Добірка наукової літератури з теми "Phytoplancton marin – Télédétection – Sénégal"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Phytoplancton marin – Télédétection – Sénégal".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Дисертації з теми "Phytoplancton marin – Télédétection – Sénégal":
Correa, Khassoum. "Réponse des groupes fonctionnels de phytoplancton à la dynamique du plateau sénégalais." Electronic Thesis or Diss., Brest, 2023. http://theses-scd.univ-brest.fr/2023/These-2023-SML-Oceanographie_physique_et_environnement-CORREA_Khassoum.pdf.
Water color sensors measure upward radiation that includes contributions from the sea and atmosphere. We have adapted an atmospheric correction algorithm, SOM-NV, to raw observations from the MODIS-Aqua sensor over the West African ocean region, to generate aerosol and water properties simultaneously. The observed optical thickness values are better represented by SOM-NV processing than by standard MODIS (STD). At the same time, SOM-NV marine reflectances (Rrs) are more consistent with signal theory than STD Rrs. SOM-NV improves coverage by up to 35% at certain times of the year. Coverage is best at the coast and south of Cape Verde. Observations in Chla show coastal maxima that extend offshore according to season and latitude. The region is marked by alternating classes of reflectance anomaly that characterize phytoplankton communities. Most classes are associated with pigment mixtures characteristic of functional groups. An algal class close to brown algae and another to green algae dominate in autumn and early winter. From February to May, brown algae classes are very present and associated with high biomass. They alternate with a mixed class associated with the pigments fucoxanthin 19'HF and chlorophyll-b. This class seems to be favored when biomasses are lower
Rêve-Lamarche, Anne-Hélène. "Vers l’identification d’assemblages phytoplanctoniques depuis l’espace à travers le couplage innovant d’analyses des radiances et de données in-situ : perspectives pour l’étude des habitats et des réponses des assemblages." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R076.
Over the past years, a large number of new approaches in the domain of ocean-color have been developed to study phytoplankton ocean processes based on phytoplankton size classes and functional types. One of these methods, named PHYSAT, currently allows for the qualitative detection of five main phytoplankton groups from ocean-color measurements (Alvain et al., 2008). This method established empirical relationships between in-situ dominant phytoplankton groups and specific ocean-color radiance anomalies in open ocean waters. These radiance anomalies are defined by specific shape and amplitude according to the dominant phytoplankton group in waters. The theoretical explanation of PHYSAT (Alvain et al., 2012) showed that radiance anomalies are induced by a combination of inherent optical properties; and this study suggested that the detection of dominant cases represents an under-exploitation of the radiance anomalies. The work presented here addresses the potential development of the PHYSAT method toward the detection of phytoplankton assemblages. A global ocean (based on biomarker pigments data) and a regional sea’s (North Sea, based on CPR data) applications are presented. Our results show, for the first time, the ability of PHYSAT to detect phytoplankton assemblages using empirical relationships with radiance anomalies, beyond the detection of dominance cases only. This work was facilitated by the use of previous classification of radiance anomalies in terms of shape and amplitude (using a self-organizing map, Ben Mustapha et al. (2014), coupled with a new classification that take into account the phenology of radiance anomalies classes. This work emphases the potential of PHYSAT’s radiance anomalies when using new classification tools, and detailed in-situ databases. Future directions are listed to understand the empirical relationships observed in this work beyond the current theoretical knowledge
Rêve-Lamarche, Anne-Hélène. "Vers l’identification d’assemblages phytoplanctoniques depuis l’espace à travers le couplage innovant d’analyses des radiances et de données in-situ : perspectives pour l’étude des habitats et des réponses des assemblages." Electronic Thesis or Diss., Université de Lille (2018-2021), 2018. http://www.theses.fr/2018LILUR076.
