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Registros recuperados: 23
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A 6 year record of baroclinic transport variability of the Antarctic Circumpolar Current at 140 degrees E derived from expendable bathythermograph and altimeter measurements ArchiMer
Rintoul, Sr; Sokolov, S; Church, J.
Repeat hydrographic sections across the Antarctic Circumpolar Current are used to derive an empirical relationship between upper ocean temperature and the baroclinic transport stream function. Cross validation shows this relationship can be used to infer baroclinic transport (above and relative to 2500 dbar) from temperature measurements with an error of a few per cent. The mean transport distribution derived from 31 austral summer expendable bathythermograph (XBT) sections over a 6 year period consists of westward flow immediately south of Tasmania, a broad band of strong eastward flow between 50degrees and 55degreesS, and three cores of eastward flow south of 55degreesS. By defining a second empirical relationship between surface dynamic height and...
Tipo: Text Palavras-chave: Baroclinic transport; Antarctic Circumpolar Current; Interannual variability; Satellite altimeter; XBT.
Ano: 2002 URL: https://archimer.ifremer.fr/doc/00223/33444/31832.pdf
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A model of the general circulation in the Persian Gulf and in the Strait of Hormuz: Intraseasonal to interannual variability ArchiMer
Pous, Stephane; Lazure, Pascal; Carton, Xavier.
Previous studies modeling the circulation and thermohaline structure in the Persian Gulf have suggested that interannual variability and vertical mixing processes could explain the model biases when compared to the few observations available. Here, a realistic, interannual, high-resolution model of the Persian Gulf is presented, validated against observations and then used to describe the intraseasonal to interannual variability in the circulation, water mass formation and exchange through the Strait of Hormuz. Sensitivity experiments to model settings, in particular vertical mixing parameterizations, have been performed in order to have the best comparison with all available observations. Main circulation and water mass characteristics correspond well to...
Tipo: Text Palavras-chave: Persian Gulf; Strait of Hormuz; Numerical model; Hydrology; Currents; Interannual variability.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00244/35563/35324.pdf
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A multi-decadal hindcast of a physical–biogeochemical model and derived oceanographic indices in the Bay of Biscay ArchiMer
Huret, Martin; Sourisseau, Marc; Petitgas, Pierre; Struski, Caroline; Leger, Fabien; Lazure, Pascal.
Multiple year oceanographic simulations (hindcast) are identified as a priority oceanography product for fisheries and environment studies since they provide a unique continuous long-term dataset allowing integrated assessment of the ocean state and evolution. We performed a 37 year (1972–2008) hindcast run with a coupled physical–biogeochemical model in the Bay of Biscay. The coupled model and the hindcast configuration are described. A model skill assessment is performed with a large set of in-situ data. Average seasonal currents show major circulation patterns over the shelf. Among tracers, temperature and salinity have the best agreement, ahead of nitrates and silicates, chlorophyll, and finally phosphates and ammonium. For chlorophyll, improved...
Tipo: Text Palavras-chave: Physical-biogeochemical model; Hindcast; Skill assessment; Environmental indices; Seasonal pattern; Interannual variability; Fisheries oceanography; Bay of Biscay.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00114/22538/20237.pdf
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Arctic Ocean freshwater content and its decadal memory of sea-level pressure ArchiMer
Johnson, Helen L.; Cornish, Sam B.; Kostov, Yavor; Beer, Emma; Lique, Camille.
Arctic freshwater content (FWC) has increased significantly over the last two decades, with potential future implications for the Atlantic meridional overturning circulation downstream. We investigate the relationship between Arctic FWC and atmospheric circulation in the control run of a coupled climate model. Multiple linear lagged regression is used to extract the response of total Arctic FWC to a hypothetical step increase in the principal components of sea‐level pressure. The results demonstrate that the FWC adjusts on a decadal timescale, consistent with the idea that wind‐driven ocean dynamics and eddies determine the response of Arctic Ocean circulation and properties to a change in surface forcing, as suggested by idealized models and theory....
Tipo: Text Palavras-chave: Arctic Ocean; Climate change; Interannual variability; Freshwater; Adjustment timescales; Ocean dynamics.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00440/55117/56571.pdf
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Atlas Hydrologique des eaux superficielles du plateau continental mauritanien OceanDocs
Dobrovine, B.; Mahfoudh, M.; Ould Dedah, S..
