Consulta: subjectFacets:"Ocean circulation"
Registros recuperados: 44
Data/hora: 03/06/2024 07:44:53

Available Potential Energy in Density Coordinates
Provedor de dados: 5
Autores: Colin De Verdiere, Alain; Huck, Thierry; Pogossian, Souren; Ollitrault, Michel.
The vertically integrated potential energy of an incompressible stratified fluid formulated in density coordinates can be simply written as a weighted vertical sum of the squares of the vertical displacements of density surfaces, a general expression valid for arbitrary displacements. The sum of this form of potential energy and kinetic energy is then a conserved quantity for the multilayer shallow water model. The formulation in density coordinates is a natural one to find the Lorenz reference state of available potential energy (APE).We describe the method to compute the APE of an ocean state and provide two applications. The first is the classical double-gyre, wind-driven circulation simulated by a shallow water model at high resolution.We show that the...
Tipo: Text
Palavras-chave: Energy transport; Ocean circulation; Ocean dynamics; Isopycnal coordinates.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00464/57521/59707.pdf

Impact of 4D-variational assimilation of WOCE hydrography on the meridional circulation of the Indian Ocean
Provedor de dados: 5
Autores: Ferron, Bruno; Marotzke, Jochem.
World Ocean Circulation Experiment (WOCE) hydrographic sections and a sea-surface climatology are combined with a ocean general circulation model through a 4D-variational method to analyze the meridional overturning of the Indian Ocean. The regional model is run with realistic surface forcings over year 1995 for which most of WOCE Indian Ocean sections were made. The assimilation controls the initial temperature and salinity fields, surface forcings and open-boundary velocities, temperature and salinity. When no observations are assimilated, the model shows that the deep (below 1000 m) meridional overturning is weak compared to observation-based estimates. This is a common feature of general circulation models. In contrast, after the assimilation, the...
Tipo: Text
Palavras-chave: Overturn; Oceanographic surveys; Hydrographic data; Ocean circulation.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2003/publication-582.pdf

Locations and mechanisms of ocean ventilation in the high-latitude North Atlantic in an eddy-permitting ocean model
Provedor de dados: 5
Autores: Macgilchrist, Graeme A.; Johnson, Helen L.; Marshall, David P.; Lique, Camille; Thomas, Matthew; Jackson, Laura C.; Wood, Richard A.
A substantial fraction of the deep ocean is ventilated in the high-latitude North Atlantic. Consequently, the region plays a crucial role in transient climate change through the uptake of carbon dioxide and heat. However, owing to the Lagrangian nature of the process, many aspects of deep Atlantic Ocean ventilation and its representation in climate simulations remain obscure. We investigate the nature of ventilation in the high latitude North Atlantic in an eddy-permitting numerical ocean circulation model using a comprehensive set of Lagrangian trajectory experiments. Backwards-in-time trajectories from a model-defined ‘North Atlantic DeepWater’ (NADW) reveal the locations of subduction from the surface mixed layer at high spatial resolution. The major...
Tipo: Text
Palavras-chave: North Atlantic Ocean; Atmosphere-ocean interaction; Lagrangian circulation/transport; Ocean circulation; Boundary currents; Diapycnal mixing.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00646/75833/76825.pdf

Lagrangian water mass tracing from pseudo-Argo, model-derived salinity, tracer and velocity data: An application to Antarctic Intermediate Water in the South Atlantic Ocean
Provedor de dados: 5
Autores: Blanke, Bruno; Speich, Sabrina; Rusciano, Emanuela.
We use the tracer and velocity fields of a climatological ocean model to investigate the ability of Argo-like data to estimate accurately water mass movements and transformations, in the style of analyses commonly applied to the output of ocean general circulation model. To this end, we introduce an algorithm for the reconstruction of a fully non-divergent three-dimensional velocity field from the simple knowledge of the model vertical density profiles and 1000-m horizontal velocity components. The validation of the technique consists in comparing the resulting pathways for Antarctic Intermediate Water in the South Atlantic Ocean to equivalent reference results based on the full model information available for velocity and tracers. We show that the...
Tipo: Text
Palavras-chave: Ocean circulation; Conservation equations; Mathematical models; Density field; Subsurface drifters; Intermediate water masses.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00238/34910/33597.pdf

Analyzing Large Paleoclimate Datasets: Implications for Past and Future Climate Change.
Provedor de dados: 5
Autores: Shakun, Jeremy D.
This dissertation presents the results of statistical analyses of large climate datasets from two time intervals – the 20th century instrumental record and the proxy record of the last deglaciation – in order to understand the forcings and mechanisms of past climate variability. A longstanding question in climate dynamics concerns the origin of Pacific decadal variability (PDV). This issue is addressed by calculating the Southern Hemisphere equivalent of the Pacific Decadal Oscillation (PDO) index from Pacific sea surface temperature (SST) anomalies over the 20th century, which is found to be similar to its Northern Hemisphere counterpart. The Northern and Southern PDO indices both exhibit pronounced seasonality in autocorrelation with interannual...
Tipo: Text
Palavras-chave: El Nino-Southern Oscillation; Pacific Decadal Oscillation; Paleoclimate; Deglaciation; Ocean circulation; Milankovitch; Greenhouse gases.
Ano: 2010
URL: https://archimer.ifremer.fr/doc/00495/60654/64151.pdf

A global inventory of small floating plastic debris
Provedor de dados: 5
Autores: Van Sebille, Erik; Wilcox, Chris; Lebreton, Laurent; Maximenko, Nikolai; Hardesty, Britta Denise; Van Franeker, Jan A.; Eriksen, Marcus; Siegel, David; Galgani, Francois; Law, Kara Lavender.
Microplastic debris floating at the ocean surface can harm marine life. Understanding the severity of this harm requires knowledge of plastic abundance and distributions. Dozens of expeditions measuring microplastics have been carried out since the 1970s, but they have primarily focused on the North Atlantic and North Pacific accumulation zones, with much sparser coverage elsewhere. Here, we use the largest dataset of microplastic measurements assembled to date to assess the confidence we can have in global estimates of microplastic abundance and mass. We use a rigorous statistical framework to standardize a global dataset of plastic marine debris measured using surface-trawling plankton nets and coupled this with three different ocean circulation models...
Tipo: Text
Palavras-chave: Marine debris; Ocean circulation; Model comparison.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00309/42053/41349.pdf