Over the past years, a large number of new approaches in the domain of ocean-color have been developed to study phytoplankton ocean processes based on phytoplankton size classes and functional types. One of these methods, named PHYSAT, currently allows for the qualitative detection of five main phytoplankton groups from ocean-color measurements (Alvain et al., 2008). This method established empirical relationships between in-situ dominant phytoplankton groups and specific ocean-color radiance anomalies in open ocean waters. These radiance anomalies are defined by specific shape and amplitude according to the dominant phytoplankton group in waters. The theoretical explanation of PHYSAT (Alvain et al., 2012) showed that radiance anomalies are induced by a combination of inherent optical properties; and this study suggested that the detection of dominant cases represents an under-exploitation of the radiance anomalies. The work presented here addresses the potential development of the PHYSAT method toward the detection of phytoplankton assemblages. A global ocean (based on biomarker pigments data) and a regional sea’s (North Sea, based on CPR data) applications are presented. Our results show, for the first time, the ability of PHYSAT to detect phytoplankton assemblages using empirical relationships with radiance anomalies, beyond the detection of dominance cases only. This work was facilitated by the use of previous classification of radiance anomalies in terms of shape and amplitude (using a self-organizing map, Ben Mustapha et al. (2014), coupled with a new classification that take into account the phenology of radiance anomalies classes. This work emphases the potential of PHYSAT’s radiance anomalies when using new classification tools, and detailed in-situ databases. Future directions are listed to understand the empirical relationships observed in this work beyond the current theoretical knowledge
El, Hourany Roy. "Télédétection du phytoplancton par méthode neuronale : du global au régional, de la composition pigmentaire aux biorégions." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS095.
This thesis presents a novel approach to analyze and observe the phytoplankton community structure at global and regional scale using satellite data (Ocean colour and Sea surface temperature) and in-situ observations. The approach is based on neural network classification methods, such as Self-Organizing Maps (SOM) trained on a large global database composed of satellite observations collocated with in-situ measurements. First, we developed a method to estimate secondary phytoplankton pigments from satellite measurements in the global ocean. Then we focused our studies on the Mediterranean Sea. Phytoplankton groups (PFTs) were identified from the secondary pigments estimated in the first phase. We then characterized seven bio-regions by clustering annual cycles MLD obtained from Argo floats, SST and Chla by using an advanced SOM. At last, these bio-regions were characterized in terms of PFTs. The methods developed in this thesis allowed us to estimate uncertainties on secondary pigments and PFTs. The applicability of these methods are broad and can be used to investigate other oceanic areas
Mélin, Frédéric. "Potentiel de la télédétection pour l'analyse des propriétés optiques du système océan-atmosphère et application à l'estimation de la photosynthèse phytoplanctonique." Toulouse 3, 2003. http://www.theses.fr/2003TOU30215.
Ben, Mustapha Zied. "Télédétection des groupes phytoplanctoniques via l'utilisation conjointe de mesures satellites, in situ et d'une méthode de classification automatique." Thesis, Littoral, 2013. http://www.theses.fr/2013DUNK0405/document.
Remote sensing of ocean color is a powerful tool for monitoring phytoplankton in the ocean with a high spatial and temporal resolution. Several methods were developed in the past years for detecting phytoplankton functional types from satellite observations. In this thesis, we present an automatic classification method, based on a neural network clustering algorithm, in order to classify the anomalies of water leaving radiances spectra (Ra), introduced in the PHYSAT method by Alvain et al. (2005) and analyze their variability at the global scale. The use of an unsupervised classification aims at improving the characterization of the spectral variability of Ra in terms of shape and amplitude as well as the expansion of its potential use to larger in situ datasets for global phytoplankton remote sensing. The Self-Organizing Map Algorithm (SOM) aggregates similar spectra into a reduced set of pertinent groups, allowing the characterization of the Ra variability, which is known to be linked with the phytoplankton community composition. Based on the same sample of Ra spectra, a comparison between the previous version of PHYSAT and the new one using SOM shows that is now possible to take into consideration all the types of spectra. This was not possible with the previous approach, based on thresholds, defined in order to avoid overlaps between the spectral signatures of each phytoplankton group. The SOM-based method is relevant for characterizing a wide variety of Ra spectra through its ability to handle large amounts of data, in addition to its statistical reliability compared to the previous PHYSAT. The former approach might have introduced potential biases and thus, its extension to larger databases was very restricted. In a second step, some new Ra spectra have been related to phytoplankton groups using collocated field pigments inventories from a large in situ database. Phytoplankton groups were identified based on biomarker pigments ratios thresholds taken from the literature. SOM was then applied to the global daily SeaWiFS imagery archive between 1997 and 2010. Global distributions of major phytoplankton groups were analyzed and validated against in situ data. Thanks to its ability to capture a wide range of spectra and to manage a larger in situ pigment dataset, the neural network tool allows to classify a much higher number of pixels (2 times more) than the previous PHYSAT method for the five phytoplankton groups taken into account in this study (Synechococcus-Like-Cyanobacteria, diatoms, Prochloroccus, Nanoeucaryots and Phaeocystis-like). In addition, different Ra spectral signatures have been associated to diatoms. These signatures are located in various environments where the inherent optical properties affecting the Ra spectra are likely to be significantly different. Local phenomena such as diatoms blooms in the upwelling regions or during climatic events(i.e. La Nina) are more clearly visible with the new method. The PHYSAT-SOM method provides several perspectives concerning the use of the ocean color remote sensing data for phytoplankton group identification, such as, the potential application of the method in Case 2 waters, using an appropriate nLw signal normalization approach. A preliminary case study in the English Channel and North Sea waters is presented in the last chapter of the thesis, showing the possibility of a future use of PHYSAT-SOM in these optically complex waters
Vantrepotte, Vincent. "Caractérisation bio-optique des eaux côtières en Manche Orientale pour l'estimation de la production primaire et le suivi des poussées phytoplanctoniques : application à la télédétection satellitaire "couleur de l'eau" en milieu côtier." Littoral, 2003. http://www.theses.fr/2003DUNK0100.
