Consulta: creatorFacets:"Bourles, Bernard"
Registros recuperados: 17
Data/hora: 05/06/2024 16:07:27

Respective Roles of the Guinea Current and Local Winds on the Coastal Upwelling in the Northern Gulf of Guinea
Provedor de dados: 5
Autores: Djakoure, S.; Penven, Pierrick; Bourles, Bernard; Kone, V.; Veitch, J.
The northern Gulf of Guinea is a part of the eastern tropical Atlantic where oceanic conditions due to the presence of coastal upwelling may influence the regional climate and fisheries. The dynamics of this coastal upwelling is still poorly understood. A sensitivity experiment based on the Regional Oceanic Modeling System (ROMS) is carried out to assess the role of the detachment of the Guinea Current as a potential mechanism for coastal upwelling. This idealized experiment is performed by canceling the inertia terms responsible for the advection of momentum in the equations and comparing with a realistic experiment. The results exhibit two major differences. First, the Guinea Current is found to be highly sensitive to inertia, as it is no longer detached...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00391/50248/69638.pdf

The AMMA field campaigns: accomplishments and lessons learned
Provedor de dados: 5
Autores: Lebel, Thierry; Parker, Douglas J.; Flamant, Cyrille; Hoeller, Hartmut; Polcher, Jan; Redelsperger, Jean-luc; Thorncroft, Chris; Bock, Olivier; Bourles, Bernard; Galle, Sylvie; Marticorena, Beatrice; Mougin, Eric; Peugeot, Christophe; Cappelaere, Bernard; Descroix, Luc; Diedhiou, Arona; Gaye, Amadou; Lafore, Jean-philippe.
The AMMA (African Monsoon Multidiscplinary Analysis) field programme aimed at documenting the West African Monsoon (WAM) climate system, in all its geophysical components. It also includes an important socio-economic component. Encompassing a wide range of spatial and time scales, AMMA is one of the most ambitious such programmes ever set up. While the key accomplishments of AMMA are summarised in this paper, a few lessons of broad interest are also drawn both as a tribute to the extraordinary efforts made by a community of several hundreds of people and as possible guidelines for ensuring a long lasting future to integrated climate and environmental studies in West Africa.
Tipo: Text
Palavras-chave: Field campaigns; Instrument deployment; Long-term monitoring; Capacity building; West Africa.
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00214/32510/30990.pdf

CORIOLIS. Rapport d’activités 2016
Provedor de dados: 5
Autores: Pouliquen, Sylvie; Maze, Guillaume; Lebreton, Nathanaele; D'Ortenzio, Fabrizio; Alory, Gaël; Delcroix, Thierry; Bourles, Bernard; Blouch, Pierre; Guinet, Christophe; Gouriou, Yves; Gaillard, Fabienne; Heyndrickx, Céline; Le Menn, Marc; Testor, Pierre; Donato, Vincent; Charria, Guillaume; Carval, Thierry; Reverdin, Gilles; Emzivat, Gilbert.
Rapport d'activité Coriolis pour l'année 2016 dans le cadre de la convention cadre Coriolis 2014-2020
Tipo: Text
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00388/49970/50562.pdf

A biophysical model of S. aurita early life history in the northern Gulf of Guinea
Provedor de dados: 5
Autores: Kone, Vamara; Lett, Christophe; Penven, Pierrick; Bourles, Bernard; Djakoure, Sandrine.
S. aurita is the most abundant small pelagic fish in the northern Gulf of Guinea. Its reproduction and recruitment depend crucially on environmental conditions. We developed a biophysical model of S. aurita early life history by coupling offline an individual-based model with the regional oceanic modeling system (ROMS). We used this model to investigate the main factors driving variability in eggs and larval dispersal and survival in the northern Gulf of Guinea. Precisely, individuals were released from different spawning areas along the coast and tracked for a period of 28 days corresponding to their planktonic phase. Individuals that remained in the coastal recruitment areas at an age more than 7 days, at which they can supposedly actively retain...
Tipo: Text
Palavras-chave: Hydrodynamic model; Individual-based model; S. aurita early life stage; Recruitment; Upwelling; Northern Gulf of Guinea.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00357/46790/46656.pdf

