Consulta: subjectFacets:"Subpolar gyre"
Registros recuperados: 8
Data/hora: 13/06/2024 00:20:48

Sea surface temperature variability in the Norwegian Sea during the late Pliocene linked to subpolar gyre strength and radiative forcing
Provedor de dados: 5
Autores: Bachem, Paul E.; Risebrobakken, Bjorg; Mcclymont, Erin L.
The mid-Piacenzian warm period (3.264-3.025 Ma) of the Pliocene epoch has been proposed as a possible reference for future warm climate states. However, there is significant disagreement over the magnitude of high latitude warming between data and models for this period of time, raising questions about the driving mechanisms and responsible feedbacks. We have developed a new set of orbital-resolution alkenone-based sea surface temperature (SST) and ice rafted debris (IRD) records from the Norwegian Sea spanning 3.264-3.14 Ma. The SSTs in the Norwegian Sea were 2-3 degrees C warmer than the Holocene average, likely caused by the radiative effect of higher atmospheric CO2 concentrations. There is notable obliquity-driven SST variability with a range of 4...
Tipo: Text
Palavras-chave: Pliocene; Norwegian Sea; ODP Site 642; Alkenones; SST; Subpolar gyre.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00421/53230/83372.pdf

Improvements of simulated Western North Atlantic current system and impacts on the AMOC
Provedor de dados: 5
Autores: Talandier, Claude; Deshayes, Julie; Treguier, Anne-marie; Capet, Xavier; Benshila, Rachid; Debreu, Laurent; Dussin, Raphael; Molines, J. -m.; Madec, Gerard.
Previous studies have shown that low horizontal resolution (of the order of 1°) ocean models, hence climate models, are not able to adequately represent boundary currents nor mesoscale processes which affect the dynamics and thermohaline circulation of the ocean. While the effect of mesoscale eddies can be parameterized in low resolution models, boundary currents require relatively high horizontal resolution. We clarify the impact of increasing the resolution on the North Atlantic circulation, with emphasis on the Atlantic Meridional Overturning Circulation (AMOC), by embedding a 1/8° nest covering the North Atlantic into a global 1/2° model.  Increasing the resolution in the nest leads to regional improvements of the circulation and thermohaline...
Tipo: Text
Palavras-chave: Deep Western Boundary Current; Atlantic Meridional Overturning Circulation; North Atlantic Current; Gulf Stream; Subpolar gyre.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00173/28472/26812.pdf

Caractérisation de la circulation autour, au-dessus et à travers (via des zones de fracture) la dorsale de Reykjanes
Provedor de dados: 5
Autores: Petit, Tillys.
The Reykjanes Ridge is a major topographic feature of the North-Atlantic Ocean that extends from Iceland to the Charlie Gibbs Fracture Zone. Located between the Iceland Basin and the Irminger Sea, the Reykjanes Ridge strongly influences the subpolar gyre circulation and is a gate toward the deep convection areas. However, the circulation and distribution across the Reykjanes Ridge has never been directly quantified such that the characterization of the connection between the Iceland Basin and the Irminger Sea is still incomplete. As part of the Reykjanes Ridge Experiment project, we were able to analyze the circulation around, above and across the Reykjanes Ridge. Mainly based on hydrographic sections along and perpendicular to the ridge axis, the aim of...
Tipo: Text
Palavras-chave: Gyre subpolaire Nord-Atlantique; Bathymétrie; Masses d’eau; North-Atlantic; Subpolar gyre; Bathymetry; Water masses; Circulation; Observations.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00498/60969/64377.pdf

Les Eaux Modales du gyre subpolaire de l'Atlantique Nord : origine, formation, variabilité
Provedor de dados: 5
Autores: De Boisseson, Eric.
The subpolar Mode Waters of the North Atlantic ocean play a key role in the general oceanic surface circulation. Their life cycle has only been described from an average of observations over several decades. This description avoids the real time scale of this life cycle and smooths its variaribility. It also does not adress the setting the Mode Water properties. This thesis work deals with these aspects by analysing both the ORCA025-G70 model fields and the observations.The lagrangian analysis of the ORCA025-G70 fields highlights the key role of the North Atlantic current in the life cycle of the Mode Waters. The Mode Waters are fed and carried by this current. They form during the winter mixed layer deepening due to the surface atmospheric fluxes. The...
Tipo: Text
Palavras-chave: ORCA025 G70; Lagrangian analysis; Argo; Advection; Atmospheric fluxes; North Atlantic current; Subpolar gyre; North Atlantic; Mode water; ORCA025 G70; Analyse lagrangienne; Argo; Advection; Flux atmosphériques; Courant Nord Atlantique; Gyre subpolaire; Atlantique Nord; Eau modale.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/2010/these-7469.pdf

