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Registros recuperados: 12
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Circulation around La Reunion and Mauritius islands in the south-western Indian Ocean: A modeling perspective ArchiMer
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
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Dynamique de bord ouest en mer d'Arabie ArchiMer
Vic, Clement.
This PhD aims to investigate some western boundary processes in the Arabian Sea : (i) the life cycle of the socalled Great Whirl, a persistent mesoscale eddy; (ii) the dynamics of the Persian Gulf outflow, a marginal sea dense outflow; and (iii) the seasonal Oman upwelling, a coastal upwelling forced by summermonsoonal winds. The cornerstone of all these phenomena is their locationat a western boundary, which makes then being influenced by both localforcing (e.g., monsoonal winds) and remote forcing (Rossby waves and wesward drifting eddies). Specifically, the later are expected to impact the western boundary dynamics since the low latitude of the Arabian Sea implies a fast westward propagation of long Rossby waves and eddies. Moreover, waves are...
Tipo: Text Palavras-chave: Mer d'Arabie; Outfow; Golfe d'Oman; Golfe Persique; Ondes de Rossby; Upwelling; Dynamique de mésoéchelle et sous-mésoéchelle; Modélisation réaliste; Interactions tourbillon-topographie; Ocean modelling; Mesoscale and submesoscale dynamics; Arabian Sea; Great Whirl; Outflow; Gulf of Oman; Persian Gulf; Rossby waves; Eddy-topography interactions.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00498/60934/64328.pdf
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Flow variability near the Cape Verde frontal zone (subtropical Atlantic Ocean) ArchiMer
Vangriesheim, Annick; Bournot-marec, Claudie; Fontan, Anne-claire.
During the JGOFS-France/Eumeli programme, biogeochemical processes governing particle fluxes throughout the water column were studied in the Eastern Subtropical North Atlantic Ocean. From February 1991 to December 1992, three consecutive sets of sediment trap moorings were installed at two sites: the mesotrophic site: similar to18degrees 30 N, 21degrees 00 W, and the oligotrophic site: similar to21degrees 00 N, 31degrees 00 W. Currents were measured at each sediment trap level (250, 1000 and 2500 m) in order to understand better the dynamics in this area and its influence on the particle fluxes through the water column and to monitor the current speed conditions during the particle trapping. The results of these current measurements are presented here,...
Tipo: Text Palavras-chave: Rossby waves; Current variability; Cape Verde frontal zone; Eastern subtropical; North Atlantic ocean; Ondes de Rossby; Courant variabilité; Cap Vert; Subtropical Est; Océan Atlantique Nord.
Ano: 2003 URL: http://archimer.ifremer.fr/doc/2003/publication-374.pdf
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Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS ArchiMer
Vic, Clement; Roullet, Guillaume; Carton, Xavier; Capet, X..
The Great Whirl (GW) is a persistent anticyclonic mesoscale eddy that is observed seasonally in the Arabian Sea during a period embedding the 3 months of the southwest monsoon (June–July–August) at a quasi-steady location. Its dynamics remain unclear despite it being one of the largest coherent vortices in the world ocean. Realistic regional numerical experiments using ROMS are performed to investigate the life cycle of the GW, which is not well resolved by sparse available in situ measurements in the region. Using a set of sensitivity experiments and an accurate temporal characterization of the eddy properties (including position, radius, depth, and vorticity) we (i) confirm the role of basin-scale downwelling Rossby waves in the GW generation, (ii)...
Tipo: Text Palavras-chave: Arabian Sea; Indian Ocean; Great Whirl; Mesoscale dynamics; ROMS; Rossby waves.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00211/32197/30631.pdf
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Multidecadal variability of the overturning circulation in presence of eddy turbulence ArchiMer
Huck, Thierry; Arzel, Olivier; Sevellec, Florian.