On the Nutrient distribution and phytoplankton biomass in the Gulf of Guinea equatorial band as inferred from In-situ measurements
Provedor de dados: 5
Autores: Nubi, O A; Bourles, Bernard; Edokpayi, C A; Hounkonnou, M N.
Oceanographic in situ data collected in the Gulf of Guinea during six cruises carried out between 2005 and 2007 were analysed to study the influence of equatorial upwelling on the productivity of the region. At 10°W, observations during boreal summer and autumn cruises captured seasonal upwelling influences. In response to the shoaling pycnocline in June 2005, higher concentrations of nitrate and chlorophyll fluorescence were recorded at the ocean surface in June than in September. Our findings challenge the paradigm that westward advection from the nutrient-rich African coast is responsible for equatorial enrichment in the Gulf of Guinea. Vertical sections of the parameters under study in the summer of 2005 showed no westward advection from 3°E to 10°W...
Tipo: Text
Palavras-chave: Advection; Equatorial undercurrent; Equatorial upwelling; Gulf of Guinea; Nutrients; Phytoplankton biomass.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00621/73324/72489.pdf

Evolving and Sustaining Ocean Best Practices and Standards for the Next Decade
Provedor de dados: 5
Autores: Pearlman, Jay; Bushnell, Mark; Coppola, Laurent; Karstensen, Johannes; Buttigieg, Pier Luigi; Pearlman, Francoise; Simpsons, Pauline; Barbier, Michele; Muller-karger, Frank E.; Munoz-mas, Cristian; Pissierssens, Peter; Chandler, Cyndy; Hermes, Juliet; Heslop, Emma; Jenkyns, Reyna; Achterberg, Eric P.; Bensi, Manuel; Bittig, Henry C.; Blandin, Jerome; Bosch, Julie; Bourles, Bernard; Bozzano, Roberto; Buck, Justin J. H.; Burger, Eugene F.; Cano, Daniel; Cardin, Vanessa; Llorens, Miguel Charcos; Cianca, Andres; Chen, Hua; Cusack, Caroline; Delory, Eric; Garello, Rene; Giovanetti, Gabriele; Harscoat, Valerie; Hartman, Susan; Heitsenrether, Robert; Jirka, Simon; Lara-lopez, Ana; Lanteri, Nadine; Leadbetter, Adam; Manzella, Giuseppe; Maso, Joan; Mccurdy, Andrea; Moussat, Eric; Ntoumas, Manolis; Pensieri, Sara; Petihakis, George; Pinardi, Nadia; Pouliquen, Sylvie; Przeslawski, Rachel; Roden, Nicholas P.; Silke, Joe; Tamburri, Mario N.; Tang, Hairong; Tanhua, Toste; Telszewski, Maciej; Testor, Pierre; Thomas, Julie; Waldmann, Christoph; Whoriskey, Fred.
The oceans play a key role in global issues such as climate change, food security, and human health. Given their vast dimensions and internal complexity, efficient monitoring and predicting of the planet's ocean must be a collaborative effort of both regional and global scale. A first and foremost requirement for such collaborative ocean observing is the need to follow well-defined and reproducible methods across activities: from strategies for structuring observing systems, sensor deployment and usage, and the generation of data and information products, to ethical and governance aspects when executing ocean observing. To meet the urgent, planet-wide challenges we face, methods across all aspects of ocean observing should be broadly adopted by the ocean...
Tipo: Text
Palavras-chave: Best practices; Sustainability; Interoperability; Digital repository; Peer review; Ocean observing; Ontologies; Methodologies.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00503/61423/65111.pdf

Tropical Atlantic Contributions to Strong Rainfall Variability Along the Northeast Brazilian Coast
Provedor de dados: 5
Autores: Hounsou-gbo, G. A.; Araujo, M.; Bourles, Bernard; Veleda, D.; Servain, J.
Tropical Atlantic (TA) Ocean-atmosphere interactions and their contributions to strong variability of rainfall along the Northeast Brazilian (NEB) coast were investigated for the years 1974-2008. The core rainy seasons of March-April and June-July were identified for Fortaleza (northern NEB; NNEB) and Recife (eastern NEB; ENEB), respectively. Lagged linear regressions between sea surface temperature (SST) and pseudo wind stress (PWS) anomalies over the entire TA and strong rainfall anomalies at Fortaleza and Recife show that the rainfall variability of these regions is differentially influenced by the dynamics of the TA. When the Intertropical Convergence Zone is abnormally displaced southward a few months prior to the NNEB rainy season, the associated...
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00624/73567/73008.pdf