Recent advances in observing mesoscale ocean dynamics with satellite altimetry
Provedor de dados: 5
Autores: Morrow, Rosemary; Le Traon, Pierre-yves.
The paper provides a review of recent results on mesoscale ocean dynamics derived from satellite altimetry. Since 1992, we have had an unprecedented 18 year high-resolution monitoring of the ocean mesoscale field. Altimetry is often used in mesoscale studies in synergy with other remote sensing techniques and in situ data. This global, high-resolution data set has allowed oceanographers to quantify the previously unknown seasonal and interannual variations in eddy kinetic energy and eddy heat and salt transports, and investigate their causes. Eddy tracking techniques have allowed us to monitor their propagation pathways, to bring to light the meridional divergence of cyclones and anticyclones, and to question the role of Rossby waves versus non-linear...
Tipo: Text
Palavras-chave: Satellite altimetry; Mesoscale eddies; Ocean circulation.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00087/19847/17767.pdf

Challenges and Prospects in Ocean Circulation Models
Provedor de dados: 5
Autores: Fox-kemper, Baylor; Adcroft, Alistair; Boening, Claus W.; Chassignet, Eric P.; Curchitser, Enrique; Danabasoglu, Gokhan; Eden, Carsten; England, Matthew H.; Gerdes, Ruediger; Greatbatch, Richard J.; Griffies, Stephen M.; Hallberg, Robert W.; Hanert, Emmanuel; Heimbach, Patrick; Hewitt, Helene T.; Hill, Christopher N.; Komuro, Yoshiki; Legg, Sonya; Le Sommer, Julien; Masina, Simona; Marsland, Simon J.; Penny, Stephen G.; Qiao, Fangli; Ringler, Todd D.; Treguier, Anne-marie; Tsujino, Hiroyuki; Uotila, Petteri; Yeager, Stephen G.
We revisit the challenges and prospects for ocean circulation models following Griffies et al. (2010). Over the past decade, ocean circulation models evolved through improved understanding, numerics, spatial discretization, grid configurations, parameterizations, data assimilation, environmental monitoring, and process-level observations and modeling. Important large scale applications over the last decade are simulations of the Southern Ocean, the Meridional Overturning Circulation and its variability, and regional sea level change. Submesoscale variability is now routinely resolved in process models and permitted in a few global models, and submesoscale effects are parameterized in most global models. The scales where nonhydrostatic effects become...
Tipo: Text
Palavras-chave: Ocean circulation; Model; Parameterization; Climate; Ocean processes.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00488/59989/63213.pdf

Lagrangian ocean analysis: fundamentals and practices
Provedor de dados: 5
Autores: Van Sebille, Erik; Griffies, Stephen M.; Abernathey, Ryan; Adams, Thomas P.; Berloff, Pavel; Biastoch, Arne; Blanke, Bruno; Chassignet, Eric P.; Cheng, Yu; Cotter, Colin J.; Deleersnijder, Eric; Doos, Kristofer; Drake, Henri F.; Drijfhout, Sybren; Gary, Stefan F.; Heemink, Arnold W.; Kjellsson, Joakim; Koszalka, Inga Monika; Lange, Michael; Lique, Camille; Macgilchrist, Graeme A.; Marsh, Robert; Adame, C. Gabriela Mayorga; Mcadam, Ronan; Nencioli, Francesco; Paris, Claire B.; Piggott, Matthew D.; Polton, Jeff A.; Ruehs, Siren; Shah, Syed H. A. M.; Thomas, Matthew; Wang, Jinbo; Wolfram, Phillip J.; Zanna, Laure; Zika, Jan D.
Lagrangian analysis is a powerful way to analyse the output of ocean circulation models and other ocean velocity data such as from altimetry. In the Lagrangian approach, large sets of virtual particles are integrated within the three-dimensional, time-evolving velocity fields. Over several decades, a variety of tools and methods for this purpose have emerged. Here, we review the state of the art in the field of Lagrangian analysis of ocean velocity data, starting from a fundamental kinematic framework and with a focus on large-scale open ocean applications. Beyond the use of explicit velocity fields, we consider the influence of unresolved physics and dynamics on particle trajectories. We comprehensively list and discuss the tools currently available for...
Tipo: Text
Palavras-chave: Ocean circulation; Lagrangian analysis; Connectivity; Particle tracking; Future modelling.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00412/52324/53099.pdf

The timing of deglacial circulation changes in the Atlantic
Provedor de dados: 5
Autores: Waelbroeck, C.; Skinner, L. C.; Labeyrie, L.; Duplessy, J. -c.; Michel, E.; Vazquez Riveiros, Natalia; Gherardi, J. M.; Dewilde, F.
Well-dated benthic foraminifer oxygen isotopic records (delta O-18) from different water depths and locations within the Atlantic Ocean exhibit distinct patterns and significant differences in timing over the last deglaciation. This has two implications: on the one hand, it confirms that benthic delta O-18 cannot be used as a global correlation tool with millennial-scale precision, but on the other hand, the combination of benthic isotopic records with independent dating provides a wealth of information on past circulation changes. Comparing new South Atlantic benthic isotopic data with published benthic isotopic records, we show that (1) circulation changes first affected benthic delta O-18 in the 1000-2200 m range, with marked decreases in benthic delta...
Tipo: Text
Palavras-chave: Atlantic Ocean; Benthic oxygen isotope; Last deglaciation; Ocean circulation.
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00214/32517/31003.pdf

