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Registros recuperados: 11
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Global estimates of the energy transfer from the wind to the ocean, with emphasis on near‐inertial oscillations ArchiMer
Flexas, M. Mar; Thompson, Andrew F.; Torres, Hector S.; Klein, Patrice; Farrar, J. Thomas; Zhang, Hong; Menemenlis, Dimitris.
Estimates of the kinetic energy transfer from the wind to the ocean are often limited by the spatial and temporal resolution of surface currents and surface winds. Here, we examine the wind work in a pair of global, very high‐resolution (1/48° and 1/24° ), MITgcm simulations in Latitude‐Longitude‐Cap configuration (LLC) that provide hourly output at spatial resolutions of a few kilometers and include tidal forcing. A cospectrum analysis of wind stress and ocean surface currents shows positive contribution at large scales (>300 km) and near‐inertial frequency, and negative contribution from mesoscales, tidal frequencies and internal gravity waves (IGWs). Larger surface kinetic energy fluxes are in the Kuroshio in winter at large scales (40 mW m−2) and...
Tipo: Text Palavras-chave: Surface fluxes; Inertial oscillations; Wind power; Kinetic energy budget; Global ocean model; MITgcm.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00509/62058/66232.pdf
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Measuring currents, ice drift, and waves from space: the Sea surface KInematics Multiscale monitoring (SKIM) concept ArchiMer
Ardhuin, Fabrice; Aksenov, Yevgueny; Benetazzo, Alvise; Bertino, Laurent; Brandt, Peter; Caubet, Eric; Chapron, Bertrand; Collard, Fabrice; Cravatte, Sophie; Delouis, Jean Marc; Dias, Frederic; Dibarboure, Gerald; Gaultier, Lucile; Johannessen, Johnny; Korosov, Anton; Manucharyan, Georgy; Menemenlis, Dimitris; Menendez, Melisa; Monnier, Goulven; Mouche, Alexis; Nouguier, Frederic; Nurser, George; Rampal, Pierre; Reniers, Ad; Rodriguez, Ernesto; Stopa, Justin; Tison, Celine; Ubelmann, Clement; Van Sebille, Erik; Xie, Jiping.
We propose a satellite mission that uses a near-nadir Ka-band Doppler radar to measure surface currents, ice drift and ocean waves at spatial scales of 40 km and more, with snapshots at least every day for latitudes 75 to 82 degrees, and every few days for other latitudes. The use of incidence angles of 6 and 12 degrees allows for measurement of the directional wave spectrum, which yields accurate corrections of the wave-induced bias in the current measurements. The instrument's design, an algorithm for current vector retrieval and the expected mission performance are presented here. The instrument proposed can reveal features of tropical ocean and marginal ice zone (MIZ) dynamics that are inaccessible to other measurement systems, and providing global...
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Ano: 2018 URL: http://archimer.ifremer.fr/doc/00442/55318/56843.pdf
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Ocean Scale Interactions from Space ArchiMer
Klein, Patrice; Lapeyre, Guillaume; Siegelman, Lia; Qiu, Bo; Fu, Lee‐lueng; Torres, Hector; Su, Zhan; Menemenlis, Dimitris; Le Gentil, Sylvie.
Satellite observations of the last two decades have led to a major breakthrough emphasizing the existence of a strongly energetic mesoscale turbulent eddy field in all the oceans. This ocean mesoscale turbulence (OMT) is characterized by cyclonic and anticyclonic eddies (with a 100‐‐300 km size and depth scales of ~500‐‐1000 m) that capture approximatively 80% of the total kinetic energy and is now known to significantly impact the large‐scale ocean circulation, the ocean's carbon storage, the air‐sea interactions and therefore the Earth climate as a whole. However, OMT revealed by satellite observations has properties that differ from those related to classical geostrophic turbulence theories. In the last decade, a large number of theoretical and...
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Ano: 2019 URL: https://archimer.ifremer.fr/doc/00488/59951/63202.pdf
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Ocean submesoscales as a key component of the global heat budget ArchiMer
Su, Zhan; Wang, Jinbo; Klein, Patrice; Thompson, Andrew F.; Menemenlis, Dimitris.
Recent studies highlight that oceanic motions associated with horizontal scales smaller than 50 km, defined here as submesoscales, lead to anomalous vertical heat fluxes from colder to warmer waters. This unique transport property is not captured in climate models that have insufficient resolution to simulate these submesoscale dynamics. Here, we use an ocean model with an unprecedented resolution that, for the first time, globally resolves submesoscale heat transport. Upper-ocean submesoscale turbulence produces a systematicallyupward heat transport that is five times larger than mesoscale heat transport, with wintertime averages up to 100 W/m2 for mid-latitudes. Compared to a lower-resolution model, submesoscale heat transport warms the sea surface up to...
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Ano: 2018 URL: https://archimer.ifremer.fr/doc/00449/56019/57535.pdf
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Partitioning ocean motions into balanced motions and internal gravity waves: A modeling study in anticipation of future space missions ArchiMer
Torres, Hector S.; Klein, Patrice; Menemenlis, Dimitris; Qiu, Bo; Su, Zhan; Wang, Jinbo; Chen, Shuiming; Fu, Lee-lueng.
Internal gravity waves (IGWs) and balanced motions (BMs) with scales < 100‐km capture most of the vertical velocity field in the upper ocean. They have, however, different impacts on the ocean energy budget, which explains the need to partition motions into BMs and IGWs. One way is to exploit the synergy of using different satellite observations, the only observations with global coverage and a reasonable spatial and temporal resolution. But we need first to characterize and understand their signatures on the different surface oceanic fields. This study addresses this issue by using an ocean global numerical simulation with high‐resolution (1/48o). Our methodology is based on the analysis of the 12,000 frequency‐wavenumber spectra to discriminate these...