At low-resolution, idealized ocean circulation models forced by prescribed differential surface heat fluxes show spontaneous multidecadal variability depending critically on eddy diffusivity coefficients. The existence of this critical threshold in the range of observational estimates legitimates some doubt on the relevance of such intrinsic oscillations in the real ocean. Through a series of numerical simulations with increasing resolution up to eddy-resolving ones (10 km) and various diapycnal diffusivities, this multidecadal variability proves a generic ubiquitous feature, at least in model versions with a flat bottom. The mean circulation largely changes in the process of refining the horizontal grid (along with the associated implicit viscosity and...
Tipo: Text Palavras-chave: Circulation/ Dynamics; Meridional overturning circulation; Rossby waves; Turbulence; Variability; Multidecadal variability.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00251/36243/34798.pdf
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Oceanic control of multidecadal variability in an idealized coupled GCM ArchiMer
Jamet, Quentin; Huck, Thierry; Arzel, Olivier; Campin, Jean-michel; De Verdiere, Alain Colin.
Idealized ocean models are known to develop intrinsic multidecadal oscillations of the meridional overturning circulation (MOC). Here we explore the role of ocean–atmosphere interactions on this low-frequency variability. We use a coupled ocean–atmosphere model set up in a flat-bottom aquaplanet geometry with two meridional boundaries. The model is run at three different horizontal resolutions (4°, 2° and 1°) in both the ocean and atmosphere. At all resolutions, the MOC exhibits spontaneous variability on multidecadal timescales in the range 30–40 years, associated with the propagation of large-scale baroclinic Rossby waves across the Atlantic-like basin. The unstable region of growth of these waves through the long wave limit of baroclinic instability...
Tipo: Text Palavras-chave: Atlantic multidecadal oscillation; Air-sea interactions; NAO; Rossby waves; Idealized configuration.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00334/44483/44197.pdf
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Satellite altimetry and ocean dynamics ArchiMer
Fu, Lee Lueng; Le Traon, Pierre-yves.
This paper provides a summary of recent results derived from satellite altimetry. It is focused on altimetry and ocean dynamics with synergistic use of other remote sensing techniques, in-situ data and integration aspects through data assimilation. Topics include mean ocean circulation and geoid issues, tropical dynamics and large-scale sea level and ocean circulation variability, high-frequency and intraseasonal variability, Rossby waves and mesoscale variability.
Tipo: Text Palavras-chave: Rossby waves; Large scale; Mesoscale; Sea level; Ocean dynamics; Satellite altimetry; Ondes de Rossby; Grande échelle; Mésoéchelle; Niveau de la mer; Dynamique de l'océan; Altimétrie satellitaire.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-2175.pdf
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Seasonal and intraseasonal biogeochemical variability in the thermocline ridge of the southern tropical Indian Ocean ArchiMer
Resplandy, L.; Vialard, Jerome; Levy, M.; Aumont, Olivier; Dandonneau, Y..
The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) time series shows high variability of surface chlorophyll at seasonal and intraseasonal time scales in the oligotrophic southern tropical Indian Ocean thermocline ridge called the Seychelles-Chagos thermocline ridge (SCTR). The SCTR is characterized by an open ocean upwelling due to local Ekman pumping, which annually maintains the mixed layer (ML) shallow and is responsive to atmospheric forcing and in particular to the Madden-Julian Oscillation (MJO) at an intraseasonal time scale. Here we present an overview of SCTR biogeochemistry and investigate the physical processes driving the response observed at seasonal and intraseasonal time scales. Using satellite observations and biophysical ocean...
Tipo: Text Palavras-chave: Madden julian oscillation; Arabian sea; Rossby waves; Interannual variability; Circulation model; Monsoon; Temperature; Perturbations; Nutrients; Dynamics.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00185/29630/27994.pdf
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Seasonal phasing of Agulhas Current transport tied to a baroclinic adjustment of near-field winds ArchiMer
Hutchinson, Katherine; Beal, Lisa M.; Penven, Pierrick; Ansorge, Isabelle; Hermes, Juliet.