Ce volume du Bulletin Scientifique est entièrement consacré à l'atlas hydrologique des eaux superficielles du plateau continental mauritanien
Tipo: Journal Contribution Palavras-chave: Eaux de surface; Interannual variability; Amplitude saisonnière; Waters surface; Evolution saisonnière; Ecarts de température; Moyenne mensuelle; Moyenne saisonnière; Continental shelf; Mauritanie; Températures; Variations in temperature; Temperatures; Plateu continental; Mean seasonal range of temperature; Variabilité interannuelle; Mean Annual temperatures; Mauritania; Seasonal evolution; Températures moyennes annuelles; Oceanographic atlases; Hydrology.
Ano: 1990 URL: http://hdl.handle.net/1834/766
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Characterizing, modelling and understanding the climate variability of the deep water formation in the North-Western Mediterranean Sea ArchiMer
Somot, Samuel; Houpert, Loic; Sevault, Florence; Testor, Pierre; Bosse, Anthony; Taupier-letage, Isabelle; Bouin, Marie-noelle; Waldman, Robin; Cassou, Christophe; Sanchez-gomez, Emilia; Durrieu De Madron, Xavier; Adloff, Fanny; Nabat, Pierre; Herrmann, Marine.
Observing, modelling and understanding the climate-scale variability of the deep water formation (DWF) in the North-Western Mediterranean Sea remains today very challenging. In this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. These quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980–2013 and a detailed multi-indicator description of the period 2007–2013. Then a 1980–2013 hindcast simulation is performed with a fully-coupled regional climate system model including the high-resolution representation of the regional atmosphere, ocean, land-surface and rivers. The simulation reproduces...
Tipo: Text Palavras-chave: Deep water formation; Open-sea deep convection; Interannual variability; Mediterranean Sea; Regional climate models; Climate trends.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00348/45948/45654.pdf
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Controls on circulation, cross-shelf exchange, and dense water formation in an Antarctic polynya ArchiMer
Snow, K.; Sloyan, B. M.; Rintoul, S. R.; Hogg, A. Mcc.; Downes, S. M..
Circulation on the Antarctic continental shelf influences cross-shelf exchange, Antarctic Bottom Water formation, and ocean heat flux to floating ice shelves. The physical processes driving the shelf circulation and its seasonal and interannual variability remain poorly understood. We use a unique time series of repeat hydrographic observations from the Adélie Land continental shelf and a box inverse model to explore the relationship between surface forcing, shelf circulation, cross-shelf exchange, and dense water formation. A wind-driven northwestward coastal current, set up by onshore Ekman transport, dominates the summer circulation. During winter, strong buoyancy loss creates dense shelf water. This dense water flows off the shelf, with a compensating...
Tipo: Text Palavras-chave: Antarctic shelf circulation; Cross-shelf exchange; Antarctic bottom water; Surface fluxes; Seasonal; Interannual variability.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00344/45566/45173.pdf
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Evidence of atmosphere-sea ice-ocean coupling in the Terra Nova Bay polynya (Ross Sea-Antarctica) ArchiMer
Rusciano, Emanuela; Budillon, Giorgio; Fusco, Giannetta; Spezie, Giancarlo.
A rare long time series of hydrographic profiles and moored current meter data, collected from 1995 to 2008 in Terra Nova Bay polynya, are used in combination with meteorological data, acquired by an Automatic Weather Station, and remote sensing data from a Special Sensor Microwave/Imager. The behaviour of Terra Nova Bay coastal polynya in terms of air ice sea interactions and the consequent High Salinity Shelf Water production are detailed. The katabatic regime that characterizes Terra Nova Bay polynya is investigated and different types of events are distinguished on the bases of their duration and intensity. The more frequent katabatic events take place during the winter season from April to October, blowing on average 1-7 h, with speed between 25 and...
Tipo: Text Palavras-chave: Terra Nova Bay polynya; High Salinity Shelf Water; Interannual variability; Katabatic wind; Air-sea-ice interaction.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00149/26041/24165.pdf
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Global Air-Sea CO2 Flux in 22 CMIP5 Models: Multiyear Mean and Interannual Variability* ArchiMer
Dong, Fang; Li, Yangchun; Wang, Bin; Huang, Wenyu; Shi, Yanyan; Dong, Wenhao.