The Role of Curvature in Modifying Frontal Instabilities. Part II: Application of the Criterion to Curved Density Fronts at Low Richardson Numbers
Provedor de dados: 5
Autores: Buckingham, Christian; Gula, Jonathan; Carton, Xavier.
We continue our study of the role of curvature in modifying frontal stability. In Part I, we obtained an instability criterion valid for curved fronts and vortices in gradient wind balance (GWB): Φ′ = L′q′ &lt; 0, where L′ and q′ are the nondimensional absolute angular momentum and Ertel potential vorticity (PV), respectively. In Part II, we investigate this criterion in a parameter space representative of low-Richardson-number fronts and vortices in GWB. An interesting outcome is that, for Richardson numbers near 1, anticyclonic flows increase in q′, while cyclonic flows decrease in q′, tending to stabilize anticyclonic and destabilize cyclonic flow. Although stability is marginal or weak for anticyclonic flow (owing to multiplication by L′), the...
Tipo: Text
Palavras-chave: Eddies; Fronts; Instability; Ocean circulation; Potential vorticity; Frontogenesis/frontolysis; Vortices; Angular momentum.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00677/78919/81286.pdf

The Evolution of Deep Ocean Chemistry and Respired Carbon in the Eastern Equatorial Pacific Over the Last Deglaciation
Provedor de dados: 5
Autores: De La Fuente, Maria; Calvo, Eva; Skinner, Luke; Pelejero, Carles; Evans, David; Mueller, Wolfgang; Povea, Patricia; Cacho, Isabel.
It has been shown that the deep Eastern Equatorial Pacific (EEP) region was poorly ventilated during the Last Glacial Maximum (LGM) relative to Holocene values. This finding suggests a more efficient biological pump, which indirectly supports the idea of increased carbon storage in the deep ocean contributing to lower atmospheric CO2 during the last glacial. However, proxies related to respired carbon are needed in order to directly test this proposition. Here we present Cibicides wuellerstorfi B/Ca ratios from Ocean Drilling Program Site 1240 measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) as a proxy for deep water carbonate saturation state ([CO32-], and therefore [CO32-]), along with C-13 measurements. In addition, the...
Tipo: Text
Palavras-chave: Marine carbon cycle; Carbonate chemistry; Ocean circulation; Glacial-interglacial cycles; Soft-tissue pump efficiency; Seafloor calcite dissolution.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00497/60824/64598.pdf

Size sorting in marine muds: Processes, pitfalls, and prospects for paleoflow-speed proxies
Provedor de dados: 5
Autores: Mccave, I. N.; Hall, I. R.
The basis for, and use of, fine grain size parameters for inference of paleoflow speeds is reviewed here. The basis resides in data on deposited sediment taken in conjunction with flow speed measurements in the field, experimental data on suspended sediment transport and deposition, and theoretical treatments of the generation of size distributions of deposits from suspension controlled by particle settling velocity and flow speed. In the deep sea, sorting events occur under resuspension/deposition events in benthic storms. At flow speeds below 10 - 15 cm s(-1), size in the noncohesive "sortable silt'' ( 10 - 63 mm) range is controlled by selective deposition, whereas above that range, removal of finer material by winnowing also plays a role. The best...
Tipo: Text
Palavras-chave: Sortable silt; Grain size; Paleocurrent; Flow speed; Ocean circulation; Contourite; Sediment drift.
Ano: 2006
URL: https://archimer.ifremer.fr/doc/00234/34515/33417.pdf

Which is the better proxy for paleo-current strength: Sortable-silt mean size (SS) or sortable-silt mean grain diameter (d SS)? A case study from the Nordic Seas
Provedor de dados: 5
Autores: Tegzes, Andrea D.; Jansen, Eystein; Telford, Richard J.
The coarseness of the 10-63 m terrigenous silt (i.e., sortable-silt) fraction tends to vary independently of sediment supply in current-sorted muds in the world's oceans, with coarser sediments representing relatively greater near-bottom flow speeds. Traditionally, the coarseness of this size fraction is described using an index called sortable-silt mean size ( SS), which is an arithmetic average calculated from the differential volume or mass distribution of grains within the 10-63 m terrigenous silt fraction, where the relative weights of the individual size bins become increasingly disproportionate, with respect to the actual number of grains within those size bins, toward the coarse end of the size range. This not only increases the absolute value of...
Tipo: Text
Palavras-chave: Ocean circulation; Paleo-current reconstructions; Sortable-silt mean size; Sortable-silt mean grain size; Coulter Counter.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00496/60728/65240.pdf

Evolution of neodymium isotopic signature of seawater during the Late Cretaceous: Implications for intermediate and deep circulation
Provedor de dados: 5
Autores: Moiroud, Mathieu; Puceat, Emmanuelle; Donnadieu, Yannick; Bayon, Germain; Guiraud, Michel; Voigt, Silke; Deconinck, Jean-francois; Monna, Fabrice.
Neodymium isotopic compositions (εNd) have been largely used for the last fifty years as a tracer of past ocean circulation, and more intensively during the last decade to investigate ocean circulation during the Cretaceous period. Despite a growing set of data, circulation patterns still remain unclear during this period. In particular, the identification of the deep-water masses and their spatial extension within the different oceanic basins are poorly constrained. In this study we present new deep-water εNd data inferred from the Nd isotope composition of fish remains and Fe-Mn oxyhydroxide coatings on foraminifera tests, along with new εNd data of residual (partly detrital) fraction recovered from DSDP sites 152 (Nicaraguan Rise), 258 (Naturaliste...
Tipo: Text
Palavras-chave: Cretaceous; Neodymium isotopes; Ocean circulation; Southern Ocean.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00278/38962/37502.pdf

Geostrophic Closure of the Zonally Averaged Atlantic Meridional Overturning Circulation
Provedor de dados: 5
Autores: Sevellec, Florian; Huck, Thierry.
It is typically assumed that the meridional density gradient in the North Atlantic is well and positively correlated with the Atlantic meridional overturning circulation (AMOC). In numerical "water-hosing" experiments, for example, imposing an anomalous freshwater flux in the Northern Hemisphere leads to a slowdown of the AMOC. However, on planetary scale, the first-order dynamics are linked to the geostrophic balance, relating the north-south pressure gradient to the zonal circulation. In this study, these two approaches are reconciled. At steady state and under geostrophic dynamics, an analytical expression is derived to relate the zonal and meridional pressure gradient. This solution is only valid where the meridional density gradient length scale is...
Tipo: Text
Palavras-chave: Meridional overturning circulation; Thermohaline circulation; Atm/Ocean Structure/ Phenomena; Ocean circulation; Baroclinic flows; Geographic location/entity; Ekman pumping; Circulation/ Dynamics; Atlantic Ocean.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00323/43456/42843.pdf

