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| Registros recuperados: 15 | |
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| Gula, Jonathan; Molemaker, Maarten Jeroen; Mcwilliams, James C.. |
| Most of the ocean kinetic energy is contained in the large scale currents and the vigorous geostrophic eddy field, at horizontal scales of order 100 km. To achieve equilibrium the geostrophic currents must viscously dissipate their kinetic energy at much smaller scale. However, geostrophic turbulence is characterized by an inverse cascade of energy towards larger scale, and the pathways of energy toward dissipation are still in question. Here, we present a mechanism, in the context of the Gulf Stream, where energy is transferred from the geostrophic flow to submesoscale wakes through anticyclonic vertical vorticity generation in the bottom boundary layer. The submesoscale turbulence leads to elevated local dissipation and mixing outside the oceanic... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00357/46814/46679.pdf |
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| Klymak, Jody M.; Shearman, R. Kipp; Gula, Jonathan; Lee, Craig M.; D'Asaro, Eric A.; Thomas, Leif N.; Harcourt, Ramsey R.; Shcherbina, Andrey Y.; Sundermeyer, Miles A.; Molemaker, Jeroen; Mcwilliams, James C.. |
| The Gulf Stream is a major conduit of warm surface water from the tropics to the subpolar North Atlantic. Here we observe and simulate a submesoscale (<20km) mechanism by which the Gulf Stream exchanges water with subpolar water to the north. Along isopycnals, the front has a sharp compensated temperature-salinity contrast, with distinct mixed water between the two water masses 2 and 4km wide. This mixed water does not increase downstream despite substantial energy available for mixing. A series of streamers detrain this water at the crest of meanders. Subpolar water replaces the mixed water and resharpens the front. The water mass exchange accounts for a northward flux of salt of 0.5-2.5 psum(2)s(-1), (large-scale diffusivity O (100m(2)s(-1))). This is... |
| Tipo: Text |
Palavras-chave: Ocean mixing; Gulf Stream; Submesoscale mixing; Eddies. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00600/71201/69570.pdf |
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| Wenegrat, Jacob O.; Thomas, Leif N.; Gula, Jonathan; Mcwilliams, James C.. |
| Non-conservative processes change the potential vorticity (PV) of the upper ocean, and later, through the subduction of surface waters into the interior, affect the general ocean circulation. Here we focus on how boundary layer turbulence, in the presence of submesoscale horizontal buoyancy gradients, generates a source of potential vorticity at the ocean surface through a balance known as the Turbulent ThermalWind. This source of PV injection at the submesoscale can be of similar magnitude to PV fluxes from the wind and surface buoyancy fluxes, and hence can lead to a net injection of PV onto outcropped isopycnals even during periods of surface buoyancy loss. The significance of these dynamics is illustrated using a high-resolution realistic model of the... |
| Tipo: Text |
Palavras-chave: Ageostrophic circulations; Atmosphere-ocean interaction; Fronts; Ocean dynamics; Potential vorticity; Boundary layer. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00452/56347/57937.pdf |
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| Stevens, Bjorn; Bony, Sandrine; Farrell, David; Ament, Felix; Blyth, Alan M.; Fairall, Christopher W.; Karstensen, Johannes; Quinn, Patricia K.; Speich, Sabrina; Acquistapace, Claudia; Aemisegger, Franziska; Albright, Anna Lea; Bellenger, Hugo; Bodenschatz, Eberhard; Caesar, Kathy-ann; Chewitt-lucas, Rebecca; De Boer, Gijs; Delanoë, Julien; Denby, Leif Christopher; Ewald, Florian; Fildier, Benjamin; Forde, Marvin; George, Geet; Gross, Silke; Hagen, Martin; Hausold, Andrea; Heywood, Karen J.; Hirsch, Lutz; Jacob, Marek; Jansen, Friedhelm; Kinne, Stefan; Klocke, Daniel; Kölling, Tobias; Konow, Heike; Lothon, Marie; Mohr, Wiebke; Naumann, Ann Kristin; Nuijens, Louise; Olivier, Léa; Pincus, Robert; Pöhlker, Mira L.; Reverdin, Gilles; Roberts, Gregory; Schnitt, Sabrina; Schulz, Hauke; Siebesma, Pier; Stephan, Caroline; Sullivan, Peter P; Touzé-peiffer, Ludovic; Vial, Jessica; Vogel, Raphaela; Zuidema, Paquita; Alexander, Nicola; Alves, Lyndon; Arixi, Sophian; Asmath, Hamish; Bagheri, Gholamhossein; Baier, Katharina; Bailey, Adriana; Baranowski, Dariusz B.; Baron, Aurelie; Barrau, Sébastien; Barrett, Paul Alan; Batier, Frédéric; Behrendt, Andreas; Bendinger, Arne; Beucher, Florent; Bigorre, Sebastien; Blades, Edmund; Blossey, P; Bock, Olivier; Boeing, Steven