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Registros recuperados: 12
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A note on the direct injection of turbulence by breaking waves ArchiMer
Rascle, Nicolas; Chapron, Bertrand; Ardhuin, Fabrice; Soloviev, Alexander.
We investigate the turbulence induced by wave-breaking at the ocean surface. Two recent models use a mechanism of direct depth injection of turbulent kinetic energy (TKE) by breaking waves. Those models aim to reproduce the near-surface mean and turbulent properties, in particular the TKE dissipation rates. Of critical importance are the injection depth of each breaking wave and the size distribution of those breaking waves. The models by Sullivan et al. (2007) and by Kudryavtsev et al. (2008) have very different parameterizations, and those differences are reviewed here and compared to available observations. Using realistic parameterizations in these models leads to TKE injections too shallow to compare to observations, in particular for developed seas....
Tipo: Text Palavras-chave: Surface waves; Wave breaking; Wave-induced turbulence; Vertical mixing; Mixed layer; Ekman currents.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00155/26581/25476.pdf
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Chlorophyll profiles and the water column structure in the Gulf of California ArchiMer
Hidalgo-gonzalez, Raquel M; Alvarez-borrego, Saul.
Remote sensors provide information on the photosynthetic pigment concentration for the upper 22% of the euphotic zone. To model primary production in the water column from satellite-derived photosynthetic pigments, estimates of the vertical distribution of pigment concentration are required. A Gaussian distribution function is used to represent the pigment vertical profile with four parameters. We used 268 chlorophyll concentration profiles from 1973 through 1993, to estimate these parameters. Cluster analysis of surface temperature was used to define the cool season as the period end of November-end of June, and the rest of the year is considered the warm season. Cluster analysis of surface temperature acid chlorophyll data grouped the stations into four...
Tipo: Text Palavras-chave: Chlorophylle; Profil vertical; Golfe de Californie; Télédétection; Couche mélangée; Chlorophyll; Vertical profiles; Gulf of California; Remote sensing; Mixed layer.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/00322/43367/42848.pdf
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CIRENE Air-Sea Interactions in the Seychelles-Chagos Thermocline Ridge Region ArchiMer
Vialard, Jerome; Duvel, J. P.; Mcphaden, M. J.; Bouruet-aubertot, P.; Ward, Ben; Key, E.; Bourras, D.; Weller, Robert; Minnett, P.; Weill, A.; Cassou, C.; Eymard, L.; Fristedt, T.; Basdevant, C.; Dandonneau, Y.; Duteil, O.; Izumo, T.; De Boyer Montegut, Clement; Masson, S.; Marsac, F.; Menkes, C.; Kennan, S..
A field experiment in the southwestern Indian Ocean provides new insights into ocean-atmosphere interactions in a key climatic region.
Tipo: Text Palavras-chave: Madden julian oscillation; Southwest indian ocean; Surface temperature; Mixed layer; Intraseasonal variability; Rainfall variability; Tropical cyclones; Western pacific; Dipole mode; El nino.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00185/29634/27990.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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Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey ArchiMer
Caldeira, Rui M. A.; Stegner, Alexandre; Couvelard, Xavier; Araujo, Isabel B.; Testor, Pierre; Lorenzo, Alvaro.
Island wakes are areas of a strong eddy activity influencing the availability and transport of organic matter in the ocean which, in turn impact biological productivity. Despite this, eddy formation in the lee of North Atlantic tropical islands is scarcely documented, except for the Canary Islands. Moreover, the occurrence of anticyclones leeward of Madeira has seldom been detected. During the summer of 2011, a multiplatform approach, combining satellite data with in situ measurements, was used to study an anticyclonic eddy generated in the lee of the Madeira Island. The main objective was to confirm recent numerical evidence suggesting that orographically perturbed winds can induce anticyclonic eddies leeward of Madeira, particularly during summer months....
Tipo: Text Palavras-chave: Boundary-layer; Inertial instability; Mode water; Mixed layer; Intrathermocline eddies; Wake.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00197/30846/29209.pdf
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Indo-Pacific Sea surface temperature perturbations associated with intraseasonal oscillations of tropical convection ArchiMer
Duvel, Jean Philippe; Vialard, Jerome.
