Consulta: creatorFacets:"Jouanno, Julien"
Registros recuperados: 9
Data/hora: 06/06/2024 11:37:45

Benguela Niños and Benguela Niñas in forced ocean simulation from 1958 to 2015
Provedor de dados: 5
Autores: Imbol Koungue, Rodrigue Anicet; Rouault, Mathieu; Illig, Serena; Brandt, Peter; Jouanno, Julien.
A systematic study of Benguela Niño and Benguela Niña events during 1958 to 2015 including those that developed before the satellite era (1982) is carried out using an ocean general circulation model in combination with a linear equatorial model. Altogether, 21 strong warm and cold anomalous coastal events are identified among which 6 undocumented extreme coastal events are reported. Results suggest that most of these extreme coastal events including the newly identified ones are linked to remote equatorial forcing via mode 2 equatorial Kelvin waves. The latter propagates after approaching the African coast poleward as coastally trapped waves leading surface temperature anomalies along the Angola‐Benguela current system by 1 month. 1‐2 months before the...
Tipo: Text
Palavras-chave: Benguela Ninos; Benguela Ninas; Equatorial Kelvin waves; Upwelling; South Atlantic anticyclone.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00509/62110/66302.pdf

Modeled mixed-layer salinity balance in the Gulf of Guinea: seasonal and interannual variability
Provedor de dados: 5
Autores: Da-allada, Casimir Yelognisse; Du Penhoat, Yves; Jouanno, Julien; Alory, Gael; Hounkonnou, Norbert Mahouton.
A regional numerical simulation and observations were used to investigate the various processes controlling mixed-layer salinity balance on seasonal and interannual time scales in the Gulf of Guinea. Processes were quantified using a mixed-layer salt budget. Model results correctly reproduced the mean, phase, and amplitude of observed seasonal near-surface salinity. The results indicated that on seasonal time scales, the mixed-layer salinity balance differed from one region to another. The surface salinity seasonal cycle was characterized by strong salinization during May for coastal areas north and south of the equator. Model results suggested that vertical mixing controls the mixed-layer salinity increase at the equator during May, while both vertical...
Tipo: Text
Palavras-chave: Sea surface salinity; Gulf of guinea; Model; Mixed-layer budget; Seasonal variability; Interannual variability.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00242/35333/36310.pdf

Dissipation of the energy imparted by mid-latitude storms in the Southern Ocean
Provedor de dados: 5
Autores: Jouanno, Julien; Capet, Xavier; Madec, Gurvan; Roullet, Guillaume; Klein, Patrice.
The aim of this study is to clarify the role of the Southern Ocean storms on interior mixing and meridional overturning circulation. A periodic and idealized numerical model has been designed to represent the key physical processes of a zonal portion of the Southern Ocean located between 70 and 40° S. It incorporates physical ingredients deemed essential for Southern Ocean functioning: rough topography, seasonally varying air–sea fluxes, and high-latitude storms with analytical form. The forcing strategy ensures that the time mean wind stress is the same between the different simulations, so the effect of the storms on the mean wind stress and resulting impacts on the Southern Ocean dynamics are not considered in this study. Level and distribution of...
Tipo: Text
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00343/45404/44919.pdf

Contribution of the Amazon River Discharge to Regional Sea Level in the Tropical Atlantic Ocean
Provedor de dados: 5
Autores: Giffard, Pierrick; Llovel, William; Jouanno, Julien; Morvan, Guillaume; Decharme, Bertrand.
Tipo: Text
Palavras-chave: Sea level; Amazon River; River plume; Salinity; Model; NEMO; Tropical Atlantic.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00591/70268/68327.pdf

A model perspective on the dynamics of the shadow zone of the eastern tropical North Atlantic - Part 1: the poleward slope currents along West Africa
Provedor de dados: 5
Autores: Kounta, Lala; Capet, Xavier; Jouanno, Julien; Kolodziejczyk, Nicolas; Sow, Bamol; Gaye, Amadou Thierno.
The West African seaboard is one of the upwelling sectors that has received the least attention, and in situ observations relevant to its dynamics are particularly scarce. The current system in this sector is not well known and understood, e.g., in terms of seasonal variability, across-shore structure, and forcing processes. This knowledge gap is addressed in two studies that analyze the mean seasonal cycle of an eddy-permitting numerical simulation of the tropical Atlantic. Part 1 is concerned with the circulation over the West African continental slope at the southernmost reach of the Canary Current system, between similar to 8 and 20 degrees N. The focus is on the depth range most directly implicated in the wind-driven circulation (offshore and coastal...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00458/56969/58862.pdf