The Atlantic Meridional Overturning Circulation and the subpolar gyre observed at the A25-OVIDE section in June 2002 and 2004
Provedor de dados: 5
Autores: Lherminier, Pascale; Mercier, Herle; Huck, Thierry; Gourcuff, Claire; Perez, Fiz F.; Morin, Pascal; Sarafanov, Artem; Falina, Anastasia.
The horizontal circulation of the subpolar gyre and the Meridional Overturning Circulation (MOC) are investigated here by comparing two snapshots of the North Atlantic as delivered by two hydrographic sections between Greenland and Portugal. The corresponding cruises were carried out in June–July 2002 and June–July 2004 on R/V Thalassa within the framework of the Ovide project. The absolute transports in June 2004 are described in detail, and then compared with transports in June 2002. The MOC (in density coordinates), driven by the volume balance between the northward North Atlantic Current (NAC) and the net southward export of dense water from the subpolar gyre, did not change: View the MathML source (1 Sv=106 m3 s−1). Its upper limb, above σ1=32.1, is...
Tipo: Text
Palavras-chave: North Atlantic; Subpolar gyre; Meridional Overturning Circulation; OVIDE; Hydrology; ADCP.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00011/12272/9057.pdf

Evolution of the northeast Labrador Sea during the last interglaciation
Provedor de dados: 5
Autores: Winsor, Kelsey; Carlson, Anders E.; Klinkhammer, Gary P.; Stoner, Joseph S.; Hatfield, Robert G.
Boreal summer insolation during the last interglaciation (LIG) generally warmed the subpolar to polar Northern Hemisphere more than during the early Holocene, yet regional climate variations between the two periods remain. We investigate northeast Labrador Sea subsurface temperature and hydrography across terminations (T) I and II and during the LIG to assess the impact of two different magnitudes of boreal summer insolation increase on the northeast Labrador Sea. We use Mg/Ca ratios in Neogloboquadrina pachyderma (sinistral) as a proxy of calcification temperature to document changes in subsurface temperatures over Eirik Drift. Our corresponding record of delta O-18 of seawater documents changes in water mass salinity. Mg/Ca calcification temperatures...
Tipo: Text
Palavras-chave: Neogloboquadrina pachyderma (sinistral); Labrador Sea; Mg/Ca; Deglaciations; Interglaciations; Subpolar gyre.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00265/37604/36840.pdf

Mid to late Holocene strengthening of the East Greenland Current linked to warm subsurface Atlantic water
Provedor de dados: 5
Autores: Perner, Kerstin; Moros, Matthias; Lloyd, Jeremy M.; Jansen, Eystein; Stein, Ruediger.
The relatively fresh and cold East Greenland Current (EGC) connects the Arctic with the subpolar North Atlantic Ocean. Its strength and influence on the freshwater balance in the North Atlantic affects both the Subpolar Gyre dynamics and deep convection in the Labrador Sea. Enhanced freshwater and sea-ice expansion in the subpolar North Atlantic is suggested to modify the northward heat transport within the North Atlantic Current. High-resolution palaeoceanographic reconstructions, based on planktic and benthic foraminifera assemblage data, from the central East Greenland shelf (Foster Bugt) reveal distinct centennial to millennial-scale oceanographic variability that relates to climatic changes during the mid to late Holocene (the last c. 6.3 ka BP). Our...
Tipo: Text
Palavras-chave: Foraminifera; East Greenland Current; Return Atlantic Current; Subpolar gyre; Polar front; Subpolar north Atlantic; Mid to late Holocene.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00496/60725/83614.pdf

Etude de la variabilité de la circulation du gyre subpolaire de l'Atlantique Nord à partir des données Ovide et de mesures satellitaires
Provedor de dados: 5
Autores: Gourcuff, Claire.
The cyclonic circulation of the North Atlantic subpolar gyre, between 50°N and 63°N, plays a key role in the climate variability. The Ovide program contributes to the observation of the circulation in this region. A section is repeated every two years in summer since 2002 between Greenland and Portugal following a path close the Fourex 1997 section. To get transport estimates across the sections, a geostrophic box inverse model is used, constrained with direct current measurements.  Our new estimates of Fourex transports show the need to use constraints temporally associated with the section to get transports estimates representative of the circulation at the section realisation dates. It is also shown that altimetry velocities can be used instead of ADCP...
Tipo: Text
Palavras-chave: Inverse Model; Courantology; Geostrophy; Altimetry; East Greenland Coastal Current; Freshwater fluxes; Heat transport; Meridionnal Overturning Circulation (MOC); Variability; North Atlantic; Subpolar gyre; Ovide; Modèle inverse; Géostrophie; Courantométrie; Altimétrie; Courant Côtier Est Groenlandais; Flux d'eau douce; Transport de chaleur; Circulation Méridienne de Retournement (MOC); Variabilité; Atlantique Nord; Gyre subpolaire; Ovide.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/these-6226.pdf