxes, les currents and SST. We first validate the simulation through examination of the heat balance in north-eastern Atlantic, by comparing to measurements and models from the POMME experiment. Then we study the salinity balance in the global domain, in terms of its geographical distribution and seasonal evolution. Equilibrium between the various processes appears generally more complex than for temperature. Noteworthy, the role of atmospheric flux is less predominant (22%), while geostrophic advection (33%) and diapycnal mixing (22%) contribute more strongly. Our results indicate this model succeeds in reconstructing SSS variability over most of the oceans. Daily SSS variations are also simulated, whereas they are not represented in current observed data at a global scale. Owing to its simplicity and fast computation, the model will be useful to the SMOS mission. It can help for the measurement calibration/validation and provide a first guess estimate to the sophisticated algorithm required for SSS restitution.
La salinité de surface des océans (SSS) influence de nombreux phénomènes océaniques, parmi lesquels la ventilation des eaux de surface, la formation d'eaux profondes et la circulation thermohaline. Elle détermine aussi certains processus couplés océan-atmosphère, notamment l'intensité du flux d'eau douce, la pénétration du flux de chaleur et de la turbulence. La mesure in situ de salinité est plus compliquée que celle de température, si bien qu'on dispose actuellement de 20 fois moins de données pour cette propriété. De plus, la température de surface (SST) est couramment estimée par satellite, ce qui n'est pas encore le cas de la SSS. Deux missions spatiales vont prochainement combler cette lacune : le satellite SMOS de l'Agence Spatiale Européenne et le satellite Aquarius/SAC-D de la NASA et de la CONAE. En préparation du projet SMOS, nous proposons une méthode pour estimer la SSS à partir des observations satellitaires actuelles et étudier les mécanismes de sa variabilité. Nous avons développé un modèle simplifié de couche mélangée océanique, basé sur la formulation "slab mixed layer" (Frankignoul et Hasselmann, 1977). Ce modèle 2D horizontal est implémenté sur l'océan global, avec une résolution proche de 100 km, et intégré au cours d'une année climatologique. Les flux air-mer proviennent du modèle météorologique ECMWF (réanalyse ERA40) et les courants de surface sont issus de l'altimétrie (analyse SSALTO-DUACS). La profondeur de la couche mélangée (MLD) est dérivée des observations de SST, grâce à une technique d'inversion originale. La MLD obtenue par inversion est bien corrélée aux estimations basées sur des données in situ. Cette profondeur effective représente la pénétration des flux air-mer et assure la cohérence entre les flux, les courants et la SST. La simulation est d'abord validée en examinant le bilan de chaleur dans l'Atlantique Nord-Est, par comparaison aux mesures et aux modèles de l'expérience POMME. Puis le bilan de salinité est étudié dans le domaine global, en termes de distribution géographique et d'évolution saisonnière. L'équilibre entre les différents processus est généralement plus complexe que pour la température. Notamment, le rôle du flux atmosphérique est moins prépondérant (22%), tandis que l'advection géostrophique (33%) et le mélange diapycnal (22%) contribuent fortement. Nos résultats montrent que ce modèle parvient à restituer la variabilité de la SSS sur la majeure partie des océans. Le modèle simule aussi les variations journalières de SSS, qui ne sont pas représentées à l'échelle globale dans les observations actuelles. Grâce à sa simplicité et à sa rapidité, le modèle pourra être utile dans le cadre de SMOS. Il pourra aider à la calibration/validation de la mesure et fournir une estimation a priori pour l'algorithme complexe nécessaire à la restitution de la SSS.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/these-2302.pdf
http://archimer.ifremer.fr/doc/00000/2302/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
High sea surface temperature accompanied by high levels of solar irradiance is responsible for the disruption of the symbiosis between cnidarians and their symbiotic dinoflagellates from the genus Symbiodinium. This phenomenon, known as coral bleaching, is one of the major threats affecting coral reefs around the world. Because an important molecular trigger to bleaching appears related to the production of reactive oxygen species (ROS), it is critical to understand the function of the antioxidant network of Symbiodinium species. In this study we investigated the response of two Symbiodinium species, from contrasting environments, to a chemically induced oxidative stress. ROS produced during this oxidative burst reduced photosynthesis by 30 to 50% and significantly decreased the activity of superoxide dismutase. Lipid peroxidation levels and carotenoid concentrations, especially diatoxanthin, confirm that these molecules act as antioxidants and contribute to the stabilization of membrane lipids. The comparative analysis between the two Symbiodinium species allowed us to highlight that Symbiodinium sp. clade A temperate was more tolerant to oxidative stress than the tropical S. kawagutii clade F. These differences are very likely a consequence of adaptation to their natural environment, with the temperate species experiencing conditions of temperature and irradiance much more variable and extreme.
ISSN: 0140-7791

hal-01546161
https://hal.archives-ouvertes.fr/hal-01546161
DOI : 10.1111/pce.12825