Subantarctic Mode Water Formation, Destruction, and Export in the Eddy-Permitting Southern Ocean State Estimate
Provedor de dados: 5
Autores: Cerovecki, Ivana; Talley, Lynne D.; Mazloff, Matthew R.; Maze, Guillaume.
Subantarctic Mode Water (SAMW) is examined using the data-assimilating, eddy-permitting Southern Ocean State Estimate, for 2005 and 2006. Surface formation due to air–sea buoyancy flux is estimated using Walin analysis, and diapycnal mixing is diagnosed as the difference between surface formation and transport across 30°S, accounting for volume change with time. Water in the density range 26.5 &lt; σθ &lt; 27.1 kg m−3 that includes SAMW is exported northward in all three ocean sectors, with a net transport of (18.2, 17.1) Sv (1 Sv ≡ 106 m3 s−1; for years 2005, 2006); air–sea buoyancy fluxes form (13.2, 6.8) Sv, diapycnal mixing removes (−14.5, −12.6) Sv, and there is a volume loss of (−19.3, −22.9) Sv mostly occurring in the strongest SAMW formation...
Tipo: Text
Palavras-chave: Atmosphere-ocean interaction; Buoyancy; Fluxes; Ocean circulation.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00154/26487/24596.pdf

Ocean circulation reconstructions from epsilon(Nd): A model-based feasibility study
Provedor de dados: 5
Autores: Friedrich, T.; Timmermann, A.; Stichel, T.; Pahnke, K.
Over the past decade, records of the seawater neodymium isotopic composition (epsilon(Nd)) have become a widely used proxy to reconstruct changes in ocean circulation. Our study investigates the transient response of epsilon(Nd) to large-scale ocean circulation changes using an Earth system model of intermediate complexity. It is shown that a weakening of the North Atlantic Deep Water formation results in positive epsilon(Nd) anomalies in the Atlantic and the Pacific below 1000m water depth whereas variations in Antarctic Bottom Water production generate a Pacific-Atlantic dipole pattern of deep ocean epsilon(Nd) changes. Further experiments explore which ocean regions are suitable to record the temporal evolution of the overturning in the North Atlantic...
Tipo: Text
Palavras-chave: Neodymium; Ocean circulation; Meridional overturning; Ocean modeling; Reconstruction.
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00289/40055/39405.pdf

Glacial Ocean Dynamics: Insight from Deep-Sea Coral Reconstructions and A Time-Dependent Dynamical Box Model
Provedor de dados: 5
Autores: Hines, Sophia Katharine Vizza.
Glacial-interglacial cycles, occurring at a period of approximately 100,000 years, have dominated Earth's climate over the past 800,000 years. These cycles involve major changes in land ice, global sea level, ocean circulation, and the carbon cycle. While it is generally agreed that the ultimate driver of global climate is changes in insolation, glacial cycles do not look like insolation forcing. Notably, there is a highly non-linear warming response at 100,000 years to a relatively small forcing, implicating a more complicated system of biogeochemical and physical drivers. The ocean plays a pivotal role in glacial-interglacial climate through direct equator-to-pole transport of heat and its role in the carbon cycle. The deep ocean contains 60 times more...
Tipo: Text
Palavras-chave: Paleoceanography; Oceanography; Climate change; Glacial cycles; Ocean circulation; Ocean dynamics.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00493/60447/63892.pdf

Atlantic Meridional Overturning Circulation during the Last Glacial and Deglacial: Inferences from the Atlantic Tropical Thermocline Temperature and Seawater Radiocarbon Activity
Provedor de dados: 5
Autores: Huang, Enqing.
This thesis aims to investigate variations of the last glacial and deglacial Atlantic Ocean circulation, with emphasize on the Atlantic deepwater ventilation rate during the Last Glacial Maximum (LGM). The highlights of the thesis are as the followings: (1) the modern frontal zone between the North Atlantic and the South Atlantic central waters off NW Africa shifted to the south during the last glacial and deglacial time periods. (2) The radiocarbon-based circulation age of the deep Atlantic (&gt; 1500 m) was estimated to be less than 400 years during the LGM, which was equal to or less than its pre-bomb value. Therefore, the LGM deep Atlantic was inferred to be well ventilated. (3) The abyssal Atlantic (below 2500 m) prior to the LGM was more depleted in...
Tipo: Text
Palavras-chave: Climate change; Ocean circulation; Atlantic Ocean; Glacial; Deglacial; Thermocline; Radiocarbon; Global carbon cycle; Foraminifera; Carbonate; Trace elements; Deep ocean ventilation rates.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00493/60446/63891.pdf

Multiple jets of the Antarctic circumpolar current South of Australia
Provedor de dados: 5
Autores: Sokolov, Serguei; Rintoul, Stephen R.
Maps of the gradient of sea surface height (SSH) and sea surface temperature (SST) reveal that the Antarctic Circumpolar Current (ACC) consists of multiple jets or frontal filaments. The braided and patchy nature of the gradient fields seems at odds with the traditional view, derived from hydrographic sections, that the ACC is made up of three continuous circumpolar fronts. By applying a nonlinear fitting procedure to 638 weekly maps of SSH gradient (del SSH), it is shown that the distribution of maxima in del SSH (i.e., fronts) is strongly peaked at particular values of absolute SSH (i.e., streamlines). The association between the jets and particular streamlines persists despite strong topographic and eddy - mean flow interactions, which cause the jets to...
Tipo: Text
Palavras-chave: Jets; Currents; Sea surface temperature; Ocean circulation.
Ano: 2007
URL: https://archimer.ifremer.fr/doc/00235/34616/32952.pdf