From Mixing to the Large Scale Circulation: How the Inverse Cascade Is Involved in the Formation of the Subsurface Currents in the Gulf of Guinea
Provedor de dados: 5
Autores: Assene, Fernand; Morel, Yves; Delpech, Audrey; Aguedjou, Micael; Jouanno, Julien; Cravatte, Sophie; Marin, Frederic; Ménesguen, Claire; Chaigneau, Alexis; Dadou, Isabelle; Alory, Gael; Holmes, Ryan; Bourlès, Bernard; Koch-larrouy, Ariane.
In this paper, we analyse the results from a numerical model at high resolution. We focus on the formation and maintenance of subsurface equatorial currents in the Gulf of Guinea and we base our analysis on the evolution of potential vorticity (PV). We highlight the link between submesoscale processes (involving mixing, friction and filamentation), mesoscale vortices and the mean currents in the area. In the simulation, eastward currents, the South and North Equatorial Undercurrents (SEUC and NEUC respectively) and the Guinea Undercurrent (GUC), are shown to be linked to the westward currents located equatorward. We show that east of 20∘ W, both westward and eastward currents are associated with the spreading of PV tongues by mesoscale vortices. The...
Tipo: Text
Palavras-chave: Equatorial atlantic; NEUC (North Equatorial Undercurrents); SEUC (South Equatorial Undercurrents); Vortices; Mixing; Friction.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00645/75697/76601.pdf

Equatorial Atlantic interannual variability and its relation to dynamic and thermodynamic processes
Provedor de dados: 5
Autores: Jouanno, Julien; Hernandez, Olga; Sanchez-gomez, Emilia.
The contributions of the dynamic and thermodynamic forcing to the interannual variability of the equatorial Atlantic sea surface temperature (SST) are investigated using a set of interannual regional simulations of the tropical Atlantic Ocean. The ocean model is forced with an interactive atmospheric boundary layer, avoiding damping toward prescribed air temperature as is usually the case in forced ocean models. The model successfully reproduces a large fraction (R-2 = 0.55) of the observed interannual variability in the equatorial Atlantic. In agreement with leading theories, our results confirm that the interannual variations of the dynamical forcing largely contributes to this variability. We show that mean and seasonal upper ocean temperature biases,...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00623/73554/73795.pdf

The Amazon River: A Major Source of Organic Plastic Additives to the Tropical North Atlantic?
Provedor de dados: 5
Autores: Schmidt, Natascha; Fauvelle, Vincent; Ody, Anouck; Castro Jimenez, Javier; Jouanno, Julien; Changeux, Thomas; Thibaut, Thierry; Sempéré, Richard.
The release of emerging organic contaminants is identified among the most critical hazards to the marine environment, and plastic additives have received growing attention due to their worldwide distribution and potential deleterious effects. Here, we report dissolved surface water concentrations of two important families of plastic additives (organophosphate esters (OPEs) and bisphenols) and other related organic compounds (perfluorinated chemicals) measured in the North Atlantic from Cape Verde to the West Indies. We found that OPEs were the most abundant contaminants, reaching remarkably high concentrations in open ocean waters (1200 km offshore of the American Coast, at the location of the Amazon river plume during the sampling period), with up to 1.3...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00514/62607/66967.pdf

Physical drivers of the nitrate seasonal variability in the Atlantic cold tongue
Provedor de dados: 5
Autores: Radenac, Marie-helene; Jouanno, Julien; Tchamabi, Christine Carine; Awo, Mesmin; Bourles, Bernard; Arnault, Sabine; Aumont, Olivier.
Ocean color observations show semiannual variations in chlorophyll in the Atlantic cold tongue with a main bloom in boreal summer and a secondary bloom in December. In this study, ocean color and in situ measurements and a coupled physical-biogeochemical model are used to investigate the processes that drive this variability. Results show that the main phytoplankton bloom in July-August is driven by a strong vertical supply of nitrate in May-July, and the secondary bloom in December is driven by a shorter and moderate supply in November. The upper ocean nitrate balance is analyzed and shows that vertical advection controls the nitrate input in the equatorial euphotic layer and that vertical diffusion and meridional advection are key in extending and...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00623/73546/73808.pdf