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Coral bleaching events threaten coral reef habitats globally and cause severe declines of local biodiversity and productivity.Related to high sea surface temperatures (SST), bleaching events are expected to increase as a consequenceof future global warming. However, response to climate change is still uncertain as future low-latitude climatic conditionshave no present-day analogue. Sea surface temperatures during the Eocene epoch were warmer than forecastedchanges for the coming century, and distributions of corals during the Eocene may help to inform models forecastingthe future of coral reefs. We coupled contemporary and Eocene coral occurrences with information on their respectiveclimatic conditions to model the thermal niche of coral reefs and its potential response to projected climate change.We found that under the RCP8.5 climate change scenario, the global suitability for coral reefs may increase up to 16%by 2100, mostly due to improved suitability of higher latitudes. In contrast, in its current range, coral reef suitabilitymay decrease up to 46% by 2100. Reduction in thermal suitability will be most severe in biodiversity hotspots, especiallyin the Indo-Australian Archipelago. Our results suggest that many contemporary hotspots for coral reefs,including those that have been refugia in the past, spatially mismatch with future suitable areas for coral reefs posingchallenges to conservation actions under climate change.
ISSN: 1354-1013

hal-01145464
https://hal.archives-ouvertes.fr/hal-01145464
DOI : 10.1111/gcb.12868

Éditeur(s) : Amer Geophysical Union
Résumé : Bolide impacts and large-scale volcanic eruptions have been proposed as possible causes of the massive extinction of life that has occurred episodically in Earth's history. In spite of the catastrophic disruption of the local environment that accompanies bolide impacts and volcanic eruptions, it has been difficult to explain why these events sometimes lead to global extinction of species. We propose that, in some cases, the missing link may be provided by hypercanes, runaway hurricanes that are capable of injecting massive amounts of water and aerosols into the middle and upper stratosphere, where they may have profound effects on atmospheric chemistry and radiative transfer. Hypercanes are theorized to occur when the sea surface temperature exceeds a critical threshold, which may occur when sea water is locally heated by bolide impact, shallow-sea volcanism, or possibly, by overturning of superheated brine pools formed by underwater volcanic activity. Simulations using a convection-resolving nonhydrostatic, axisymmetric numerical model show that hypercanes can indeed develop when the sea surface temperature is high, and that they inject large amounts of mass into the stratosphere.
Journal Of Geophysical Research-atmospheres (2169-897X) (Amer Geophysical Union), 1995-07 , Vol. 100 , N. D7 , P. 13755-13765

Droits : 1995 by the American Geophysical Union.
http://archimer.ifremer.fr/doc/00258/36966/35611.pdf
DOI:10.1029/95JD01368
http://archimer.ifremer.fr/doc/00258/36966/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Factors controlling ocean acidification and its temporal variations were studied over the 1995–2011 period at the Dyfamed site at 10 m depth, in the North Mediterranean Sea. The results indicated a mean annual decrease of 0.003 ± 0.001 pH units on the seawater scale. The seasonal variability was characterized by a pH decrease during springtime and a strong pH increase in late fall. Anthropogenic CO2 (CANT) absorption by the ocean was the key driver of seawater acidification in this region, accounting for about 70% of the observed drop in pH, followed by water temperature (about 30%). The total inorganic carbon (CT) data showed a CT increase of 30.0 ± 1.0 μmol kg−1 per decade. This decadal increase is mainly due to the CANT penetration (43.2 μmol kg−1 per decade) in surface waters, which is mitigated for by relatively small opposing changes in CT due to physical and biological processes.
ISSN: 0141-1136

hal-01286093
https://hal-univ-perp.archives-ouvertes.fr/hal-01286093
DOI : 10.1016/j.marenvres.2016.02.016