The intraseasonal variability (ISV; 20-90 days) of the SST is examined using 7 yr of data from the Tropical Rainfall Measuring Mission's (TRMM) Microwave Imager ( TMI). The ISV of the SST is larger in the summer hemisphere and in regions of relatively small ocean mixed layer depth (MLD). For these regions, the reddening of the SST spectrum in regard to the surface flux spectrum suggests that the ISV of the SST is mostly controlled by the integration of the local surface forcing by ocean mixed layer. However, the precise origin of large-scale organized perturbations of the SST also depends on region and season. Since the ISV of the convection is an intermittent phenomenon, the local mode analysis (LMA) technique is used to detect only the ensemble of...
Tipo: Text Palavras-chave: Madden julian oscillation; Western indian ocean; Summer monsoon; Mixed layer; Warm pool; Variability; Fluxes; Model; Atmosphere; Bengal.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00185/29638/27986.pdf
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Interannual variability of the Tropical Indian Ocean mixed layer depth ArchiMer
Keerthi, M. G.; Lengaigne, M.; Vialard, Jerome; De Boyer Montegut, Clement; Muraleedharan, P. M..
In the present study, interannual fluctuations of the mixed layer depth (MLD) in the tropical Indian Ocean are investigated from a long-term (1960-2007) eddy permitting numerical simulation and a new observational dataset built from hydrographic in situ data including Argo data (1969-2008). Both datasets show similar interannual variability patterns in relation with known climate modes and reasonable phase agreement in key regions. Due to the scarcity of the observational dataset, we then largely rely on the model to describe the interannual MLD variations in more detail. MLD interannual variability is two to four times smaller than the seasonal cycle. A large fraction of MLD interannual variations is linked to large-scale climate modes, with the exception...
Tipo: Text Palavras-chave: Mixed layer; Interannual variability; Indian Ocean; Indian Ocean Dipole; El Nino/Southern Oscillation; Monsoon.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00124/23564/22771.pdf
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Low and high frequency Madden-Julian oscillations in austral summer: interannual variations ArchiMer
Izumo, Takeshi; Masson, Sebastien; Vialard, Jerome; De Boyer Montegut, Clement; Behera, Swadhin K.; Madec, Gurvan; Takahashi, Keiko; Yamagata, Toshio.
The Madden-Julian oscillation (MJO) is the main component of intraseasonal variability of the tropical convection, with clear climatic impacts at an almost-global scale. Based on satellite observations, it is shown that there are two types of austral-summer MJO events (broadly defined as 30-120 days convective variability with eastward propagation of about 5 m/s). Equatorial MJO events have a period of 30-50 days and tend to be symmetric about the equator, whereas MJO events centered near 8A degrees S tend to have a longer period of 55-100 days. The lower-frequency variability is associated with a strong upper-ocean response, having a clear signature in both sea surface temperature and its diurnal cycle. These two MJO types have different interannual...
Tipo: Text Palavras-chave: Intraseasonal Madden-Julian oscillation (MJO); Seychelles-Chagos thermocline ridge/thermocline dome of the Indian Ocean; Indian Ocean dipole (IOD); El Nino southern oscillation (ENSO); Diurnal cycle; Oceanic diurnal warm layers; Air-sea interactions; Ocean-atmosphere coupling; Interannual variations; Mixed layer; Australian weather.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00013/12416/9221.pdf
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Observing mixed layer depth, nitrate and chlorophyll concentrations in the northwestern Mediterranean: A combined satellite and NO 3 profiling floats experiment ArchiMer
D'Ortenzio, Fabrizio; Lavigne, Heloise; Besson, Florent; Claustre, Herve; Coppola, Laurent; Garcia, Nicole; Laes-huon, Agathe; Le Reste, Serge; Malarde, Damien; Migon, Christophe; Morin, Pascal; Mortier, Laurent; Poteau, Antoine; Prieur, Louis; Raimbault, Patrick; Testor, Pierre.
