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Climatologie fine des systèmes de vagues pour l'étude des systèmes houlomoteurs ArchiMer
Saulnier, Jean Baptiste.
This work focuses on the refinement of sea-states spectral characterisation in the frame of the development of wave energy converters (WECs). Until now, this characterisation has been limited to the consideration of basic global parameters such as the significant wave height and mean wave period. The present work namely underlines - thanks to simplified numerical models - that such a description is not sufficient to account for the performance of WECs, for they still exhibit a large variability in terms of mean production while wave energy and period are fixed. It is therefore needed to refine this description by introducing new wave characteristics, such as the wave groupiness, which is itself related to the sea-state's spectral bandwidth. The classical -...
Tipo: Text Palavras-chave: Modèles stochastiques; Processus gaussiens; Simulations numériques; Cohérence spatio temporelle; Systèmes de vagues; Densité spectrale; État de mer; Largeur spectrale; Groupement de vagues; Systèmes houlomoteurs; Énergie des vagues; Stochastic models; Gaussian processes; Numerical simulations; Spatiotemporal coherence; Wave system; Spectral density; Sea state; Spectral bandwidth; Wave groupiness; WECs; Wave energy.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/these-7414.pdf
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Combined wind vector and sea state impact on ocean nadir-viewing Ku- and C-band radar cross-sections ArchiMer
Tran, Ngan; Chapron, Bertrand.
The authors report the first results in studying the polarization anisotropy of the microwave backscatter from nadir observations provided by Jason-1 altimeter in both Ku- and C-band. A small but clear wind direction signal for wind speeds above 6 m/s is revealed. These azimuthal variations of radar cross-section increase with increasing wind speed up to 14 m/s. The signatures then level off at higher winds. These results extend, for the first time, recent theoretical improved scattering approximation, and point some similarities between scattering and emission mechanisms at nadir. The observed directional effect can thus be interpreted as a signature of the curvature anisotropy of wind-generated short-scale waves. Sensitivities to both wind speed and sea...
Tipo: Text Palavras-chave: Altimeter; Radar cross section; Polarization; Wind direction; Sea state.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/00004/11557/8150.pdf
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Comments on "A Combined Derivation of the Integrated and Vertically Resolved, Coupled Wave-Current Equations" ArchiMer
Ardhuin, Fabrice; Suzuki, Nobuhiro; Mcwilliams, James C.; Aiki, Hidenori.
Several equivalent equations for the evolution of the wave-averaged current momentum have been proposed, implemented, and used. In contrast, the equation for the total momentum, which is the sum of the current and wave momenta, has not been widely used because it requires a less practical wave forcing. In an update on previous derivations, Mellor proposed a new formulation of the wave forcing for the total momentum equation. Here, the authors show that this derivation misses a leading-order term that has a zero depth-integrated value. Corrected for this omission, the wave forcing is equivalent to that in the first paper by Mellor. When this wave forcing effect on the currents is approximated it leads to an inconsistency. This study finally repeats and...
Tipo: Text Palavras-chave: Currents; Mixed layer; Sea state.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00406/51733/52298.pdf
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Ecology and taxonomy of free-living marine nematodes from Cienfuegos bay, Caribbean sea OceanDocs
Armenteros Almanza, M..
Present thesis focuses on ecology of assemblages and taxonomy of free-living marine nematodes. Most of the data are from Cienfuegos, a semi-enclosed bay in the Caribbean Sea; but, we also provided data on biodiversity from other areas in Cuban marine waters. Four main topics are included: description of biodiversity patterns, a microcosm experiment about effects of organic enrichment on assemblages, a taxonomic revision of the genus Terschellingia de Man, 1888, and the description of four new genera for science.
Tipo: Theses and Dissertations Palavras-chave: Ecology; Taxonomy; Marine water; Biodiversity; Sea state.
Ano: 2010 URL: http://hdl.handle.net/1834/5386
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Influence of the sea state on Mediterranean heavy precipitation: a case-study from HyMeX SOP1 ArchiMer
Thevenot, O.; Bouin, M. -n.; Ducrocq, V.; Brossier, C. Lebeaupin; Nuissier, O.; Pianezze, Joris; Duffourg, F..