SST Indexes in the Tropical South Atlantic for Forecasting Rainy Seasons in Northeast Brazil
Provedor de dados: 5
Autores: Hounsou-gbo, Gbekpo Aubains; Servain, Jacques; Araujo, Moacyr; Caniaux, Guy; Bourles, Bernard; Fontenele, Diogenes; Martins, Eduardo Savio P. R.
May-to-July and February-to-April represent peak rainy seasons in two sub-regions of Northeast Brazil (NEB): Eastern NEB and Northern NEB respectively. In this paper, we identify key oceanic indexes in the tropical South Atlantic for driving these two rainy seasons. In Eastern NEB, the May-to-July rainfall anomalies present a positive relationship with the previous boreal winter sea surface temperature anomalies (SSTA) in the southeast tropical Atlantic (20 degrees-10 degrees S; 10 degrees W-5 degrees E). This positive relationship, which spread westward along the southern branch of the South Equatorial Current, is associated with northwesterly surface wind anomalies. A warmer sea surface temperature in the southwestern Atlantic warm pool increases the...
Tipo: Text
Palavras-chave: Brazilian Northeast; Rainfall; Predictability; Tropical Atlantic.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00623/73547/73807.pdf

French PIRATA cruises S-ADCP data processing
Provedor de dados: 5
Autores: Herbert, Gaelle; Kermabon, Catherine; Grelet, Jacques; Bourles, Bernard.
In the framework of the PIRATA program, several types of observations are carried out in the Tropical Atlantic during yearly cruises, including Shipboard Acoustic Doppler Current Profilers (SADCP) data. The present note is a brief review of the SADCP data processing methodology applied for 8 PIRATA cruises by using CASCADE software. To illustrate the processing steps and demonstrate the CASCADE software capabilities, an example of SADCP data processing obtained from PIRATA-FR24 cruise has been shown. This data set is made available on the PIRATA website and will also be used in the framework of the EU PREFACE program (see http://preface.b.uib.no/).
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00272/38320/36561.pdf

XBT Temperature Errors during French Research Cruises (1999-2007)
Provedor de dados: 5
Autores: Reverdin, Gilles; Marin, Frederic; Bourles, Bernard; Lherminier, Pascale.
Data from French cruises in 1999-2007, a period during which Deep Blue (DB) or T7 expendable bathythermographs (XBTs) were deployed, and for which ancillary temperature data are available in the northeast Atlantic and equatorial Atlantic regions, are examined. There was a total of 16 cruises with XBTs launched between conductivity-temperature-depth (CTD) stations; during most of these, as well as during three additional cruises that were also considered, intake temperature was measured. XBT data from two voluntary observing ships in the North Atlantic subpolar gyre for which intake temperature was measured were also investigated. There is an XBT cold bias due to stirring of a stratified upper layer by the ship, resulting in differences between XBT...
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00133/24380/22391.pdf

Data Descriptor: Stable isotopes in the atmospheric marine boundary layer water vapour over the Atlantic Ocean, 2012-2015
Provedor de dados: 5
Autores: Benetti, Marion; Steen-larsen, Hans Christian; Reverdin, Gilles; Sveinbjornsdottir, Arny Erla; Aloisi, Giovanni; Berkelhammer, Max B.; Bourles, Bernard; Bourras, Denis; De Coetlogon, Gaelle; Cosgrove, Ann; Faber, Anne-katrine; Grelet, Jacques; Hansen, Steffen Bo; Johnson, Rod; Legoff, Herve; Martin, Nicolas; Peters, Andrew J.; Popp, Trevor James; Reynaud, Thierry; Winther, Malte.
The water vapour isotopic composition ( (H2O)-H-1-O-16, (H2O)-O-18 and (HHO)-H-1-H-2-O-16) of the Atlantic marine boundary layer has been measured from 5 research vessels between 2012 and 2015. Using laser spectroscopy analysers, measurements have been carried out continuously on samples collected 10-20 meter above sea level. All the datasets have been carefully calibrated against the international VSMOW-SLAP scale following the same protocol to build a homogeneous dataset covering the Atlantic Ocean between 4 degrees S to 63 degrees N. In addition, standard meteorological variables have been measured continuously, including sea surface temperatures using calibrated Thermo-Salinograph for most cruises. All calibrated observations are provided with...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00371/48195/48312.pdf

Impact of intraseasonal wind bursts on sea surface temperature variability in the far eastern tropical Atlantic Ocean during boreal spring 2005 and 2006: focus on the mid-May 2005 event
Provedor de dados: 5
Autores: Herbert, Gaelle; Bourles, Bernard.
The impact of boreal spring intraseasonal wind bursts on sea surface temperature variability in the eastern tropical Atlantic Ocean in 2005 and 2006 is investigated using numerical simulation and observations. We especially focus on the coastal region east of 5 degrees E and between the Equator and 7 degrees S that has not been studied in detail so far. For both years, the southerly wind anomalies induced cooling episodes through (i) upwelling processes, (ii) vertical mixing due to the vertical shear of the current, and for some particular events (iii) a decrease in incoming surface shortwave radiation. The strength of the cooling episodes was modulated by subsurface conditions affected by the arrival of Kelvin waves from the west influencing the depth of...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00623/73550/73801.pdf