To assess the capability of the latest Earth system models (ESMs) in representing historical global air-sea CO2 flux, 22 models from phase 5 of the Coupled Model Intercomparision Project (CMIP5) are analyzed, with a focus on the spatial distribution of multiyear mean and interannual variability. Results show that the global distribution of air-sea CO2 flux is reasonable in most of the models and that the main differences between models and observationally based results exist in regions with strong vertical movement. The annual mean flux in the 18-member multimodel ensemble (MME; four models were excluded because of their poor performances) mean during 1996-2004 is 1.95 Pg C yr(-1) (1 Pg = 10(15) g; positive values mean into the ocean), and all but one...
Tipo: Text Palavras-chave: Interannual variability; Model output statistics; Model comparison; Variability; Models and modeling; Ocean models; Ensembles; Climate models.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00383/49421/49858.pdf
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Interannual variability of the Mediterranean outflow observed in Espartel sill, western Strait of Gibraltar ArchiMer
Garcia-lafuente, J.; Delgado, J.; Sanchez Roman, A.; Soto, J.; Carracedo, Lidia; Diaz Del Rio, G..
Four-year time series of observations in Espartel sill at the western part of the Strait of Gibraltar have been analyzed in order to investigate the variability of the Mediterranean outflow. It is assumed that the observed variability comes from the changing properties of the dense waters that are located at the maximum depth from where they can be uplifted in the upstream basin (Alboran Sea, inside the Mediterranean Sea) and evacuated through the strait. From this perspective, the following three mechanisms are investigated: (1) the replenishment of the deep basin by newly formed Western Mediterranean Deep Water that, depending on its density, can either uplift old resident waters or lay above them leaving in any case a cold signature in the temperature...
Tipo: Text Palavras-chave: Mediterranean outflow; Alboran Sea gyres; Interannual variability; Strait of Gibraltar; Seasonality; WMDW.
Ano: 2009 URL: https://archimer.ifremer.fr/doc/00629/74113/73544.pdf
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Interannual variability of the Tropical Indian Ocean mixed layer depth ArchiMer
Keerthi, M. G.; Lengaigne, M.; Vialard, Jerome; De Boyer Montegut, Clement; Muraleedharan, P. M..
In the present study, interannual fluctuations of the mixed layer depth (MLD) in the tropical Indian Ocean are investigated from a long-term (1960-2007) eddy permitting numerical simulation and a new observational dataset built from hydrographic in situ data including Argo data (1969-2008). Both datasets show similar interannual variability patterns in relation with known climate modes and reasonable phase agreement in key regions. Due to the scarcity of the observational dataset, we then largely rely on the model to describe the interannual MLD variations in more detail. MLD interannual variability is two to four times smaller than the seasonal cycle. A large fraction of MLD interannual variations is linked to large-scale climate modes, with the exception...
Tipo: Text Palavras-chave: Mixed layer; Interannual variability; Indian Ocean; Indian Ocean Dipole; El Nino/Southern Oscillation; Monsoon.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00124/23564/22771.pdf
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Interannual variability of upper ocean water masses as inferred from Argo Array ArchiMer
Kolodziejczyk, Nicolas; Llovel, William; Portela, Esther.
nterannual variability of Ocean Heat Content (OHC) is intimately linked to ocean water mass changes. Water mass characteristics are imprinted at the ocean surface and are modulated by climate variability on interannual to decadal time scales. In this study, we investigate the water mass change and their variability using an isopycnal decomposition of the OHC. For that purpose, we address the thickness and temperature changes of these water masses using both individual temperature‐salinity profiles and optimal interpolated products from Argo data. Isopycnal decomposition allows us to characterize the water masses interannual variability and decadal trends of volume and OHC. During the last decade (2006–2015), much of interannual and decadal warming is...
Tipo: Text Palavras-chave: Water masses; Ocean heat content; Interannual variability; Argo; Mode water; Atmospheric forcing.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00510/62128/66340.pdf
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Interpretation of interannual variability in long-term aquatic ecological surveys ArchiMer
Cauvy-fraunié, Sophie; Trenkel, Verena; Daufresne, Martin; Maire, Anthony; Capra, Hervé; Olivier, Jean-michel; Lobry, Jérémy; Cazelles, Bernard; Lamouroux, Nicolas.