Sea state can influence the turbulent air–sea exchanges, especially the momentum flux, by modifying the sea-surface roughness. The high-resolution non-hydrostatic convection-permitting model MESO-NH is used here to investigate the impact of a more realistic representation of the waves on heavy precipitation during the Intense Observation Period (IOP) 16a of the first HyMeX Special Observation Period (SOP1). Several quasi-stationary mesoscale convective systems developed over the western Mediterranean region, two of them over the sea, and resulted in heavy precipitation on the French and Italian coasts on 26 October 2012. Three different bulk parametrizations are tested in this study: a reference case (NOWAV) without any wave effect, a parametrization...
Tipo: Text Palavras-chave: Air-sea exchanges; Mediterranean Sea; HyMeX; MESO-NH; Sea state; Roughness length; Turbulent fluxes; Heavy precipitation.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00285/39639/41533.pdf
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Observing Sea States ArchiMer
Ardhuin, Fabrice; Stopa, Justin; Chapron, Bertrand; Collard, Fabrice; Husson, Romain; Jensen, Robert E.; Johannessen, Johnny; Mouche, Alexis; Passaro, Marcello; Quartly, Graham D.; Swail, Val; Young, Ian.
Sea state information is needed for many applications, ranging from safety at sea and on the coast, for which real time data are essential, to planning and design needs for infrastructure that require long time series. The definition of the wave climate and its possible evolution requires high resolution data, and knowledge on possible drift in the observing system. Sea state is also an important climate variable that enters in air-sea fluxes parameterizations. Finally, sea state patterns can reveal the intensity of storms and associated climate patterns at large scales, and the intensity of currents at small scales. A synthesis of user requirements leads to requests for spatial resolution at kilometer scales, and estimations of trends of a few centimeters...
Tipo: Text Palavras-chave: Sea state; Waves; Altimeter; SAR; Swell; Remote sensing; Buoy; Microseisms.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00489/60090/63432.pdf
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Refined sea state analysis from an array of four identical directional buoys deployed off the Northern Cornish coast (UK) ArchiMer
Saulnier, Jean Baptiste; Maisondieu, Christophe; Ashton, Ian; Smith, George H..
This paper presents an analysis of sea states carried out from extended wave measurements realized near the Wave Hub wave energy test facility in Cornwall (UK). The space directional information is derived from the spectro-directional processing of time-domain data provided by an array of four independent SEAWATCH Mini II displacement buoys separated by an approximate average distance of 500 m. It is observed that, even though the size of the array is small compared to the local wave trains' length, the estimation of the directional spectra - using maximum entropy and likelihood methods - may sometimes exhibit certain space variability over the array. It was also observed that the tidal currents variations produced a significant influence upon the wave...
Tipo: Text Palavras-chave: Directional wave spectrum; Directional buoys; Buoys array; Maximum entropy method; Maximum Likelihood Method; Sea state; Wave system; Spectro-directional partitioning; Wave stationarity/homogeneity; Wave/tide interactions.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00098/20922/18739.pdf
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Refinements of sea state statistics for marine renewables: A case study from simultaneous buoy measurements in Portugal ArchiMer
Saulnier, Jean Baptiste; Prevosto, Marc; Maisondieu, Christophe.
This paper presents a refined description of the wave climate observed in a Portuguese location for marine energy projects. The data used in this case study were derived from 3-month in situ measurements carried out using three directional buoys that have been deployed simultaneously – yet independently (various buoy types and water depths) – on the Atlantic coast in the neighbourhood of Figueira da Foz. Two ways of reporting the statistics were adopted. In the first one, each recorded sea state was summarized as a set of global parameters accounting for energy, mean frequency and direction, spectral bandwidth and directional spreading related to the main ongoing wave field considered as unimodal. In the second one, each sea state has been decomposed into...
Tipo: Text Palavras-chave: Sea state; Directional spectrum; Wave systems; Spectrum partitioning; Spectral bandwidth; Directional spreading.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00037/14813/12196.pdf
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SKIM, a Candidate Satellite Mission Exploring Global Ocean Currents and Waves ArchiMer
Ardhuin, Fabrice; Brandt, Peter; Gaultier, Lucile; Donlon, Craig; Battaglia, Alessandro; Boy, François; Casal, Tania; Chapron, Bertrand; Collard, Fabrice; Cravatte, Sophie; Delouis, Jean Marc; De Witte, Erik; Dibarboure, Gerald; Engen, Geir; Johnsen, Harald; Lique, Camille; Lopez-dekker, Paco; Maes, Christophe; Martin, Adrien; Marié, Louis; Menemenlis, Dimitris; Nouguier, Frederic; Peureux, Charles; Rampal, Pierre; Ressler, Gerhard; Rio, Marie-helene; Rommen, Bjorn; Shutler, Jamie D.; Suess, Martin; Tsamados, Michel; Ubelmann, Clement; Van Sebille, Erik; Van Den Oever, Martin; Stammer, Detlef.