Western boundary currents and transports off french-guiana as inferred from pegasus observations
Provedor de dados: 5
Autores: Colin, C; Bourles, Bernard.
Pegasus current measurements carried out along a section located off French Guiana are presented; the section was repeated five times from September 1989 to June 1991 during the NOE (region Nord-Ouest equatoriale)/STACS (Sub Tropical Atlantic Climate Studies) cruises on board the NOAA (National Oceanographic and Atmospheric Administration) research vessels. The data (vertical and horizontal distributions) show, as suggested by earliest observations, the presence of different currents. At the surface, and in winter, the North Brazil Current (NBC) flows northwestward (positive), is strong (120 cm/s), confined in the first 250 m, coastally trapped (within 250 km) and fed by offshore waters; in summer the NBC strengthens (the velocity increases to 150 cm/s),...
Tipo: Text
Palavras-chave: CURRENTS; TEMPERATURE; SALINITY; WESTERN BOUNDARY; EQUATORIAL ATLANTIC.
Ano: 1994
URL: http://archimer.ifremer.fr/doc/00098/20881/18495.pdf

Downwelling surface solar irradiance in the tropical Atlantic Ocean: a comparison of re-analyses and satellite-derived data sets to PIRATA measurements
Provedor de dados: 5
Autores: Trolliet, Melodie; Walawender, Jakub P.; Bourles, Bernard; Boilley, Alexandre; Trentmann, Joerg; Blanc, Philippe; Lefevre, Mireille; Wald, Lucien.
This paper assesses the merits and drawbacks of several data sets of solar downwelling radiation received at the horizontal surface of the tropical Atlantic Ocean where the magnitude of this radiation and its spatial and temporal variability are not well known. The data sets are compared to quality-controlled measurements of hourly means of irradiance made at five buoys of the PIRATA network for the period 2012-2013. The data sets comprise the re-analyses MERRA-2 and ERAS, and three satellite-derived data sets: HelioClim-3v5, SARAH-2 and CAMS Radiation Service v2. It was found that the re-analyses MERRA-2 and ERAS often report cloud-free conditions while the actual conditions are cloudy, yielding an overestimation of the irradiance in such cases; and...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00623/73549/73802.pdf

Seasonal cycle of the salinity barrier layer revealed in the northeastern Gulf of Guinea
Provedor de dados: 5
Autores: Dossa, A. N.; Da-allada, C. Y.; Herbert, G; Bourles, Bernard.
The region located in the far northeast of the Gulf of Guinea (NEGG), eastern tropical Atlantic, remains poorly documented due to a lack of available in situ ocean data. Heavy rainfall and intense river discharges observed in this region induce a strong salinity stratification that may have a significant impact on the mixed layer depth and on sea surface temperatures, through the so-called barrier-layer effect. By using recent in situ data and climatological outputs from a numerical simulation, we reveal the existence of a barrier layer in the NEGG and describe its seasonal occurrence. In the NEGG, the barrier layer limits the mixed layer depth. From January to March, significant values for the barrier-layer thickness are observed mostly due to the...
Tipo: Text
Palavras-chave: Mixed layer depth; Niger River discharge; Numerical model; Oceanography; Sea surface salinity; Tropical Atlantic; Vertical stratification.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00509/62103/66273.pdf

Sensitivity of near-surface Tropical Instability Waves to submonthly wind forcing in the tropical Atlantic
Provedor de dados: 5
Autores: Athie, Gabriela; Marin, Frederic; Treguier, Anne-marie; Bourles, Bernard; Guiavarc'H, Catherine.
This study demonstrates the sensitivity of the near-surface properties in the tropical Atlantic Ocean to the high-frequency of the winds in numerical simulations. At intra-seasonal timescales (2-50 days), two distinct period ranges dominate the variability in the upper ocean: periods between 2 and 20 days, which are essentially wind-forced and periods between 20 and 50 days, due mostly to Tropical Instability Waves (TIWs). Using a numerical model forced by different wind fields, it is shown that the characteristics of the intra-seasonal variability in the ocean surface mixed-layer are strongly dependent on the wind forcing. Submonthly winds are shown to force large variability in the upper ocean that can strikingly decrease the amplitude of the TIWs in the...
Tipo: Text
Palavras-chave: Equatorial Atlantic; Intra seasonal variability; Tropical instabilities; Ocean mixed layer; Sensitivity numerical experiments.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00000/11117/7967.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