Decadal oscillations in a simplified coupled model due to unstable interactions between zonal winds and ocean gyres
Provedor de dados: 5
Autores: Arzel, Olivier; Huck, Thierry.
A simplified coupled ocean-atmosphere model, consisting of a one-layer bidimensional ocean model and a one-layer unidimensional energy balance atmospheric model [J. Clim. 13 (2000) 232] is used to study the unstable interactions between zonal winds and ocean gyres. In a specific range of parameters, decadal variability is found. Anomalies, quite homogeneous zonally, show small-scale wavelength in latitude: perturbations emerge and grow at the southern limb of the intergyre boundary and propagate southward before decaying. The wind stress anomalies are proportional to the meridional gradient of the atmospheric temperature anomalies: this ratio acts as a positive amplification factor, as confirmed by a parameter sensitivity analysis. Assuming...
Tipo: Text
Palavras-chave: Ocean atmosphere system; Air sea interaction; Air sea coupling; Ocean circulation.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2003/publication-647.pdf

Radiocarbon age of late glacial deep water from the equatorial Pacific
Provedor de dados: 5
Autores: Broecker, Wallace; Clark, Elizabeth; Barker, Stephen; Hajdas, Irena; Bonani, Georges; Moreno, Eva.
Radiocarbon age differences for pairs of coexisting late glacial age benthic and planktic foraminifera shells handpicked from 10 sediment samples from a core from a depth of 2.8 km in the western equatorial Pacific are not significantly different from that of 1600 years calculated from measurements on prenuclear seawater. This places a lower limit on the depth of the interface for the hypothetical radiocarbon-depleted glacial age seawater reservoir required to explain the 190% drop in the (14)C/C for atmospheric CO(2), which occurred during the mystery interval (17.5 to 14.5 calendar years ago). These measurements restrict the volume of this reservoir to be no more than 35% that of the ocean. Further, (14)C measurements on a single Last Glacial Maximum age...
Tipo: Text
Palavras-chave: Ocean circulation; Mystery interval; Radiocarbon dating.
Ano: 2007
URL: https://archimer.ifremer.fr/doc/00233/34449/32884.pdf

Tasman leakage: A new route in the global ocean conveyor belt - art. no. 1416
Provedor de dados: 5
Autores: Speich, Sabrina; Blanke, Bruno; De Vries, Pedro; Drijfhout, Sybren; Doos, Kristofer; Ganachaud, Alexandre; Marsh, Robert.
[1] The existence of a new route that draws relatively cold waters from the Pacific Ocean to the North Atlantic via the Tasman outflow is presented. The new route materialises with comparable magnitude and characteristics in three independent numerical realisations of the global ocean circulation. Its realism is supported by hydrographic data interpolated via an inverse model. The "Tasman leakage'' constitutes a sizeable component of the upper branch of the global conveyor belt and represents an extension to the prevailing views that hitherto emphasised the routes via the Drake Passage and the Indonesian Throughflow [Gordon, 1986].
Tipo: Text
Palavras-chave: Numerical model; Ocean circulation.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-771.pdf

ANDRO: An Argo-Based Deep Displacement Dataset
Provedor de dados: 5
Autores: Ollitrault, Michel; Rannou, Jean Philippe.
During the first decade of the twenty-first century, more than 6000 Argo floats have been launched over the World Ocean, gathering temperature and salinity data from the upper 2000 m, at a 10-day or so sampling period. Meanwhile their deep displacements can be used to map the ocean circulation at their drifting depth (mostly around 1000 m). A comprehensive processing of the whole Argo dataset collected prior to 1 January 2010 has been performed to produce a world-wide dataset of deep displacements. This numerical atlas, named ANDRO, after a traditional dance of Brittany meaning a swirl, comprises some 600 000 deep displacements. These displacements, based on Argo or GPS surface locations only, have been fully checked and corrected for possible errors found...
Tipo: Text
Palavras-chave: Lagrangian circulation/transport; Large-scale motions; Ocean circulation.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00138/24901/22994.pdf

Circulation around La Reunion and Mauritius islands in the south-western Indian Ocean: A modeling perspective
Provedor de dados: 5
Autores: Pous, Stephane; Lazure, Pascal; Andre, Gael; Dumas, Franck; Halo, Issufo; Penven, Pierrick.
Circulation around both islands is dominated by westward propagating features The predominant time scale of variability of currents and SSH is 60 days There is local generation of eddies in the lee of the islands due to topography
Tipo: Text
Palavras-chave: Ocean circulation; Hydrodynamic model; La Reunion; Eddies; Rossby waves.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00195/30624/29073.pdf

A numerical modeling study of the Southern Senegal upwelling shelf: Circulation and upwelling source waters
Provedor de dados: 5
Autores: Ndoye, S; Capet, Xavier; Estrade, Philippe; Machu, Eric; Kounta, L; Sow, B; Diakhate, M; Gayet, At.
The regional ocean circulation along the Southern Senegal shelf is studied using a numerical model for varying forcing fields during the upwelling season (November-May). The main objective is to study the shelf circulation of the marine environment in the Southern Senegal Upwelling Shelf (SSUS), the Lagrangian pathways by which waters are transported to the surface in the upwelling tongue and the fate of these waters. Model results are compared with hydrographic measurements during UPSEN2-ECOAO survey and satellite images datasets. The upwelling source waters and also the warm nearshore waters are analyzed, from a Lagrangian point of view, by computing the paths of particles that are passively advected by the regional ocean model velocity field (ROMS). It...
Tipo: Text
Palavras-chave: Upwelling; Ocean circulation; Modeling; Coastal dynamics; Shelf; ROMS.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00472/58346/60900.pdf

