Virginie Lafon

Virginie Lafon
I-SEA, France · Space oceanography

PhD

About

83
Publications
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1,209
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Publications

Publications (83)
Article
The study of the changes in swell properties in the nearshore domain due to interaction with the sea-bottom to infer the bathymetry has deserved some attention in the last few years. Satellite Remote Sensing images, in particular Synthetic Aperture Radar (SAR), have been used to produce a directional wave spectrum by Fast Fourier Transform (FFT), f...
Conference Paper
Full-text available
Fronts, which are sharp boundaries between distinct water masses, play a substantial role in managing biodiversity of marine species and preserving a resilient ecosystem. The overarching aim of this study is to compare different methodologies for detecting marine fronts. Many marine fronts are identifiable by their strong temperature gradient. For...
Article
Full-text available
The accurate measurement of suspended particulate matter (SPM) concentrations in coastal waters is of crucial importance for ecosystem studies, sediment transport monitoring, and assessment of anthropogenic impacts in the coastal ocean. Ocean color remote sensing is an efficient tool to monitor SPM spatio-temporal variability in coastal waters. How...
Article
In this paper, we explore the potentialities of using wavelet-based multivariate models for the classification of very high resolution optical images. A strategy is proposed to apply these models in a supervised classification framework. This strategy includes a content-based image retrieval analysis applied on a texture database prior to the class...
Article
Full-text available
At the end of the SPOT4 mission, a four-month experiment was conducted in 2013 to acquire high spatial (20 m) and high temporal (5 days) resolution satellite data. In addition to the SPOT4 (Take5) dataset, we used several Landsat5, 7, 8 images to document the variations in suspended particulate matter (SPM) concentration in the turbid Gironde and L...
Article
Full-text available
Classification of oyster habitats by combining wavelet-based texture features and polarimetric SAR descrip-tors. ABSTRACT In this study, we propose to evaluate the potential of combining very high resolution optical and SAR images for the classification of oyster habitats in tidal flats. To describe the classes of interest in both data, features ar...
Conference Paper
Los ecosistemas costeros son zonas de transición que se caracterizan por una alta productividad y biodiversidad. La degradación continua de estos hábitats naturales y las amenazas que se ciernen sobre determinadas especies constituyen una preocupación primordial de la política medioambiental. En este sentido, el uso de técnicas de teledetección en...
Article
Full-text available
A l'interface entre terre et mer, les zones humides littorales sont des environnements dont le fonctionnement écosystémique est contraint par les forçages climatiques et anthropiques. Par le biais des directives européennes et des plans de gestion, ces milieux sont suivis et cartographiés à échéance régulière dans le but d'asseoir leur état écologi...
Article
In between land and ocean, tidal flats and coastal wetlands functioning and evolution are constrained by climatic and anthropic-driven forces. Monitoring of these coastal areas takes place in the frame of European environmental directives and integrated management plans aiming at addressing their ecological status. Several satellite image-based map...
Conference Paper
Full-text available
This study evaluates the potential of wavelet-based texture multivariate modeling for the detection of cultivated oyster fields and their differentiation from abandoned fields in Very High Resolution panchromatic PLEIADES data. The proposed models are tested in a supervised classification context using a training database composed of extracted imag...
Article
Le Bassin d'Arcachon est caractérisé par des surfaces intertidales importantes (115 km² au total) qui sont colonisées en grande partie par des herbiers à zostères (Zostera noltii). L'enveloppe globale des herbiers constitue un indicateur de l'état écologique des eaux du bassin au sens de la Directive Cadre sur l'Eau (DCE). Elle est donc régulièreme...
Article
Le long des côtes, les fonds sableux se déplacent au gré des houles et des courants. Or, les sondages sont irréalisables sur les hauts fonds comme dans les passes d'entrée du Bassin d'Arcachon, qui sont particulièrement dangereuses pour la navigation. Une méthode basée sur l'exploitation de scènes satellites à haute résolution spatiale (Spot) a été...