Long-term ecological surveys (LTES) often exhibit strong variability among sampling dates. The use and interpretation of such interannual variability is challenging due to the combination of multiple processes involved and sampling uncertainty. Here, we analysed the interannual variability in ~30 years of 150 species-density (fish and invertebrate) and environmental-observation time series in four aquatic-systems (stream, river, estuary, and marine continental shelf) with different sampling efforts to identify the information provided by this variability. We tested, using two empirical methods, whether we could observe simultaneous fluctuation between detrended time series corresponding to widely acknowledged assumptions about aquatic population dynamics:...
Tipo: Text Palavras-chave: Long-term ecological surveys (LTES); Aquatic species (stream -river-estuary- marine); Interannual variability; Symbolic analyses; Sampling efficiency.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00606/71805/70293.pdf
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Intraseasonal variability of equatorial Indian Ocean zonal currents ArchiMer
Sengupta, Debasis; Senan, Retish; Goswami, B. N.; Vialard, Jerome.
New satellite and in situ observations show large intraseasonal (10-60 day) variability of surface winds and upper- ocean current in the equatorial Indian Ocean, particularly in the east. An ocean model forced by the Quick Scatterometer (QuikSCAT) wind stress is used to study the dynamics of the intraseasonal zonal current. The model has realistic upper- ocean currents and thermocline depth variabilities on intraseasonal to interannual scales. The quality of the simulation is directly attributed to the accuracy of the wind forcing. At the equator, moderate westerly winds are punctuated by strong 10-40-day westerly wind bursts. The wind bursts force swift, intraseasonal (20-50 day) eastward equatorial jets in spring, summer, and fall. The zonal momentum...
Tipo: Text Palavras-chave: Sea surface temperature; Interannual variability; Dynamics; Circulation; Pacific; Model; Winds; Thermodynamics; Oscillation; Transports.
Ano: 2007 URL: https://archimer.ifremer.fr/doc/00203/31421/29820.pdf
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Modeled mixed-layer salinity balance in the Gulf of Guinea: seasonal and interannual variability ArchiMer
Da-allada, Casimir Yelognisse; Du Penhoat, Yves; Jouanno, Julien; Alory, Gael; Hounkonnou, Norbert Mahouton.
A regional numerical simulation and observations were used to investigate the various processes controlling mixed-layer salinity balance on seasonal and interannual time scales in the Gulf of Guinea. Processes were quantified using a mixed-layer salt budget. Model results correctly reproduced the mean, phase, and amplitude of observed seasonal near-surface salinity. The results indicated that on seasonal time scales, the mixed-layer salinity balance differed from one region to another. The surface salinity seasonal cycle was characterized by strong salinization during May for coastal areas north and south of the equator. Model results suggested that vertical mixing controls the mixed-layer salinity increase at the equator during May, while both vertical...
Tipo: Text Palavras-chave: Sea surface salinity; Gulf of guinea; Model; Mixed-layer budget; Seasonal variability; Interannual variability.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00242/35333/36310.pdf
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RAMA The Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction ArchiMer
Mcphaden, M. J.; Meyers, G.; Ando, K.; Masumoto, Y.; Murty, V. S. N.; Ravichandran, M.; Syamsudin, F.; Vialard, Jerome; Yu, L.; Yu, W..
The Indian Ocean is unique among the three tropical ocean basins in that it is blocked at 25 degrees N by the Asian landmass. Seasonal heating and cooling of the land sets the stage for dramatic monsoon wind reversals, strong ocean atmosphere interactions, and intense seasonal rains over the Indian subcontinent, Southeast Asia, East Africa, and Australia. Recurrence of these monsoon rains is critical to agricultural production that supports a third of the world's population. The Indian Ocean also remotely influences the evolution of El Nino-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), North American weather, and hurricane activity. Despite its importance in the regional and global climate system though, the Indian Ocean is the most...
Tipo: Text Palavras-chave: Madden julian oscillation; Tropical indian ocean; Sea heat fluxes; Intraseasonal variability; Equatorial currents; Summer monsoon; Interannual variability; Arabian sea; El nino; Rainfall variability.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00185/29632/27992.pdf
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Seasonal and inter-annual variability of bacterioplankton biomass at station Kerfix, off Kerguelen Islands, Antarctica ArchiMer
Delille, D.
