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| Registros recuperados: 151 | |
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| Monaco, André; Peruzzi, Stefano. |
| The papers presented in this volume represent only a small part of the results obtained within the scope of the first integrated programme concerning the Mediterranean Sea. The latter is considered as a downscaled model of the ocean system, and a regional sea for the targeted projects supported by the European Commission. Whatever the domain is, the variability of the system appeared as a major feature. Consequently, this theme has been selected, among the main initial objectives, as the central subject of this volume. Spatial and temporal variabilities are considered, at different scales and at different (water, particles, sediment, trophic) levels of the marine ecosystem. In the hereafter contributions, one will find the long-term (millenar, secular and... |
| Tipo: Text |
Palavras-chave: Climate; Pluridisciplinary; Variability; Mediterranean; Marine system. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-783.pdf |
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| Gerin, R.; Poulain, P. -m.; Taupier-letage, Isabelle; Millot, C.; Ben Ismail, S.; Sammari, Cherif. |
| Within the framework of the EGITTO/EGYPT programs, the spatial structure and the temporal variability of the surface circulation in the eastern basin of the Mediterranean Sea was studied with satellite-tracked drifters. A total of 97 drifters drogued to 15-m nominal depth were released between September 2005 and March 2007, regularly along ship-of-opportunity routes in the Sicily Channel and within specific structures during dedicated campaigns in the Levantine sub-basin. This study complements previous ones in the former and in the Ionian, but it is the first one in the latter. After editing and low-pass filtering, the drifter trajectories were used to estimate pseudo-Eulerian statistics: mean current, variance ellipses, mean and eddy kinetic energies. A... |
| Tipo: Text |
Palavras-chave: Lagrangian drifters; General circulation; Undrogued drifters; Sea; Variability; Features; Basin; Model; Dynamics. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00204/31480/29891.pdf |
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| Hufnagl, Marc; Payne, Mark; Lacroix, Genevieve; Bolle, Loes J.; Daewele, Ute; Dickey-collas, Mark; Gerkema, Theo; Huret, Martin; Janssen, Frank; Kreus, Markus; Paetsch, Johannes; Pohlmann, Thomas; Ruardij, Piet; Schrum, Corinna; Skogen, Morten D.; Tiessen, Meinard C. H.; Petitgas, Pierre; Van Beek, Jan K. L.; Van Der Veer, Henk W.; Callies, Ulrich. |
| Hydrodynamic Ocean Circulation Models and Lagrangian particle tracking models are valuable tools e.g. in coastal ecology to identify the connectivity between offshore spawning and coastal nursery areas of commercially important fish, for risk assessment and more for defining or evaluating marine protected areas. Most studies are based on only one model and do not provide levels of uncertainty. Here this uncertainty was addressed by applying a suite of 11 North Sea models to test what variability can be expected concerning connectivity. Different notional test cases were calculated related to three important and well-studied North Sea fish species: herring (Clupea harengus), and the flatfishes sole (Solea solea) and plaice (Pleuronectes platessa). For sole... |
| Tipo: Text |
Palavras-chave: Ocean circulation; Lagrangian approach; Variability; Marine protected areas; Renewable energy; Wind park; Model intercomparison; Ensemble. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00385/49660/50198.pdf |
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| Halo, Issufo; Penven, Pierrick; Backeberg, Bjoern; Ansorge, Isabelle; Shillington, Frank; Roman, Raymond. |
| In this study, we used more than 17 years of satellite altimetry observations and output from an ocean model to investigate the mesoscale eddy variability and forcing mechanisms to the south of Madagascar. Analysis of energy conversion terms in the model has shown seasonality on eddy formation, both by barotropic and baroclinic instabilities: maximum in winter (JJA) and minimum in summer (DJF). The eddies were mainly formed in the upper ocean (0–300 m) and at intermediate depths (800–2000 m) by barotropic and baroclinic instabilities, respectively. The former dominated in the southeastern margin of Madagascar, and the latter to the southwest, where the South-East Madagascar Current (SEMC) separates from the continental shelf. Seasonality of the eddy... |
| Tipo: Text |
Palavras-chave: Mesoscale eddies; Barotropic; Baroclinic instabilities; Seasonality; Eddy properties; Variability. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00222/33348/31749.pdf |
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| Couldrey, Matthew P.; Oliver, Kevin I. C.; Yool, Andrew; Halloran, Paul R.; Achterberg, Eric P.. |
| The North Atlantic is an important basin for the global ocean's uptake of anthropogenic and natural carbon dioxide (CO2), but the mechanisms controlling this carbon flux are not fully understood. The air-sea flux of CO2, F, is the product of a gas transfer velocity, k, the air-sea CO2 concentration gradient, Delta pCO(2), and the temperature-and salinity-dependent solubility coefficient, alpha, k is difficult to constrain, representing the dominant uncertainty in F on short (instantaneous to interannual) timescales. Previous work shows that in the North Atlantic, Delta pCO(2) and k both contribute significantly to interannual F variability but that k is unimportant for multidecadal variability. On some timescale between interannual and multidecadal, gas... |
| Tipo: Text |
Palavras-chave: Carbon flux; Gas transfer velocity; Carbon cycle; Ocean model; Climate dynamics; Variability. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00383/49418/49868.pdf |
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| Vialard, Jerome; Shenoi, S. S. C.; Mccreary, J. P.; Shankar, D.; Durand, F.; Fernando, V.; Shetye, S. R.. |