Poster
Full-text available
Journée du 9 octobre 2013 ”Connaître et comprendre l’espace terre mer : l’apport de l’Ortho littorale” - Grande Arche de la Défense - Paris (MEDDE, Geolittoral) Réalisation d’un poster illustrant l’utilisation des ortho-photos littorales 2000 comme support à la cartographie des habitats marins dans le cadre du marché avec l’Agence des Aires Marines...
Article
Full-text available
This work presents preliminary results about the use of TerraSAR-X imagery for mapping intertidal habitats (oyster parks, seagrass meadows of Zostera noltii, sediments) along coastal lagoons (Arcachon lagoon, France). The combination of SAR and optical data appears to be useful to improve the discrimination of the various sediment and vegetation co...
Conference Paper
Full-text available
This contribution explores the potential of high-resolution satellite SAR imagery (TerraSAR-X, ALOS-PALSAR) for mapping coastal habitats in complement of optical data (SPOT-5). It addresses X- and L-band SAR signatures over intertidal flats and coastal salt-marshes by investigating the mean backscattering coefficient �0 over the major environmental...
Conference Paper
Full-text available
This paper presents the hyperspectral field measurements acquired at Arcachon (France) over sediments and vegetation species characteristic of the macrotidal lagoon. The reflectance spectra are analyzed to define the variables of interest in or der to propose a classification scheme useful for management purposes. The main results show that couplin...
Conference Paper
Full-text available
10.5150/jngcgc.2012.093-C © Editions Paralia CFL disponible en ligne – http://www.paralia.fr – available online Cartographie des habitats intertidaux des sites Natura 2000 des Pertuis charentais : complémentarité des approches inventaire terrain, télédétection et SIG Résumé : A la demande de l'Agence des Aires Marines Protégées, un inventaire carto...
Conference Paper
Full-text available
L’imagerie satellitaire optique dispose d’un bon potentiel de cartographie des espaces naturels littoraux de par l’emprise spatiale, la haute résolution et le recul temporel qu’offrent les 25 ans d’archives image SPOT. Cet article explore le potentiel des images SAR (Synthetic Aperture Radar) Haute Résolution (HR) pour la cartographie des habitats...
Article
Full-text available
Une série d’images satellitaires Spot couvrant la période 1997-2009 (base Kalideos Littoral) est exploitée dans l’optique de caractériser l’évolution interannuelle du littoral sableux au sud du Bassin d’Arcachon. Un algorithme semi-analytique reposant sur les propriétés optiques des eaux et des petits fonds a été calibré et validé par des données i...
Article
Full-text available
Measurements of carbon dioxide fluxes were performed over a temperate intertidal mudflat in southwestern France using the micrometeorological Eddy Covariance (EC) technique. EC measurements were carried out in two contrasting sites of the Arcachon flat during four periods and in three different seasons (autumn 2007, summer 2008, autumn 2008 and spr...
Article
Full-text available
A timeseries of Spot satellite images spanning over the 1997-2009 period (Kalideos Littoral database) is used to monitor the year-to-year evolution of the sandy stretch of coastline located south the Arcachon Lagoon. A semi-analytical algorithm based on the seawater and seabed optical properties has been calibrated and validated with in situ data a...
Article
Along sandy coasts, the bottom morphology changes as a function of waves and currents forcing parameters. The sandy shoals located at the entrance of the Arcachon Bay are particularly mobile. Their constantly changing position drastically affects the coastal shipping security. Since hydrographic surveys are impracticable over these shoals, an alter...
Article
Full-text available
The Arcachon bay is characterised by extensive intertidal flats (115 km 2 altogether) that are widely colonised by Zostera noltii meadows. The meadow cover constitutes an index of the lagoon water ecological status of the Water Framework Directive (WFD). Thus, the seagrass meadows are regularly mapped. Zostera noltii meadows show seasonal (spring a...