The Sea surface KInematics Multiscale monitoring (SKIM) satellite mission is designed to explore ocean surface current and waves. This includes tropical currents, notably the poorly known patterns of divergence and their impact on the ocean heat budget, and monitoring of the emerging Arctic up to 82.5°N. SKIM will also make unprecedented direct measurements of strong currents, from boundary currents to the Antarctic circumpolar current, and their interaction with ocean waves with expected impacts on air-sea fluxes and extreme waves. For the first time, SKIM will directly measure the ocean surface current vector from space. The main instrument on SKIM is a Ka-band conically scanning, multi-beam Doppler radar altimeter/wave scatterometer that includes a...
Tipo: Text Palavras-chave: Ocean current; Tropics; Arctic; Doppler; Altimetry; Sea state; Remote sensing; Ocean waves.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00498/60964/64372.pdf
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Strong winds in a coupled wave-atmosphere model during a North Atlantic storm event: evaluation against observations ArchiMer
Pineau-guillou, Lucia; Ardhuin, Fabrice; Bouin, Marie-noelle; Redelsperger, Jean-luc; Chapron, Bertrand; Bidlot, Jean-raymond; Quilfen, Yves.
Strong winds may be biased in atmospheric models. Here the ECMWF coupled wave-atmosphere model is used (1) to evaluate strong winds against observations, (2) to test how alternative wind stress parameterizations could lead to a more accurate model. For the period of storms Kaat and Lilli (23 to 27 January 2014), we compared simulated winds with in-situ – moored buoys and platforms - and satellite observations available from the North Atlantic. Five wind stress parameterizations were evaluated. The first result is that moderate simulated winds (5-20 m s-1) match with all observations. However, for strong winds (above 20 m s-1), mean differences appear, as much as -7 m s-1 at 30 m s-1. Significant differences also exist between observations, with buoys and...
Tipo: Text Palavras-chave: Air-sea exchanges; Northeast Atlantic; Winds; IFS; Sea state; Roughness length; Drag coefficient; Wind stress.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00410/52118/52826.pdf
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Surface Roughness Imaging of Currents Shows Divergence and Strain in the Wind Direction ArchiMer
Rascle, Nicolas; Chapron, Bertrand; Ponte, Aurelien; Ardhuin, Fabrice; Klein, Patrice.
Images of sea surface roughness-for example, obtained by synthetic aperture radars (SAR) or by radiometers viewing areas in and around the sun glitter-at times provide clear observations of meso- and sub-mesoscale oceanic features. Interacting with the surface wind waves, particular deformation properties of surface currents are responsible for those manifestations. Ignoring other sources of surface roughness variations, the authors limit their discussion to the mean square slope (mss) variability. This study confirms that vortical currents and currents with shear in the wind direction shall not be expressed in surface roughness images. Only divergent currents or currents with no divergence but strained in the wind direction can exhibit surface roughness...
Tipo: Text Palavras-chave: Circulation/ Dynamics; Ageostrophic circulations; Atmosphere-ocean interaction; Mesoscale processes; Wind waves; Atm/Ocean Structure/ Phenomena; Boundary layer; Sea state.
Ano: 2014 URL: https://archimer.ifremer.fr/doc/00210/32170/30619.pdf
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Survey of stochastic models for wind and sea state time series ArchiMer
Monbet, Valérie; Ailliot, P; Prevosto, Marc.
The knowledge of sea state and wind conditions is of central importance for many offshore and nearshore operations. In this paper, we make a complete survey of stochastic models for sea state and wind time series. We begin with methods based on Gaussian processes, then non-parametric resampling methods for time series are introduced followed by various parametric models. We also propose an original statistical method, based on Monte Carlo goodness-of-fit tests, for model validation and comparison and this method is illustrated on an example of multivariate sea state time series. (C) 2006 Elsevier Ltd. All rights reserved.
Tipo: Text Palavras-chave: Model validation; Simulation; Nonlinear time series; Wind; Sea state.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2679.pdf
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