| A new observational record of upper-ocean currents at 15 degrees N on the western coast of India is dominated by intraseasonal (55 - 110 day) variations of alongshore currents, whereas sea level at the same location has a clear seasonal signal. These observations can be interpreted within the framework of linear wave theory. At 15 degrees N, the minimum period for planetary waves is similar to 90 day, meaning that intraseasonal energy is largely trapped at the coast in the form of poleward-propagating Kelvin waves, while lower-frequency signals associated with the annual cycle can radiate offshore as planetary waves. This dynamical difference results in a steeper offshore slope of sea level at intraseasonal timescale, and thus stronger geostrophic... |
| Tipo: Text |
Palavras-chave: Variability; Dynamics; Circulation; Currents. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00185/29631/27993.pdf |
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| Landschuetzer, Peter; Ilyina, Tatiana; Lovenduski, Nicole S.. |
| We use a neural network-based estimate of the sea surface partial pressure of CO2 (pCO(2)) derived from measurements assembled within the Surface Ocean CO2 Atlas to investigate the dominant modes of pCO(2) variability from 1982 through 2015. Our analysis shows that detrended and deseasonalized sea surface pCO(2) varies substantially by region and the respective frequencies match those from the major modes of climate variability (Atlantic Multidecadal Oscillation, Pacific Decadal Oscillation, multivariate ENSO index, Southern Annular Mode), suggesting a climate modulated air-sea exchange of CO2. We find that most of the regional pCO(2) variability is driven by changes in the ocean circulation and/or changes in biology, whereas the North Atlantic variability... |
| Tipo: Text |
Palavras-chave: Ocean; CO2; Variability; Carbon; Climate; Observations. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00675/78733/80972.pdf |
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| Marchal, Olivier; Waelbroeck, Claire; Colin De Verdiere, Alain. |
| Three sediment records of sea surface temperature (SST) are analyzed that originate from distant locations in the North Atlantic, have centennial-to-multicentennial resolution, are based on the same reconstruction method and chronological assumptions, and span the past 15 000 yr. Using recursive least squares techniques, an estimate of the time-dependent North Atlantic SST field over the last 15 kyr is sought that is consistent with both the SST records and a surface ocean circulation model, given estimates of their respective error (co)variances. Under the authors' assumptions about data and model errors, it is found that the 10 degrees C mixed layer isotherm, which approximately traces the modern Subpolar Front, would have moved by ~15 degrees of... |
| Tipo: Text |
Palavras-chave: Inverse methods; Kalman filters; Climate variability; Circulation/ Dynamics; Geographic location/entity; Oceanic variability; Variability; Mathematical and statistical techniques; Fronts; North Atlantic Ocean. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00318/42922/42423.pdf |
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| Qiu, Bo; Chen, Shuiming; Klein, Patrice; Sasaki, Hideharu; Sasai, Yoshikazu. |
| Located at the center of the western North Pacific Subtropical Gyre, the Subtropical Countercurrent (STCC) is not only abundant in mesoscale eddies, but also exhibits prominent submesoscale eddy features. Output from a 1/30 degrees high-resolution OGCM simulation and a gridded satellite altimetry product are analyzed to contrast the seasonal STCC variability in the mesoscale versus submesoscale ranges. Resolving the eddy scales of >150 km, the altimetry product reveals that the STCC eddy kinetic energy and rms vorticity have a seasonal maximum in May and April, respectively, a weak positive vorticity skewness without seasonal dependence, and an inverse (forward) kinetic energy cascade for wavelengths larger (shorter) than 250 km. In contrast, the... |
| Tipo: Text |
Palavras-chave: Circulation/ Dynamics; Eddies; Instability; Mesoscale processes; Observational techniques and algorithms; Altimetry; Models and modeling; Ocean models; Variability; Seasonal variability. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00245/35588/34142.pdf |
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| Risebrobakken, B; Jansen, E; Andersson, C; Mjelde, E; Hevroy, K. |
| High-resolution records from IMAGES core MD95-2011 in the eastern Norwegian Sea provide evidence for relatively large- and small-scale high-latitude climate variability throughout the Holocene. During the early and mid-Holocene a situation possibly driven by consistent stronger westerlies increased the eastward influence of Arctic intermediate and near-surface waters. For the late Holocene a relaxation of the atmospheric forcing resulted in increased influence of Atlantic water. The main changes in Holocene climate show no obvious connection to changing solar irradiance, and spectral analysis reveals no consistent signature for any periodic behavior of Holocene climate at millennial or centennial timescales. There are, however, indications of consistent... |
| Tipo: Text |
Palavras-chave: Holocene; Climate; Nordic Seas; NAO; High resolution; Variability. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00224/33500/32119.pdf |
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| Kienast, M.; Lehmann, M. F.; Timmermann, A.; Galbraith, E.; Bolliet, T.; Holboum, A.; Normandeau, C.; Laj, C.. |
| Sedimentary delta(15)N records from the oligotrophic western equatorial Pacific (WEP) off Mindanao show that late Holocene sedimentary delta(15)N is substantially lower than that of the early Holocene, following a gradual >3 parts per thousand decrease that occurred between 7 and 3 kyrs ago. Analyses of modem day nitrate isotope profiles from the same region indicate the sensitivity of the WEP N pools towards (1) the advection of (15)N-enriched nitrate from the Eastern Equatorial Pacific (EEP) by the North Equatorial Current (NEC) and the Mindanao Current in subsurface waters and, (2) at shallow depths, the input of new and (15)N-depleted nitrate through N, fixation. We suggest that the Holocene decrease in sedimentary delta(15)N reflects a diminished... |
| Tipo: Text |
Palavras-chave: Tropical Pacific; El Nino; Surface temperature; Fresh water; Nitrate; Mindanao; Ocean; Variability; Holocene; Seawater. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00207/31843/30257.pdf |
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| Registros recuperados: 151 | |
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