Tipo: Text Palavras-chave: Oceanic surface motions; Satellite observations; Balanced motions; Internal gravity waves.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00464/57568/59746.pdf
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Pathways of ocean heat towards Pine Island and Thwaites grounding lines ArchiMer
Nakayama, Yoshihiro; Manucharyan, Georgy; Zhang, Hong; Dutrieux, Pierre; Torres, Hector S.; Klein, Patrice; Seroussi, Helene; Schodlok, Michael; Rignot, Eric; Menemenlis, Dimitris.
In the Amundsen Sea, modified Circumpolar Deep Water (mCDW) intrudes into ice shelf cavities, causing high ice shelf melting near the ice sheet grounding lines, accelerating ice flow, and controlling the pace of future Antarctic contributions to global sea level. The pathways of mCDW towards grounding lines are crucial as they directly control the heat reaching the ice. A realistic representation of mCDW circulation, however, remains challenging due to the sparsity of in-situ observations and the difficulty of ocean models to reproduce the available observations. In this study, we use an unprecedentedly high-resolution (200 m horizontal and 10 m vertical grid spacing) ocean model that resolves shelf-sea and sub-ice-shelf environments in qualitative...
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Ano: 2019 URL: https://archimer.ifremer.fr/doc/00593/70560/68742.pdf
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Reconstructing Upper Ocean Vertical Velocity Field from Sea Surface Height in the Presence of Unbalanced Motion ArchiMer
Qiu, Bo; Chen, Shuiming; Klein, Patrice; Torres, Hector; Wang, Jinbo; Fu, Lee-lueng; Menemenlis, Dimitris.
Reconstructability of upper ocean vertical velocity (w) and vorticity (ζ) fields from high-resolution sea surface height (SSH) data is explored using the global 1/48° horizontal-resolution MITgcm output in the context of the forth-coming Surface Water and Ocean Topography (SWOT) mission. By decomposing w with an omega equation of the primitive-equation system and by taking into account the measurement design of the SWOT mission, this study seeks to reconstruct the subinertial, balanced w and ζ signals. By adopting the effective surface quasi-geostrophic (eSQG) framework and applying to the Kuroshio Extension region of the North Pacific, we find that the target and reconstructed fields have a spatial correlation of ~0.7 below the mixed layer for w and 0.7 ~...
Tipo: Text Palavras-chave: Eddies; Mesoscale processes; Ocean dynamics; Vertical motion; Altimetry.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00593/70561/68744.pdf
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Seasonality in Transition Scale from Balanced to Unbalanced Motions in the World Ocean ArchiMer
Qiu, Bo; Chen, Shuiming; Klein, Patrice; Wang, Jinbo; Torres, Hector; Fu, Lee-lueng; Menemenlis, Dimitris.
The transition scale Lt from balanced geostrophic motions to unbalanced wave motions, including near-inertial flows, internal tides and inertia-gravity wave continuum, is explored using the output from a global 1/48° horizontal resolution MITgcm simulation. Defined as the wavelength with equal balanced and unbalanced motion kinetic energy (KE) spectral density, Lt is detected to be geographically highly inhomogeneous: it falls below 40 km in the western boundary current and Antarctic Circumpolar Current regions, increases to 40- 100 km in the interior subtropical and subpolar gyres, and exceeds, in general, 200 km in the tropical oceans. With the exception of the Pacific and Indian sectors of the Southern Ocean, the seasonal KE uctuations of the surface...
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Ano: 2018 URL: https://archimer.ifremer.fr/doc/00423/53431/54318.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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Small-scale open-ocean currents have large effects on wind-wave heights ArchiMer
Ardhuin, Fabrice; Gille, Sarah T.; Menemenlis, Dimitris; Rocha, Cesar B.; Rascle, Nicolas; Chapron, Bertrand; Gula, Jonathan; Molemaker, Jeroen.
Tidal currents and large-scale oceanic currents are known to modify ocean wave properties, causing extreme sea states that are a hazard to navigation. Recent advances in the understanding and modeling capability of open ocean currents have revealed the ubiquitous presence of eddies, fronts and filaments at scales 10 to 100∼km. Based on realistic numerical models, we show that these structures can be the main source of variability in significant wave heights at scales less than 200 km, including important variations down to 10 km. Model results are consistent with wave height variations along satellite altimeter tracks, resolved at scales larger than 50 km. The spectrum of significant wave heights is found to be of the order of 70〈Hs〉2/(g2〈Tm0,-1〉2) times...
Tipo: Text
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00382/49328/49708.pdf
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Surface Kinetic Energy Distributions in the Global Oceans From a High‐Resolution Numerical Model and Surface Drifter Observations ArchiMer
Yu, Xiaolong; Ponte, Aurelien; Elipot, Shane; Menemenlis, Dimitris; Zaron, Edward D.; Abernathey, Ryan.
The surface kinetic energy of a 1/48° global ocean simulation and its distribution as a function of frequency and location are compared with the one estimated from 15,329 globally distributed surface drifter observations at hourly resolution. These distributions follow similar patterns with a dominant low‐frequency component and well‐defined tidal and near‐inertial peaks globally. Quantitative differences are identified with deficits of low‐frequency energy near the equator (factor 2) and at near‐inertial frequencies (factor 3) and an excess of energy at semidiurnal frequencies (factor 4) for the model. Owing to its hourly resolution and its near‐global spatial coverage, the array of surface drifters is an invaluable tool to evaluate the realism of...
Tipo: Text Palavras-chave: LLC4320; Surface drifter; Rotary spectrum; SWOT.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00514/62517/66817.pdf
Registros recuperados: 11
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