Éditeur(s) : HAL CCSD Integrated Ocean Drilling Program
Résumé : Integrated Ocean Drilling Program (IODP) Expedition 325, designed to investigate the fossil reefs on the shelf edge of the Great Barrier Reef, was the fourth expedition to utilize a mission-specific platform and was conducted by the European Consortium for Ocean Research Drilling (ECORD) Science Operator (ESO). The objectives of Expedition 325 were to establish the course of sea level change, define sea-surface temperature variations, and analyze the impact of these environmental changes on reef growth and geometry for the region over the period of 20-10 ka. To meet these objectives, a succession of fossil reef structures preserved on the shelf edge seaward of the modern barrier reef were cored from a dynamically positioned vessel in February-April 2010. A total of 34 boreholes across 17 sites were cored in depths ranging from 42.27 to 167.14 meters below sea level (lowest astronomical tide taken from corrected EM300 multibeam bathymetry data). Borehole logging operations in four boreholes provided continuous geophysical information about the drilled strata. The cores were described during the Onshore Science Party (OSP) at the IODP Bremen Core Repository (Germany) in July 2010, where minimum and some standard measurements were made. Preliminary postcruise dating of core catcher samples and initial observations of the cores made during the OSP confirm that coral reef material ranging in age from >30,000 to 9,000 calendar years before present (years before 1950 AD) was recovered during Expedition 325. Further postcruise research on samples taken during the OSP is expected to fulfill the objectives of the expedition.
ISSN: 1930-1014

hal-00855800
https://hal.archives-ouvertes.fr/hal-00855800

Éditeur(s) : Gauthier-Villars
Résumé : Data collected in an area enclosing New Caledonia are analysed both for the open ocean (17 degrees S-27 degrees S, 169 degrees E-170 degrees E; 1972-1992) and for one point in its lagoon (1967-1993), in order to improve our knowledge of the regional environment, with emphasis on seasonal and interannual (i.e. ENSO) variability. Long-term means and seasonal changes in surface wind, sea-surface temperature and salinity, and 0-400 m temperature, salinity and zonal geostrophic current are first described to Set the context. Through comparisons with the Southern Oscillation Index (SOI), it is demonstrated that there are signals in these parameters that are connected with ENSO. During the warm phase of ENSO (SOI < 0, El Nino), we observed saltier-than-average anomalies in sea-surface salinity (similar to 0.2), 0-50 m cold temperature anomalies (similar to 0.5 degrees C) contrasting with the well-known warm eastern equatorial Pacific anomalies, together with westerly (similar to 10 m(2) s(-2)) and southerly (similar to 4 m(2) s-2) wind anomalies over a large part of the studied area. Conversely, anomalies of similar magnitude but of opposite sign were detected during the cold phase of ENSO (SOI > 0; La Nina). The mechanisms which connect these regional anomalies to ENSO evolution at low-latitudes are qualitatively discussed.
Oceanolica Acta (0399-1784) (Gauthier-Villars), 1997 , Vol. 20 , N. 3 , P. 481-491

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00093/20410/18077.pdf
http://archimer.ifremer.fr/doc/00093/20410/

Résumé : Ocean Thermal Energy Conversion, OTEC, is a concentrated renewable source of energy available in the one third of the world's ocean lying in the tropics. An OTEC plant is a heat engine fed with warm surface water and cold water pumped up from the deep. The difference of temperature, 20°C, is small, it can be used to produce electricity as well as fresh water. Plants can be installed on land or at sea. The main problem is to build and deploy a large diameter pipe to pump the cold water from 600 to 1 000 m in depth. France, who discovered the idea realised some major demonstrations fifty years ago. More recently US and Japanese firms have spent more than dollars 200 millions to develop prototypes and research in this field. Several major OTEC pilot plants are presently discussed mainly hy US, Japanese and French teams. The main challenge is to prove the potential competitivness of OTEC electricity in the 10 to 100 MWe range, with diesel electricity in the 1990's. Production of OTEC desalination water and marine proteins are also under consideration. The present book give a unique overview of both technical and economical aspects of this promising source of energy. [NOT CONTROLLED OCR]
L'Océan présente un potentiel considérable d'énergie renouvelable. Dans ce domaine, l'énergie thermique des mers (ETM) apparaît très riche de promesses. C'est une idée française: elle est due à d'Arsonval (1881). Les travaux de G. Claude et P. Boucherat (1928-1934), les projets d'Abidjan (1940-1956) et de la Guadeloupe (1958) essaieront de la matérialiser. Depuis les années 60, ce sont surtout les Américains et les Japonais qui développent les recherches. La France a repris ses projets à partir de 1978, de même que certains pays d'Europe, Cet ouvrage expose les caractéristiques de l'ETM et fixe les ordres de grandeur qui permettent de dimensionner les composants d'une centrale. Il rend compte des recherches menées dans différents pays pour maîtriser la technologie ETM :aux États-Unis, au Japon, en Grande-Bretagne, en Suède, en France et, plus récemment, en Inde ou à Taïwan. Il examine les potentialités réelles dans 98 pays et territoires qui ont accès au gisement ETM et dont les 2/3 sont dans la mouvance européenne. L'étude traite enfin du coût de cette énergie dans la perspective d'une compétitivité du KWG/ETM avec le KWG/fioul. L'examen porte ainsi sur d'autres actions possibles: production eau douce, aquaculture, froid. [OCR NON CONTRÔLE]