J; Bosser, Pierre; Bourras, Denis; Bouruet-aubertot, Pascale; Bower, Keith; Branellec, Pierre; Branger, Hubert; Brennek, Michal; Brewer, Alan; Brilouet, Pierre Etienne; Brügmann, Björn; Buehler, Stefan Alexander; Burke, Elmo; Burton, Ralph; Calmer, Radiance; Canonici, Jean-christophe; Carton, Xavier; Cato, Gregory; Charles, Jude Andre; Chazette, Patrick; Chen, Yanxu; Chilinski, Michal T; Choularton, Tom; Chuang, Patrick Y.; Clarke, Shamal; Coe, Hugh; Cornet, Cas; Coutris, Pierre; Couvreux, Fleur; Crewell, Susanne; Cronin, Timothy Wallace; Cui, Zhiqiang; Cuypers, Yannis; Daley, Alton; Damerell, Gillian Mary; Dauhut, Thibaut; Deneke, Hartwig M; Desbios, Jean-philippe; Dörner, Steffen; Donner, Sebastian; Douet, Vincent; Drushka, Kyla; Dütsch, Marina; Ehrlich, André; Emanual, Kerry; Emmanouilidis, Alexandros; Etienne, Jean-claude; Etienne-leblanc, Sheryl; Faure, Ghislain; Feingold, Graham; Ferrero, Luca; Fix, Andreas; Flamant, Cyrille; Flatau, Piotr J.; Foltz, Gregory R.; Forster, Linda; Furtuna, Iulian; Gadian, Alan; Galewsky, Joseph; Gallagher, Martin; Gallimore, Peter; Gaston, Cassandra J.; Gentemann, Chelle; Geyskens, Nicolas; Giez, Andreas; Gollop, John; Gouirand, Isabelle; Gourbeyre, Christophe; De Graaf, Dörte; De Groot, Geiske E.; Grosz, Robert; Güttler, Johannes; Gutleben, Manuel; Hall, Kashawn; Harris, George; Helfer, Kevin Christopher; Henze, Dean; Herbert, Calvert; Holanda, Bruna; Ibanez-landeta, Antonio; Intrieri, Janet M.; Iyer, Suneil; Julien, Fabrice; Kalesse, Heike; Kazil, Jan; Kellman, Alexander; Kidane, Abiel T.; Kirchner, Ulrike; Klingebiel, Marcus; Körner, Mareike; Kremper, Leslie Ann; Kretzschmar, Jan; Krüger, Ovid; Kumala, Wojciech; Kurz, Armin; L'Hégaret, Pierre; Labaste, Matthieu; Lachlan-cope, Tom A.; Laing, Arlene; Landschützer, Peter; Lang, Theresa; Lange Vega, Diego; Lange, Ingo; Laplace, Clément; Lavik, Gaute; Laxenaire, Rémi; Le Bihan, Caroline; Leandro, Mason; Lefèvre, Nathalie; Lena, Marius; Leschow, Donald; Li, Qiang; Lloyd, Gary; Los, Sebastian; Losi, Niccolò; Lovell, Oscar; Luneau, Christopher; Makuch, Przemyslaw; Malinowski, Szymon P; Manta, Gaston; Marinou, Eleni; Marsden, Nicholas; Masson, Sebastien; Maury, Nicolas; Mayer, Bernhard; Mayers-als, Margarette; Mazel, Christophe; Mcgeary, Wayne; Mcwilliams, James C.; Mech, Mario; Mehlmann, Melina; Meroni, Agostino Niyonkuru; Mieslinger, Theresa; Minikin, Andreas; Minnett, Peter; Möller, Gregor; Morfa Avalos, Yanmichel; Muller, Caroline; Musat, Ionela; Napoli, Anna; Neuberger, Almuth; Noisel, Christophe; Noone, David C; Nordsiek, Freja; Nowak, Jakub L; Oswald, Lothar; Parker, Douglas J.; Peck, Carolyn; Person, Roland; Philippi, Miriam; Plueddemann, Albert J.; Pöhlker, Christopher; Pörtge, Veronika; Pöschl, Ulrich; Pologne, Lawrence; Posyniak, Michal; Prange, Marc; Quiñones Meléndez, Estefanía; Radtke, Jule; Ramage, Karim; Reimann, Jens; Renault, Lionel; Reus, Klaus; Reyes, Ashford; Ribbe, Joachim; Ringel, Maximilian; Ritschel, Markus; Rocha, Cesar Barbedo; Rochetin, Nicolas; Röttenbacher, Johannes; Rollo, Callum; Royer, Haley; Sadoulet, Pauline; Saffin, Leo; Sandiford, Sanola; Sandu, Irina; Schäfer, Michael; Schemann, Vera; Schirmacher, Imke; Schlenczek, Oliver; Schmidt, Jerome; Schröder, Marcel; Schwarzenboeck, Alfons; Sealy, Andrea; Senff, Christoph J; Serikov, Ilya; Shohan, Samkeyat; Siddle, Elizabeth; Smirnov, Alexander; Späth, Florian; Spooner, Branden; Stolla, M. Katharina; Szkólka, Wojciech; De Szoeke, Simon P.; Tarot, Stephane; Tetoni, Eleni; Thompson, Elizabeth J; Thomson, Jim; Tomassini, Lorenzo; Totems, Julien; Ubele, Alma Anna; Villiger, Leonie; Von Arx, Jan; Wagner, Thomas; Walther, Andi; Webber, Benjamin G. M.; Wendisch, Manfred; Whitehall, Shanice; Wiltshire, Anton; Wing, Allison A.; Wirth, Martin; Wiskandt, Jonathan; Wolf, Kevin; Worbes, Ludwig; Wright, Ethan; Wulfmeyer, Volker; Young, Shanea; Zhang, Cong; Zhang, Dongxiao; Ziemen, Florian; Zinner, Tobias; Zöger, Martin. |
| The science guiding the \EURECA campaign and its measurements are presented. \EURECA comprised roughly five weeks of measurements in the downstream winter trades of the North Atlantic — eastward and south-eastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, \EURECA marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or, or the life-cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso (200 km) and larger (500 km) scales, roughly four hundred... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77410/79070.pdf |
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| Kurian, Jaison; Colas, Francois; Capet, Xavier; Mcwilliams, James C.; Chelton, Dudley B.. |