Article
Full-text available
Measurements of carbon dioxide fluxes were performed over a temperate intertidal mudflat in southwestern France using the micrometeorological Eddy Correlation (EC) technique. EC measurements were carried out in two contrasting sites of the Arcachon lagoon during four periods and in three different seasons (autumn 2007, summer 2008, autumn 2008 and...
Article
Full-text available
The Marennes-Oléron Bay, hosting the largest oyster production in France, is influenced by the historic polymetallic pollution of the Gironde Estuary. Despite management efforts and decreasing emissions in the Gironde watershed, cadmium levels in oysters from the bay are close to the consumption limit (5 μg g(-1) dw, EC). From mid April to mid July...
Article
Full-text available
Résumé : La gestion environnementale du Bassin d'Arcachon nécessite de disposer d'outils de suivi opérationnels d'indicateurs de qualité des milieux. L'ostréiculture, activité économique dominante après le tourisme, est implantée sur le Domaine Public Maritime sous forme de concessions qui, lorsqu'elles sont en activité, sont bien entretenues. Cepe...
Article
Historical shoreline oscillations along adjacent beaches south the Arcachon tidal inlet (south-west France) have been directly controled by sediment inputs carried through the inlet by the littoral drift. In parallell, field observations aiming at understanding high frequency processes governing short-term beach morphodynamics are conducted on a ve...
Data
Full-text available
Main objectives of this paper are to evaluate SeaWiFS, MODIS, and AVHRR satellite imagery performances against in situ data around two Northeast Atlantic seamounts, Sedlo and Seine. The temporal and spatial variability of satellite-derived near-surface chlorophyll a (Chl a) and sea surface temperature (SST) is also analysed. SeaWiFS tends to show g...
Article
Full-text available
Main objectives of this paper are to evaluate SeaWiFS, MODIS, and AVHRR satellite imagery performances against in situ data around two Northeast Atlantic seamounts, Sedlo and Seine. The temporal and spatial variability of satellite-derived near-surface chlorophyll a (Chl a) and sea surface temperature (SST) is also analysed. SeaWiFS tends to show g...
Article
Specimens of the hydrothermal mussel Bathymodiolus azoricus collected in Menez Gwen hydrothermal vent field (NE Atlantic) during 2002–2003 were examined for feeding patterns variations through three seasons. The fatty acid profile and lipid classes of the mussels were studied, together with the MODIS/AQUA-derived near-surface chlorophyll a to test...
Conference Paper
Full-text available
Alors que le fonctionnement hydro-sédimentaire des plages aquitaines est relativement bien documenté, celui du littoral sud-gironde est singulier de part sa localisation en aval de l’embouchure du Bassin d’Arcachon, soumise à l’action des courants de marée et des houles océaniques. L’évolution annuelle à décennale de ces plages est reconstituée à p...
Article
Full-text available
This study presents the first results of an ongoing research program that aims to derive thematic maps of the intertidal lagoon of Arcachon (SW Atlantic coast of
Article
Full-text available
In situ reflectance spectra have been measured during the international field experiment ECORS-Truc Vert 2008 (SW France) in the nearshore zone over a complex bathymetry and in moderately turbid waters (SPM <10 mg/l). Measurements of the atmospheric downwelling irradiance (Ed) and in-water upwelling radiance (Lu) were realized on board a jet-ski wi...
Article
In order to provide information on the production and the distribution of hydrothermal particulate and biological material produced by deep-sea hydrothermal vents, three moorings with sediment traps and currentmeters were deployed for one year in the Azores Triple Junction region. Two moorings were positioned close to two hydrothermal vent fields a...
Poster
Full-text available
SPATIO-TEMPORAL NICHE SEGREGATION BETWEEN TWO SYMPATRIC SPECIES OF DOLPHINS IN THE AZORES
Conference Paper
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This contribution presents the results of intensive field surveys executed during late spring and summer 2004 along two pocket beaches located in the northwestern and eastern coast of the Faial island (Azores archipelago, Portugal). The main purpose of this study was to characterize the morphodynamics of these two beaches by associating the short-t...