Two profiling floats, equipped with nitrate concentration sensors were deployed in the northwestern Mediterranean from summer 2012 to summer 2013. Satellite ocean color data were extracted to evaluate surface chlorophyll concentration at float locations. Time series of mixed layer depths and nitrate and chlorophyll concentrations were analyzed to characterize the interplay between the physical-chemical and biological dynamics in the area. Deep convection (mixed layer depth > 1000 m) was observed in January–February, although high-nitrate surface concentrations could be already observed in December. Chlorophyll increase is observed since December, although high values were observed only in March. The early nitrate availability in subsurface layers, which...
Tipo: Text Palavras-chave: Bio-Argo; Mediterranean; Mixed layer; Bloom onset; Nitrate concentration; Ocean color satellite.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00211/32225/30673.pdf
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Synthesis of the POMME physical data set: One year monitoring of the upper layer ArchiMer
Gaillard, Fabienne; Mercier, Herle; Kermabon, Catherine.
The Programme Ocean Multidisciplinaire Meso Echelle (POMME) experiment was designed to describe and quantify the role of mesoscale processes in the subduction of mode waters in the northeast Atlantic. During 1 year ( September 2000 - October 2001), in situ measurements were conducted over a 8 degrees square area centered on 18 degrees W, 42 degrees N. We present the synthesis of the physical data set collected during this experiment. To improve time and space coverages, these measurements are combined with satellite information from sea surface temperature and altimetry. Daily fields of temperature, salinity, and stream function are produced over a seasonal cycle with a simplified Kalman filter. We analyze the annual cycle of the upper layer. The 1 year...
Tipo: Text Palavras-chave: Upper ocean seasonal cycle; Mesoscale; Northeast Atlantic; Subduction; Mode water; Mixed layer.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-455.pdf
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Variabilité de la salinité de surface d'après un modèle global de couche mélangée océanique ArchiMer
Michel, Sylvain.
Sea surface salinity (SSS) influences numerous oceanic phenomena, for instance surface water ventilation, deep water formation and thermohaline circulation. SSS also controls some ocean-atmosphere coupled processes, such as the intensity of freshwater flux and the penetration of heat flux and turbulence. Salinity is more difficult to measure than temperature from in situ surveys, which results in 20 times less data being currently available. Moreover, sea surface temperature (SST) is routinely estimated from satellites, which is not possible yet for SSS. Two space missions will fill this gap soon: SMOS from the European Space Agency and Aquarius/SAC-D from NASA and CONAE. To contribute to the SMOS project, we propose a method for estimating SSS from...
Tipo: Text Palavras-chave: SMOS; SSS; SST; MLD; Heat balance; Vertical entrainment; Geostrophic current; Air sea fluxes; Satellite observations; Mixed layer; Salinity; SMOS; SSS; SST; MLD; Bilan de chaleur; Entraînement vertical; Courants géostrophiques; Flux air mer; Observations satellitaires; Couche mélangée; Salinité.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/these-2302.pdf
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Variability of the Heat and Salt Budget in the Subtropical Southeastern Pacific Mixed Layer between 2004 and 2010: Spice Injection Mechanism ArchiMer
Kolodziejczyk, Nicolas; Gaillard, Fabienne.
The mixed layer heat and salt budget in the southeastern subtropical Pacific are estimated using 7 years (2004-10) of Argo-profiling float data, surface fluxes, precipitation, surface velocity data, and wind observations and reanalysis. In this region, the mixed layer heat budget is characterized by a strong annual cycle mainly modulated by the shortwave radiation annual cycle. During the austral fall and winter, the shortwave radiation input minimum is overwhelmed by the heat loss mainly because of the latent heat flux. The mixed layer salt budget also presents a strong annual cycle with a minimum of salt content during the late austral winter. In contrast with the heat budget, the salt budget is mainly driven by the unresolved terms computed as the...
Tipo: Text Palavras-chave: Mixed layer; Heat budgets; Fluxes; Salinity; In situ oceanic observations; Interannual variability; Seasonal cycle.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00155/26587/24722.pdf
Registros recuperados: 12
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