| Eddy detection and tracking algorithms are applied to both satellite altimetry and a high-resolution (dx = 5 km) climatological model solution of the U.S. West Coast to study the properties of surface and undercurrent eddies in the California Current System. Eddy properties show remarkable similarity in space and time, and even somewhat in polarity. Summer and fall are the most active seasons for undercurrent eddy generation, while there is less seasonal variation at surface. Most of the eddies have radii in the range of 25-100 km, sea level anomaly amplitudes of 1-4 cm, and vorticity normalized by f amplitudes of 0.025-0.2. Many of the eddies formed near the coast travel considerable distance westward with speeds about 2 km/day, consistent with the beta... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00044/15484/12873.pdf |
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| Colas, Francois; Mcwilliams, James C.; Capet, Xavier; Kurian, Jaison. |
| The Peru-Chile current System (PCS) is a region of persistent biases in global climate models. It has strong coastal upwelling, alongshore boundary currents, and mesoscale eddies. These oceanic phenomena provide essential heat transport to maintain a cool oceanic surface underneath the prevalent atmospheric stratus cloud deck, through a combination of mean circulation and eddy flux. We demonstrate these behaviors in a regional, quasi-equilibrium oceanic model that adequately resolves the mesoscale eddies with climatological forcing. The key result is that the atmospheric heating is large (> 50 W m(-2)) over a substantial strip > 500 km wide off the coast of Peru, and the balancing lateral oceanic flux is much larger than provided by the offshore... |
| Tipo: Text |
Palavras-chave: Regional modelling; South-East Pacific; Heat Balance; Oceanic eddies; Regional climate. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19892/17756.pdf |
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| Renault, Lionel; Mcwilliams, James C.; Penven, Pierrick. |
| Coupled ocean-atmosphere simulations are carried out for the Mozambique Channel, the Agulhas Current System, and the Benguela Upwelling System to assess the ocean surface current feedback to the atmosphere and its impact on the Agulhas Current (AC) retroflection and leakage. Consistent with previous studies, we show that the current feedback slows down the oceanic mean circulation and acts as an oceanic eddy killer by modulating the energy transfer between the atmosphere and the ocean, reducing by 25% the mesoscale energy and inducing a pathway of energy transfer from the ocean to the atmosphere. The current feedback, by dampening the Eddy Kinetic Energy (EKE), shifts westward the distribution of the AC retroflection location, reducing the presence of... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00389/50077/50670.pdf |
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| Mcwilliams, James C.; Gula, Jonathan; Molemaker, Maarten Jeroen. |
| Eastward zonal jets are common in the ocean and atmosphere, for example, the Gulf Stream and jet stream. They are characterized by atypically strong horizontal velocity, baroclinic vertical structure with an upward flow intensification, large change in the density stratification meridionally across the jet, large-scale meanders around a central latitude, narrow troughs and broad crests, and a sharp and vertically sloping northern (poleward) "wall" defined by horizontal maxima in the lateral gradients of both velocity and density. Measurements and realistic oceanic simulations show these features in the Gulf Stream downstream from its western boundary separation point. A diagnostic theory based on the conservative balance equations is developed to calculate... |
| Tipo: Text |
Palavras-chave: Ageostrophic circulations; Frontogenesis/frontolysis; Ocean models. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00486/59786/62925.pdf |
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| Renault, Lionel; Mcwilliams, James C.; Gula, Jonathan. |
| Oceanic submesoscale currents (SMCs) occur on an scale of 0.1-10 km horizontally and have a large influence on the oceanic variability and on ecosystems. At the mesoscale (10-250 km), oceanic thermal and current feedbacks are known to have a significant influence on the atmosphere and on oceanic dynamics. However, air-sea interactions at the submesoscale are not well known because the small size of SMCs presents observational and simulation barriers. Using high-resolution coupled oceanic and atmospheric models for the Central California region during the upwelling season, we show that the current feedback acting through the surface stress dominates the thermal feedback effect on the ocean and dampens the SMC variability by approximate to 17% +/- 4%. As for... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00456/56804/58672.pdf |