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1986/rapport-4310.pdf
http://archimer.ifremer.fr/doc/00000/4310/

Éditeur(s) : Springer
Résumé : While it is well known that the ocean is one of the most important component of the climate system, with a heat capacity 1,100 times greater than the atmosphere, the ocean is also the primary reservoir for freshwater transport to the atmosphere and largest component of the global water cycle. Two new satellite sensors, the ESA Soil Moisture and Ocean Salinity (SMOS) and the NASA Aquarius SAC-D missions, are now providing the first space-borne measurements of the sea surface salinity (SSS). In this paper, we present examples demonstrating how SMOS-derived SSS data are being used to better characterize key land–ocean and atmosphere–ocean interaction processes that occur within the marine hydrological cycle. In particular, SMOS with its ocean mapping capability provides observations across the world’s largest tropical ocean fresh pool regions, and we discuss from intraseasonal to interannual precipitation impacts as well as large-scale river runoff from the Amazon–Orinoco and Congo rivers and its offshore advection. Synergistic multi-satellite analyses of these new surface salinity data sets combined with sea surface temperature, dynamical height and currents from altimetry, surface wind, ocean color, rainfall estimates, and in situ observations are shown to yield new freshwater budget insight. Finally, SSS observations from the SMOS and Aquarius/SAC-D sensors are combined to examine the response of the upper ocean to tropical cyclone passage including the potential role that a freshwater-induced upper ocean barrier layer may play in modulating surface cooling and enthalpy flux in tropical cyclone track regions.
Surveys In Geophysics (0169-3298) (Springer), 2014-05 , Vol. 35 , N. 3 , P. 681-722

Droits : Springer Science+Business Media Dordrecht 2013
http://archimer.ifremer.fr/doc/00152/26334/24430.pdf
DOI:10.1007/s10712-013-9244-0
http://archimer.ifremer.fr/doc/00152/26334/

Éditeur(s) : Taylor & Francis Ltd
Résumé : A new method is developed to estimate daily turbulent airsea fluxes over the global ocean on a 0.25 degrees grid. The required surface wind speed (w(10)) and specific air humidity (q(10)) at 10m height are both estimated from remotely sensed measurements. w(10) is obtained from the SeaWinds scatterometer on board the QuikSCAT satellite. A new empirical model relating brightness temperatures (T-b) from the Special Sensor Microwave Imager (SSM/I) and q(10) is developed. It is an extension of the author's previous q(10) model. In addition to T-b, the empirical model includes sea surface temperature (SST) and airsea temperature difference data. The calibration of the new empirical q(10) model utilizes q(10) from the latest version of the National Oceanography Centre airsea interaction gridded data set (NOCS2.0). Compared with mooring data, the new satellite q(10) exhibits better statistical results than previous estimates. For instance, the bias, the root mean square (RMS), and the correlation coefficient values estimated from comparisons between satellite and moorings in the northeast Atlantic and the Mediterranean Sea are 0.04gkg(1), 0.87gkg(1), and 0.95, respectively. The new satellite q(10) is used in combination with the newly reprocessed QuikSCAT V3, the latest version of SST analyses provided by the National Climatic Data Center (NCDC), and 10m air temperature estimated from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses (ERA-Interim), to determine three daily gridded turbulent quantities at 0.25 degrees spatial resolution: surface wind stress, latent heat flux (LHF), and sensible heat flux (SHF). Validation of the resulting fields is performed through a comprehensive comparison with daily, in situ values of LHF and SHF from buoys. In the northeast Atlantic basin, the satellite-derived daily LHF has bias, RMS, and correlation of 5Wm(2), 27Wm(2), and 0.89, respectively. For SHF, the statistical parameters are 2Wm(2), 10Wm(2), and 0.94, respectively. At global scale, the new satellite LHF and SHF are compared to NOCS2.0 daily estimates. Both daily fluxes exhibit similar spatial and seasonal variability. The main departures are found at latitudes south of 40 degrees S, where satellite latent and sensible heat fluxes are generally larger.
International Journal Of Remote Sensing (0143-1161) (Taylor & Francis Ltd), 2013-07 , Vol. 34 , N. 14 , P. 5243-5261

Droits : 2013 Taylor & Francis
http://archimer.ifremer.fr/doc/00137/24825/23575.pdf
DOI:10.1080/01431161.2013.787502
http://archimer.ifremer.fr/doc/00137/24825/