Article
The morphology and migration of rhythmic intertidal ridge and runnel systems, and subtidal crescentic bars that border the southwest coast of France were characterized using in situ surveys and maps obtained by remote-sensing methods. The period from 1986 to 2000 was investigated. A total of 35 km of coast was mapped. This data set shows several sp...
Poster
Full-text available
The Azores archipelago exhibits a particular physiography, with lack of continental shelf and presence of great heterogeneity of topographic features as submarine canyons and scattered seamounts. Patterns of distribution of bottlenose dolphins and sperm whales were evaluated with respect to two physiographic variables, water depth and sea-bottom sl...
Conference Paper
Full-text available
Using 1.1 km resolution imagery from NOAA-12, -14, -16, and -17 recorded from April 2001 to May 2003 by “HAZO” HRTP mid-Atlantic satellite receiving station, 8-day average image are calculated to investigate AVHRR-derived SST distributions and associated dominant space and time scales around the Azores archipelago (34o to 42o N, 33o to 23o W). Eigh...
Conference Paper
Full-text available
SST spatial variability in the Azores region is investigated using a method of least-square fit of a spatially averaged seasonal curve to monthly mean temperature variability curves at each pixel. The zero-order coefficient of the least-square fit is considered to represent a stationary anomaly field over the Azores region. The anomaly field reflec...
Conference Paper
Full-text available
Ocean Colour (OC) sensors have been primarily used in biological studies. More recently, OC information has been attracting the attention of oceanographers, as a potential method for revealing physical structures in the ocean. In this study, OC data obtained from SeaWiFS imagery is used, for the first time, to detect the weak Azores Current (AzC) a...
Article
This paper presents a new method to analyze the morphology and migration of shallow water sandbanks based on the retrieval of maps from high-resolution Spot satellite imagery. This approach was applied to the study of intertidal ridge and runnel systems and subtidal crescents that border the southwest coast of France. Maps were obtained from 16 Spo...
Article
Full-text available
2004. Sea surface temperature distribution in the Azores region. Part I: AVHRR imagery and in situ data processing. Arquipélago. Life and Marine Sciences 21A: 1-18. Sixteen months of 1.1 km resolution NOAA-12, -14, and -16 data for the Azores region are investigated. Advanced Very High Resolution Radiometer (AVHRR) derived sea surface temperature (...
Article
Full-text available
2004. Sea surface temperature distribution in the Azores region. Part II: space-time variability and underlying mechanisms. Arquipélago. Life and Marine Sciences 21A: 19-32. Following the methodology described in the first part of the article, monthly Sea Surface Temperature (SST) distribution and variability in the Azores region was studied for th...
Article
Full-text available
Since 4th April 2001, Sea Surface Temperature (SST) of Azorean waters is obtained from 1.1 km resolution NOAA- 12, -14, and -16 imagery recorded at the "HAZO" HRTP mid-Atlantic satellite receiving station. One year of data is processed to investigate AVHRR-derived SST distributions and associated dominant space and time scales. Daily SST is calcula...
Article
Full-text available
The Aquitanian coast (France) is representative of sandy coastal environments with long linear beaches boarding a large continental shelf and interrupted by the Gironde estuary and the Arca- chon inlet. It is a mixed-energy environment with meso-tidal and long swell influences. In order to monitor the hydro and morphodynamics of this environment, s...
Conference Paper
ONERA, the French aerospace research agency, has developed a multi-frequency, full polarimetric and high resolution airborne SAR facility named RAMSES, which has been expanded with a P-band (435 MHz) capability at the end of year 2000. The Gironde area was chosen as a suitable test-site for fieldwork validation of P-band capabilities in coordinatio...
Book
ONERA, the French aerospace research agency, has developed a multi-frequency, full polarimetric and high resolution airborne SAR facility named RAMSES, which has been expanded with a P-band (435 MHz) capability at the end of year 2000. The Gironde area was chosen as a suitable test-site for fieldwork validation of P-band capabilities in coordinatio...