The Ocean General Circulation near 1000-m Depth
Provedor de dados: 5
Autores: Ollitrault, Michel; Colin De Verdiere, Alain.
The mean ocean circulation near 1000-m depth is estimated with 100-km resolution from the Argo float displacements collected before 1 January 2010. After a thorough validation, the 400 000 or so displacements found in the 950–1150 dbar layer and with parking times between 4 and 17 days allow the currents to be mapped at intermediate depths with unprecedented details. The Antarctic Circumpolar Current (ACC) is the most prominent feature, but western boundary currents (and their recirculations) and alternating zonal jets in the tropical Atlantic and Pacific are also well defined. Eddy kinetic energy (EKE) gives the mesoscale variability (on the order of 10 cm2 s−2 in the interior), which is compared to the surface geostrophic altimetric EKE showing e-folding...
Tipo: Text
Palavras-chave: Circulation; Dynamics; Currents; Dynamics; Large-scale motions; Ocean circulation.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00174/28512/26877.pdf

Dynamical reconstruction of the global ocean state during the Last Glacial Maximum
Provedor de dados: 5
Autores: Kurahashi-nakamura, Takasumi; Paul, Andre; Losch, Martin.
The global ocean state for the modern age and for the Last Glacial Maximum (LGM) was dynamically reconstructed with a sophisticated data assimilation technique. A substantial amount of data including global seawater temperature, salinity (only for the modern estimate), and the isotopic composition of oxygen and carbon (only in the Atlantic for the LGM) were integrated into an ocean general circulation model with the help of the adjoint method, thereby the model was optimized to reconstruct plausible continuous fields of tracers, overturning circulation and water mass distribution. The adjoint-based LGM state estimation of this study represents the state of the art in terms of the length of forward model runs, the number of observations assimilated, and the...
Tipo: Text
Palavras-chave: Last Glacial Maximum; Ocean circulation; AMOC; Proxy records; Ocean general circulation model; Data assimilation.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00383/49466/49951.pdf

Radiocarbon evidence for alternating northern and southern sources of ventilation of the deep Atlantic carbon pool during the last deglaciation
Provedor de dados: 5
Autores: Skinner, Luke C.; Waelbroeck, Claire; Scrivner, Adam E.; Fallon, Stewart J.
Recent theories for glacial-interglacial climate transitions call on millennial climate perturbations that purged the deep sea of sequestered carbon dioxide via a "bipolar ventilation seesaw." However, the viability of this hypothesis has been contested, and robust evidence in its support is lacking. Here we present a record of North Atlantic deep-water radiocarbon ventilation, which we compare with similar data from the Southern Ocean. A striking coherence in ventilation changes is found, with extremely high ventilation ages prevailing across the deep Atlantic during the last glacial period. The data also reveal two reversals in the ventilation gradient between the deep North Atlantic and Southern Ocean during Heinrich Stadial 1 and the Younger Dryas....
Tipo: Text
Palavras-chave: Ocean circulation; Carbon cycle; Abrupt change.
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00290/40153/39327.pdf

Variation that can be expected when using particle tracking models in connectivity studies
Provedor de dados: 5
Autores: Hufnagl, Marc; Payne, Mark; Lacroix, Genevieve; Bolle, Loes J.; Daewele, Ute; Dickey-collas, Mark; Gerkema, Theo; Huret, Martin; Janssen, Frank; Kreus, Markus; Paetsch, Johannes; Pohlmann, Thomas; Ruardij, Piet; Schrum, Corinna; Skogen, Morten D.; Tiessen, Meinard C. H.; Petitgas, Pierre; Van Beek, Jan K. L.; Van Der Veer, Henk W.; Callies, Ulrich.
Hydrodynamic Ocean Circulation Models and Lagrangian particle tracking models are valuable tools e.g. in coastal ecology to identify the connectivity between offshore spawning and coastal nursery areas of commercially important fish, for risk assessment and more for defining or evaluating marine protected areas. Most studies are based on only one model and do not provide levels of uncertainty. Here this uncertainty was addressed by applying a suite of 11 North Sea models to test what variability can be expected concerning connectivity. Different notional test cases were calculated related to three important and well-studied North Sea fish species: herring (Clupea harengus), and the flatfishes sole (Solea solea) and plaice (Pleuronectes platessa). For sole...
Tipo: Text
Palavras-chave: Ocean circulation; Lagrangian approach; Variability; Marine protected areas; Renewable energy; Wind park; Model intercomparison; Ensemble.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00385/49660/50198.pdf

Can We Infer Diapycnal Mixing Rates from the World Ocean Temperature-Salinity Distribution?
Provedor de dados: 5
Autores: Arzel, Olivier; Colin De Verdiere, Alain.
The turbulent diapycnal mixing in the ocean is currently obtained from microstructure and finestructure measurements, dye experiments, and inverse models. This study presents a new method that infers the diapycnal mixing from low-resolution numerical calculations of the World Ocean whose temperatures and salinities are restored to the climatology. At the difference of robust general circulation ocean models, diapycnal diffusion is not prescribed but inferred. At steady state the buoyancy equation shows an equilibrium between the large-scale diapycnal advection and the restoring terms that take the place of the divergence of eddy buoyancy fluxes. The geography of the diapycnal flow reveals a strong regional variability of water mass transformations....
Tipo: Text
Palavras-chave: Diapycnal mixing; Eddies; Meridional overturning circulation; Mixing; Ocean circulation; General circulation models.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00600/71197/69563.pdf

The Internal Generation of the Atlantic Ocean Interdecadal Variability
Provedor de dados: 5
Autores: Arzel, Olivier; Huck, Thierry; Colin De Verdiere, Alain.
Numerical simulations of a realistic ocean general circulation model forced by prescribed surface fluxes are used to study the origin and structure of intrinsic interdecadal variability of the ocean circulation. When eddy-induced turbulent diffusivities are low enough, spontaneous oscillations of the Atlantic meridional overturning circulation (AMOC) with periods O(20) yr and amplitude O(1) Sv (1 Sv ≡ 106 m3 s−1) emerge. The transition from the steady to the oscillatory regime is shown to be consistent with a supercritical Hopf bifurcation of the horizontal Peclet number. Adding atmospheric thermal damping is shown to have a very limited influence on the domain of existence of intrinsic variability. The spatial structure of the mode consists of a dipole of...
Tipo: Text
Palavras-chave: Instability; Meridional overturning circulation; Ocean circulation; Planetary waves; Climate variability; Multidecadal variability.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00464/57522/59708.pdf