The Agulhas Current plays a significant role in both local and global ocean circulation and climate regulation, yet the mechanisms that determine the seasonal cycle of the current remain unclear, with discrepancies between ocean models and observations. Observations from moorings across the current and a 22 year proxy of Agulhas Current volume transport reveal that the current is over 25% stronger in austral summer than in winter. We hypothesize that winds over the Southern Indian Ocean play a critical role in determining this seasonal phasing through barotropic and first baroclinic mode adjustments and communication to the western boundary via Rossby waves. Our hypothesis is explored using single layer and one‐and‐a‐half layer models. We find that the...
Tipo: Text Palavras-chave: Agulhas Current; Seasonal cycle; Wind stress curl; Rossby waves; Indian Ocean; Reduced gravity model.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00454/56607/58300.pdf
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The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile Gayana
Hormazábal,Samuel; Shaffer,Gary; Silva,Nelson; Navarro,Eduardo.
Ten years of continuous current meter recordings near the core of the Peru-Chile Undercurrent (PCU) over the continental slope at 30°S off Chile, local and equatorial wind stress data, and monthly oceanographic sections off Valparaíso (33°S) are used to study the variability of the PCU and the Oxygen Minimum Zone (OMZ) off Chile. The physics that governs the PCU variability differs for intraseasonal periods and for longer periods: Coastal trapped waves dominate the intraseasonal band whereas Rossby waves dominate for periods greater than about 120 days. Semiannual and annual period fluctuations can largely be explained by Rossby waves forced by equatorial Kelvin waves and local winds. Seasonal variations in the PCU are strongly modulated over El Niño/La...
Tipo: Journal article Palavras-chave: Rossby waves; Oxygen minimum zone; El Niño/La Niña cycles; Peru-Chile Undercurrent.
Ano: 2006 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382006000300009
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The Vertical Structure of Large-Scale Unsteady Currents ArchiMer
Hochet, Antoine; Colin De Verdiere, Alain; Scott, Robert.
A linear model based on the quasigeostrophic equations is constructed in order to predict the vertical structure of Rossby waves and, more broadly, of anomalies resolved by altimeter data, roughly with periods longer than 20 days and with wavelengths larger than 100 km. The subsurface field is reconstructed from sea surface height and climatological stratification. The solution is calculated in periodic rectangular regions with a 3D discrete Fourier transform. The effect of the mean flow on Rossby waves is neglected, which the authors believe is a reasonable approximation for low latitudes. The method used has been tested with an idealized double- gyre simulation [performed with the Miami Isopycnal Coordinate Ocean Model (MICOM)]. The linear model is able...
Tipo: Text Palavras-chave: Circulation/ Dynamics; Ocean dynamics; Rossby waves; Waves; Oceanic; Mathematical and statistical techniques; Fourier analysis; Models and modeling; Quasigeostrophic models.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00260/37081/35586.pdf
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Western boundary upwelling dynamics off Oman ArchiMer
Vic, Clement; Capet, Xavier; Roullet, Guillaume; Carton, Xavier; ,.
Despite its climatic and ecosystemic significance, the coastal upwelling that takes place off Oman is not well understood. A primitive-equation, regional model forced by climatological wind stress is used to investigate its dynamics and to compare it with the better-known Eastern Boundary Upwellings (EBUs). The solution compares favorably with existing observations, simulating well the seasonal cycles of thermal structure, surface circulation (mean and turbulent), and sea-surface temperature (SST). There is a 1.5-month lag between the maximum of the upwelling-favorable wind-stress-curl forcing and the oceanic response (minima in sea-surface height and SST), which we attribute to onshore-propagating Rossby waves. A southwestward-flowing undercurrent...
Tipo: Text Palavras-chave: Oman; Upwelling; Arabian sea; ROMS; Rossby waves; Eddy kinetic energy.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00382/49350/49752.pdf
Registros recuperados: 12
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