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| 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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| Renault, Lionel; Molemaker, Maarten Jeroen; Gula, Jonathan; Masson, Sebastien; Mcwilliams, James C.. |
| The Gulf Stream (GS) is known to have a strong influence on climate, for example, by transporting heat from the tropics to higher latitudes. Although the GS transport intensity presents a clear interannual variability, satellite observations reveal its mean path is stable. Numerical models can simulate some characteristics of the mean GS path, but persistent biases keep the GS separation and postseparation unstable and therefore unrealistic. This study investigates how the integration of ocean surface currents into the ocean–atmosphere coupling interface of numerical models impacts the GS. The authors show for the first time that the current feedback, through its eddy killing effect, stabilizes the GS separation and postseparation, resolving long-lasting... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00358/46879/46760.pdf |
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| Solodoch, Aviv; Mcwilliams, James C.; Stewart, Andrew L.; Gula, Jonathan; Renault, Lionel. |
| The southward flowing deep limb of the Atlantic Meridional Overturning Circulation is comprised of both the Deep Western Boundary Current (DWBC) and interior pathways. The latter are fed by “leakiness” from the DWBC in the Newfoundland Basin. However, the cause of this leakiness has not yet been explored mechanistically. Here the statistics and dynamics of the DWBC leakiness in the Newfoundland Basin are explored using two float data sets and a high-resolution numerical model. The float leakiness around Flemish Cap is found to be concentrated in several areas (“hotspots”) that are collocated with bathymetric curvature and steepening. Numerical particle advection experiments reveal that the Lagrangian mean velocity is offshore at these hotspots, while... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00630/74184/73787.pdf |
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| Wang, Peng; Mcwilliams, James C.; Menesguen, Claire. |
| The linear instability of several rotating, stably stratified, interior vertical shear flows (U) over bar (z) is calculated in Boussinesq equations. Two types of baroclinic, ageostrophic instability, AI1 and AI2, are found in odd-symmetric (U) over bar (z) for intermediate Rossby number (R-0). AI1 has zero frequency; it appears in a continuous transformation of the unstable mode properties between classic baroclinic instability (BCI) and centrifugal instability (CI). It begins to occur at intermediate R-0 values and horizontal wavenumbers (k, l) that are far from l = 0 or k = 0, where the growth rate of BCI or CI is the strongest. AI1 grows by drawing kinetic energy from the mean flow, and the perturbation converts kinetic energy to potential energy. The... |
| Tipo: Text |
Palavras-chave: Baroclinic flows; Instability; Waves in rotating fluids. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00211/32230/30753.pdf |
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| Teles-machado, Ana; Peliz, Alvaro; Mcwilliams, James C.; Couvelard, Xavier; Ambar, Isabel. |
| We describe the seasonal cycle of the alongshore flows on the Northwestern Iberian Margin and explain what are the important mechanisms forcing the system. We used a 20-year model simulation at 2.3 km horizontal resolution, with realistic atmospheric forcing and covering the whole Western Iberian Margin. The model results are compared with satellite data, with data measured at two moored buoys and with a compilation of current meter data available for the study region. We show that currents over the slope are divided in three different cores: the Iberian Poleward Current (IPC) occupying the top 350 m, a deeper core at Mediterranean Water levels (∼600–1200 m) and in between the two, an equatorward core centered just beneath the IPC core, the Upper Slope... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00270/38112/42274.pdf |
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| Registros recuperados: 15 | |
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