Global Temperature-Salinity Profile Programme (GTSPP) - Overview and Future
Provedor de dados: 20
Autores: Wilson, J.R.
This document is directed to the scientific research community and users of operational ocean data. It is also intended to provide an example and be a source of information to programmes such as the Global Ocean Observing System (GOOS) for developing and implementing end-to-end data management systems. The document is also directed towards Member States of IOC. It discusses how Member States can make contributions and how they can benefit from the GTSPP.
Tipo: Report
Palavras-chave: Oceanography; Temperature data; Temperature measurement; Ocean circulation; Salinity; Salinity data; Salinity measurement; Salinity profiles; Salinity scales; Salinity.
Ano: 1998
URL: http://hdl.handle.net/1834/2796

Modelado numérico del ecosistema de los golfos norpatagónicos
Provedor de dados: 20
Autores: Tonini, M.H.
This dissertation analyses the oceanic circulation of the Norpatagonian Gulfs, a region of the Argentinean Sea that has long been recognized for the high productivity and biodiversity of the ecosystem. The study aims towards a systematic exploration of the physical processes that control the circulation using a high resolution three dimensional numerical model. To facilitate the dynamical understanding of the results our experimental strategy was to start with a constant density (barotropic) model forced by tides and winds, and to progress to a more complex case including density stratification generated by surface fluxes of heat and humidity. The main result that stems from the numerical experiments is that tidal forcing significantly contributes to the...
Tipo: Theses and Dissertations
Palavras-chave: Water masses; Oceanography; Currents (water); Fronts; Ocean circulation; Mathematical models; Tides; Winds; Physical oceanography; Tides; Winds; Physical oceanography; Oceanography; Mathematical models.
Ano: 2010
URL: http://hdl.handle.net/1834/3877

Estudio numérico de circulación océanica sobre la plataforma continental argentina
Provedor de dados: 20
Autores: Sitz, L.E.
This dissertation analyses the barotropic and baroclinic response of the Argentinean Continental Shelf to different forcing using a three-dimensional numerical ocean model. The study aims towards a systematical exploration of the physical processes that control the circulation. To facilitate the dynamical understanding of the results our experimental strategy was to start with a three dimensional barotropic model (constant density) that examines the influence of winds and tides, and to progress to a more complex case including density stratification (baroclinic model). It was found that the average annual circulation, forced only by the wind, shows a strong contrast between the northern and southern region of the study area. A detailed analysis...
Tipo: Theses and Dissertations
Palavras-chave: Numerical analysis; Water masses; Mathematical models; Physical oceanography; Current data; Tides; Winds; Ocean circulation; Physical oceanography; Tides; Winds; Mathematical models.
Ano: 2009
URL: http://hdl.handle.net/1834/3878

Protocols for the Joint Global Ocean Flux Study (JGOFS) Core Measurements
Provedor de dados: 20
This manual describes the protocol approved by the international Scientific Steering Committee for the Joint Global Ocean Flux Study (JGOFS) for the most of the 20 JGOFS Core Measurements. However, the methods for the analysis of various parameters of the seawater CO2 system are described in a separate handbook. In order to have a complete set of the JGOFS measurements protocols, you should request a copy of the "Handbook of Methods for the Analysis of the Various Parameters of the Carbon Dioxide System in Seawater"version 2, A.G. Dickson and C. Goyet, eds. ORNL/CDIAC-74.
Tipo: Book
Palavras-chave: Oceanography; Ocean circulation; Oceanographic stations; Oceanographic data; Oceanographic surveys; Samples; Sampling; Data processing; Data; Data collections; Quality control; Salinity measurement; Oxygen; Inorganic carbon; Nitrites; Nitrates; Phosphorus compounds; Phosphorus cycle; Silicate minerals; Marine organisms; Microorganisms; Bacteriology; Bacteria; Zooplankton; Sampling; Nitrites; Nitrates; Zooplankton; Data processing; Data; Oxygen; Microorganisms; Bacteriology; Bacteria; Http://aims.fao.org/aos/agrovoc/c_6774; Http://aims.fao.org/aos/agrovoc/c_5190; Http://aims.fao.org/aos/agrovoc/c_5187; Http://aims.fao.org/aos/agrovoc/c_15490; Http://aims.fao.org/aos/agrovoc/c_10289; Http://aims.fao.org/aos/agrovoc/c_49816; Http://aims.fao.org/aos/agrovoc/c_5477; Http://aims.fao.org/aos/agrovoc/c_4807; Http://aims.fao.org/aos/agrovoc/c_768; Http://aims.fao.org/aos/agrovoc/c_765.
Ano: 1994
URL: http://hdl.handle.net/1834/2795

Global Temperature-Salinity Profile Programme (GTSPP) - Overview and Future
Provedor de dados: 20
Autores: Wilson, J.R.
This document is directed to the scientific research community and users of operational ocean data. It is also intended to provide an example and be a source of information to programmes such as the Global Ocean Observing System (GOOS) for developing and implementing end-to-end data management systems. The document is also directed towards Member States of IOC. It discusses how Member States can make contributions and how they can benefit from the GTSPP.
Tipo: Book
Palavras-chave: Oceanography; Temperature data; Temperature measurement; Ocean circulation; Salinity; Salinity data; Salinity measurement; Salinity profiles; Salinity scales; Salinity; Http://aims.fao.org/aos/agrovoc/c_6751.
Ano: 1998
URL: http://hdl.handle.net/1834/2796

Esquema de circulación del Golfo de Batabanó
Provedor de dados: 20
Autores: Simanca, J.; Fernández, L.; Viamontes, J.; Ramírez, O.; Arriaza, L.; Ochoa, J.L.
Se modificó el patrón de circulación en la periferia acuática del Golfo de Batabanó a partir de la caracterización estadística de la corriente residual filtrada de series temporales provenientes de 12 estaciones correntométricas obtenidas de julio de 1988 a agosto de 1989. Para el filtraje de la componente no periódica se utilizó el filtro Doodson. Los resultados muestran que las corrientes residuales son débiles, con intensidades que variaron entre 1.2 - 5.5 cm/s como promedio por estaciones, además, las velocidades resultaron ser más estables en dirección que en intensidad. Se observó salida de agua por el extremo SE del golfo y por algunos canales al E de la Isla de la Juventud, y entrada de agua por el E del golfo en su límite con el Golfo de Cazones y...
Tipo: Conference Material
Palavras-chave: Time series; Current measurement; Coastal currents; Ocean circulation.
Ano: 2006
URL: http://hdl.handle.net/1834/2230

