Consulta: creatorFacets:"Loyer, Sophie"
Registros recuperados: 6
Data/hora: 07/06/2024 08:58:33

Dual-frequency ADCPs measuring turbidity
Provedor de dados: 5
Autores: Jourdin, Frederic; Tessier, Caroline; Le Hir, Pierre; Verney, Romaric; Lunven, Michel; Loyer, Sophie; Lusven, Andre; Filipot, Jean-francois; Lepesqueur, Jeremy.
A pair of self-contained acoustic Doppler current profilers (SC-ADCPs) operating with different frequencies were moored on a muddy sea bottom at about 20 m depth in the Bay of Vilaine off the French Atlantic coast. With their acoustic beams oriented upwards, the SC-ADCPs ensonified most of the water column. The results of several months of in situ recorded echo intensity data spanning 2 years (2003 to 2004) from the dual-frequency ADCPs are presented in this paper. The aim was to estimate suspended particle mass concentration and mean size. A concentration index CI is proposed for the estimation of particle concentration. Based on theory the CI-unlike the volume backscatter strength-does not depend on particle size. Compared with in situ optical data, the...
Tipo: Text
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00213/32427/30896.pdf

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas
Provedor de dados: 5
Autores: Roche, Marc; Degrendele, Koen; Vrignaud, Christophe; Loyer, Sophie; Le Bas, Tim; Augustin, Jean-marie; Lurton, Xavier.
The increased use of backscatter measurements in time series for environmental monitoring necessitates the comparability of individual results. With the current lack of pre-calibrated multibeam echosounder systems for absolute backscatter measurement, a pragmatic solution is the use of natural reference areas for ensuring regular assessment of the backscatter measurement repeatability. This method mainly relies on the assumption of a sufficiently stable reference area regarding its backscatter signature. The aptitude of a natural area to provide a stable and uniform backscatter response must be carefully considered and demonstrated by a sufficiently long time-series of measurements. Furthermore, this approach requires a strict control of the acquisition...
Tipo: Text
Palavras-chave: Multibeam echosounder; Seafloor backscatter; Repeatability; Calibration; Reference area; Monitoring.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00422/53384/54234.pdf

Seasonal evolution of the nutrient pattern on Biscay Bay continental shelf over the years 1999-2000
Provedor de dados: 5
Autores: Loyer, Sophie; Lampert, Luis; Menesguen, Alain; Cann, Philippe; Labasque, Thierry.
The French Atlantic shelf is Subjected to strong anthropic influences (urban, industrial and agricultural discharges) of two main rivers (Loire and Gironde). The extension and consequences of these continental loadings for the nutrient and chlorophyll distribution have never been studied before oil the Bay of Biscay continental shelf as a whole. We present the first synoptic view of the nutrient distribution and evolution oil the French Atlantic shelf. Nutrient concentrations of the surface layer were Studied during four cruises in April, June, September 1999 and March 2000. Until June, the freshwater inputs induce a nitrate gradient from river months to offshore waters in the vicinity of the 100 m isobath. The Redfield's ratio Study highlights the nitrate...
Tipo: Text
Palavras-chave: Nutrients; River inputs; Coastal water; Bay of Biscay.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-3956.pdf

Two- or three-layered box-models versus fine 3D models for coastal ecological modelling? A comparative study in the English Channel (Western Europe)
Provedor de dados: 5
Autores: Menesguen, Alain; Cugier, Philippe; Loyer, Sophie; Vanhoutte Brunier, Alice; Hoch, Thierry; Guillaud, Jean-francois; Gohin, Francis.
The general trend in ecosystem modelling is to improve the spatial resolution by shifting from rough box-models to fine 3D models. Despite the continuous speeding-up of computing, 3D models involving numerous state variables may remain intractable, especially for parameter calibration, when processes with long half-life periods (i.e, from years to decades) are introduced, such as the behaviour of organic matter in sediment and population dynamics of benthic species. In these cases, a first approach can be provided by fast-running box-models, if they take into account the most crucial hydrodynamic properties of the system. In a macrotidal shelf sea such as the English Channel, the long-term horizontal transport can be summarized by the tidal residual...
Tipo: Text
Palavras-chave: English Channel; Stratification; Diatom/dinoflagellate succession; 3D model; Layered box model.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2315.pdf

Modélisation de la production phytoplanctonique dans la zone côtière atlantique enrichie par les apports fluviaux
Provedor de dados: 5
Autores: Loyer, Sophie.
In order to simulate the influence of river loadings in coastal area, a three-dimensional model of primary production was set up. It is based on a hydrodynamic model previously developed at Ifremer. The calculation of the temperature and salinity takes into account the advection and the diffusion induced by tide, wind and density currents. The coupling with the biological model was done by the intermediary of transport, diffusion and heat fluxes. The cycles of three limiting elements for the phytoplankton growth were modelised : nitrogen, phosphorus and silicon. The second phase of the study aimed at reproducing the summer dinoflagellate blooms. In this new approach a model of the specie Gymnodinium mikimotoï was coupled with the previous biomass model...
Tipo: Text
Ano: 2001
URL: http://archimer.ifremer.fr/doc/2001/these-3798.pdf

Modélisation des blooms de Gymnodinium mikimotoï le long de la façade atlantique française : répartition spatiale
Provedor de dados: 5
Autores: Loyer, Sophie; Lazure, Pascal; Gentien, Patrick; Menesguen, Alain.
In order to study the occurrence of Gymnodinium mikimotoï bloom on the French Atlantic coast, a three-dimensional model of primary production was set up. The biological model was coupled to a hydrodynamic model previously developed at Ifremer, by the intermediary of transport, diffusion and heat fluxes. The cycles of three limiting elements for the phytoplankton growth were modelised: nitrogen, phosphorus and silicon. The second phase of the study aimed at reproducing the summer dinoflagellate blooms. In this new approach a model of the species Gymnodinium mikimotoï was coupled with the previous biomass model which provides the physical and chemical environments. The study focuses on the results obtained by this specific sub-model. The parametrisation was...
Tipo: Text
Palavras-chave: Turbulence; Dinoflagellés; Gymnodinium mikimotoï; Modèle; Nutriments; Turbulence; Dinoflagellate; Gymnodinium mikimotoï; Model; Nutrients.
Ano: 2001
URL: https://archimer.ifremer.fr/doc/00479/59100/61738.pdf