Between January 1992 and March 1995, the research project Kerfix undertook the first regular non-coastal multiyear acquisition of parameters related to the carbon cycle in the Southern Ocean at a time series station located at 50degrees40'S-68degrees25'E, 110 km southwest of the Kerguelen Islands. I present here a general overview of the bacteriological data collected during this survey. Bacterioplankton biomass at Kerfix station was always significantly lower than in the direct vicinity of the Kerguelen Islands. Bacterial abundance decreased from surface to deepest layers (from 10(6) cells ml(-1) in surface layer to 5.0 x 10(4) cells ml(-1) at 1500 m). In contrast, mean cell volume (0.1 mum(3)) and proportion of free-living bacteria (80%) were relatively...
Tipo: Text Palavras-chave: Océan Antarctique; Biomasse bactérienne; Distribution verticale; Variations saisonnières; Variabilité interannuelle; Antarctic ocean; Bacterial biomass; Vertical distribution; Seasonal changes; Interannual variability.
Ano: 2003 URL: http://archimer.ifremer.fr/doc/00321/43268/42999.pdf
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Seasonal and intraseasonal biogeochemical variability in the thermocline ridge of the southern tropical Indian Ocean ArchiMer
Resplandy, L.; Vialard, Jerome; Levy, M.; Aumont, Olivier; Dandonneau, Y..
The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) time series shows high variability of surface chlorophyll at seasonal and intraseasonal time scales in the oligotrophic southern tropical Indian Ocean thermocline ridge called the Seychelles-Chagos thermocline ridge (SCTR). The SCTR is characterized by an open ocean upwelling due to local Ekman pumping, which annually maintains the mixed layer (ML) shallow and is responsive to atmospheric forcing and in particular to the Madden-Julian Oscillation (MJO) at an intraseasonal time scale. Here we present an overview of SCTR biogeochemistry and investigate the physical processes driving the response observed at seasonal and intraseasonal time scales. Using satellite observations and biophysical ocean...
Tipo: Text Palavras-chave: Madden julian oscillation; Arabian sea; Rossby waves; Interannual variability; Circulation model; Monsoon; Temperature; Perturbations; Nutrients; Dynamics.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00185/29630/27994.pdf
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Seasonal Mixed Layer Heat Balance of the Southwestern Tropical Indian Ocean ArchiMer
Foltz, Gregory R.; Vialard, Jerome; Kumar, B. Praveen; Mcphaden, Michael J..
Sea surface temperature (SST) in the southwestern tropical Indian Ocean exerts a significant influence on global climate through its influence on the Indian summer monsoon and Northern Hemisphere atmospheric circulation. In this study, measurements from a long-term moored buoy are used in conjunction with satellite, in situ, and atmospheric reanalysis datasets to analyze the seasonal mixed layer heat balance in the thermocline ridge region of the southwestern tropical Indian Ocean. This region is characterized by a shallow mean thermocline (90 m, as measured by the 20 degrees C isotherm) and pronounced seasonal cycles of Ekman pumping and SST (seasonal ranges of -0.1 to 0.6 m day(-1) and 26 degrees-29.5 degrees C, respectively). It is found that surface...
Tipo: Text Palavras-chave: Sea surface temperature; Pacific ocean; Equatorial pacific; Interannual variability; Bulk parameterization; Rainfall variability; Atlantic ocean; North pacific; El nino.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00185/29629/27996.pdf
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Subsurface structure of interannual temperature anomalies in the Australian sector of the Southern Ocean ArchiMer
Sokolov, S; Rintoul, Sr.
A 7 year time series of austral summer expendable bathythermograph (XBT) sections between Tasmania and Antarctica is used to describe the subsurface structure of Southern Ocean interannual temperature anomalies. Comparison of the discontinuous XBT record with a continuous (weekly average) satellite-based SST data set confirms that the XBT sampling is adequate to resolve interannual variability. Significant correlations are found between changes in surface and subsurface temperature along much of the section. In the Subantarctic zone, surface and subsurface changes are coherent because deep convection in winter homogenizes the upper 600 m, and the summer mixed layer temperature reflects the preconditioning of the previous winter. At other latitudes the...
Tipo: Text Palavras-chave: Antarctic circumpolar wave; Southern Ocean; Antarctic circumpolar current; Interannual variability; Decadal variability; Sea surface temperature anomaly.
Ano: 2003 URL: https://archimer.ifremer.fr/doc/00224/33550/32034.pdf
Registros recuperados: 23
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