Corrientes en la plataforma continental
Provedor de dados: 20
Autores: Piola, A.R.; Rivas, A.
In this chapter the main features of the currents on the Argentine continental shelf are described. Due to the scarcity of direct current observations, adequate to resolve the mean flow, the circulation of the continental shelf is studied based on property distributions and models. These analyses indicate that the mean flowover the continental shelf varies between 1 and 2 Sverdrups (1Sverdrup = 1x106 m3 s-1)towards the NNE. A synthesis of results of studies of higher frequency motions is also presented. The most relevant results derived from long term direct current observations on the continental shelf near 43°S are discussed. The mean current velocities in the inner and mid-shelf regions vary between 0,05 and 0,10 m/s towards the NNE, in agreement with...
Tipo: Book Section
Palavras-chave: Continental shelves; Ocean currents; Ocean circulation; Physical oceanography; Ocean currents; Physical oceanography; Continental shelves; Http://aims.fao.org/aos/agrovoc/c_12883; Http://aims.fao.org/aos/agrovoc/c_5830; Http://aims.fao.org/aos/agrovoc/c_32413.
Ano: 1997
URL: http://hdl.handle.net/1834/1704

Utilización de datos satelitarios en investigaciones oceanográficas y pesqueras en el océano Atlántico sudoccidental
Provedor de dados: 20
Autores: Podestá, G.
The use of satellite data in oceanographic and fishery studies in the SW Atlantic is reviewed. First, terms commonly used in the remote sensing literature are defined. The main satellite sensors used in oceanographic applications are described, and the principles of the remote estimation of two important variables, sea surface temperature(SST)and ocean color, are discussed. The use of remotely sensed data in oceanographic studies of the SW Atlantic is reviewed. Most studies are based on satellite SST fields and describe circulation in the open, particularly near the confluence of the Brazil and Malvinas currents. Due to the limited number of fishery studies based on satellite data in the SW Atlantic, examples from other parts of the world are reviewed....
Tipo: Book Section
Palavras-chave: Remote sensing; Satellite sensing; Oceanographic surveys; Fishery surveys; Fishery oceanography; Ocean circulation; Fishery oceanography; Remote sensing; Http://aims.fao.org/aos/agrovoc/c_2938; Http://aims.fao.org/aos/agrovoc/c_6498.
Ano: 1997
URL: http://hdl.handle.net/1834/1724

Presencia de la corriente costanera ecuatoriana
Provedor de dados: 20
Autores: Allauca, S.
Se realiza un breve resumen de estudios previos acerca de la circulación oceánica en el área del Pacífico Oriental Ecuatorial, haciendo énfasis en la zona frente a las costas del Ecuador. Posteriormente se analizan los datos de derivas y vientos tomados por el B/I ORION durante sus Cruceros de Investigación desde 1982, excluyendo aquellas observadas durante El Niño 82-83 y la información existente al oeste de 84° W. Del análisis de la información de derivas obtenidas durante casi todos los meses del año, se observa que el ramal oriental de la Corriente de Humboldt avanza con tendencia al norte bordeando las costas ecuatorianas, debido principalmente al empuje de los vientos alisios del SE. Este flujo denominado Corriente Costanera Ecuatoriana (CCE) gira...
Tipo: Journal Contribution
Palavras-chave: Ocean circulation; Intertropical convergence zone; Ocean currents; Ocean currents; Http://aims.fao.org/aos/agrovoc/c_12883.
Ano: 1990
URL: http://hdl.handle.net/1834/2168

Circulación y estructura termohalina en una región del Pacífico Oriental (03°16'S-31°23'S) durante un período de El Niño 1997-1998
Provedor de dados: 20
Autores: Zambrano, E.; Garcés Vargas, J.
El objetivo del presente trabajo es estudiar la estructura termohalina superficial y subsuperficial de una región del Pacífico Sudeste (Guayaquil-Valparaíso), Fig. 1, durante el término de la primavera austral de 1997 para determinar los posibles cambios en la circulación. Para esta fecha se dio comienzo la VII Expedición Ecuatoriana a la Antártida a bordo del B/I ORION y simultáneamente se estaba desarrollando un evento ENOS de intensidad fuerte.
Tipo: Journal Contribution
Palavras-chave: El Nino phenomena; Thermohaline circulation; Surface temperature; T/S diagrams; Current direction; Countercurrents; Current measurement; Ocean circulation.
Ano: 1998
URL: http://hdl.handle.net/1834/2316

Distribución de las corrientes alrededor de las Islas Galápagos
Provedor de dados: 20
Autores: Lucero, M.
De la información de corrientes, obtenidas en forma directa con un correntómetro ADCP WHS300, durante el Crucero Oceanográfico realizado desde el 31 de julio al 16 de agosto del 2000, se determinó el patrón de circulación alrededor de las Islas Galápagos, el mismo que no sigue estrictamente la distribución encontrada en forma global por otros autores. La circulación en el área de estudio está principalmente gobernada por la presencia de los fuertes afloramientos producidos al oeste de las islas, por la topografía submarina del Archipiélago y por la presencia de las derivas superficiales hacia el oeste, producto de la convergencia de las Corrientes Sur Ecuatorial y Corriente de Humboldt. Los mayores flujos fueron observados en los niveles superficiales en...
Tipo: Journal Contribution
Palavras-chave: Current data; Oceanographic equipment; Cruises; Acoustic current meters; Oceanic islands; Ocean circulation; Coastal upwelling.
Ano: 2000
URL: http://hdl.handle.net/1834/2243