The coastal ecosystems are among the most productive but also the most variable ones at both spatial and temporal scales. Remote sensing of "ocean colour" seems to be well adapted to study phytoplankton dynamics in such variable systems, due to its high spatial resolution and high temporal frequency. Remote sensing development in coastal waters (belonging to case 2 waters) requires simultaneously the characterization of : (i) the phytoplankton dynamics, (ii) the bio-optical properties of the optically active compartments of seawater (phytoplankton, yellow substances and non-phytoplankton particulate matter) and (iii) the variability of algal photosynthetic parameters. These points correspond to the objectives of our study, for which 5 mesoscale campaigns at sea were carried out in the eastern English Channel in 2000. At an ecological point of view, various ecosystems ("province") were discriminated on their hydro-biological characteristics. At a bio-optical point of view, the absorption spectra of yellow substances, phytoplankton and non-phytoplankton particulate matter present different dynamics (both at space and season scales), related to different environmental and/or biological factors. The variability of the algal photosynthetic parameters was studied on various spatial and temporal scales in order to define and adapted strategy for the mesoscale primary production modelling in the Eastern English Channel
Bricaud-Wehrlin, Annick. "Propriétés optiques du phytoplancton : étude théorique et expérimentale : application à l'interprétation de la couleur de la mer." Paris 6, 1989. http://www.theses.fr/1989PA066074.
Mangolte, Inès. "Effet des fronts océaniques sur les communautés de plancton." Electronic Thesis or Diss., Sorbonne université, 2022. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2022SORUS489.pdf.
Oceanic fronts are transition zones between water masses with different physico-chemical properties that are associated with a very dynamic horizontal and vertical circulation. Empirical observations and modeling studies have shown that the vertical input of nutrients by the cross-frontal circulation stimulates primary production and causes an increase in the biomass of a group of opportunistic phytoplankton, the diatoms, at the fronts. However, the consequences of this nutrient input on the rest of the planktonic community are still poorly understood. In this thesis, I use both empirical data and numerical simulations to characterize the effect of fronts on the entire planktonic community, including other phytoplankton groups (such as cyanobacteria, coccolithophores and dinoflagellates) and zooplankton. The model is a simplified high-resolution representation of a Western Boundary Current (such as the Gulf Stream or the Kuroshio) coupled with the DARWIN ecosystem model, which includes 30 phytoplankton types in four functional groups and 16 zooplankton types. The empirical data was collected in the California upwelling region during transects across fronts, and consist of 24 plankton groups including heterotrophic bacteria, phytoplankton and zooplankton. I show that the taxonomic and spatial structure of planktonic frontal communities is extremely complex, and cannot be explained solely by increased growth in response to nutrient supply. Using numerical simulations, I show that two types of biotic interactions cause a decrease in the biomass of certain phytoplankton groups in fronts: self-shading, which is a form of competition for light, and shared predation, which is a form of indirect competition between two prey sharing a common predator. Using the in-situ data, I highlight two characteristics of the fronts that were absent from the numerical simulations. First, the spatial scale of planktonic community organization across fronts is much finer than previously thought: the biomass peaks of the various plankton groups are very narrow and are offset by a few kilometers from each other. This result suggests that the structure of the frontal plankton communities is strongly influenced by biotic interactions and transport. The role of transport will be explored through a collaboration on the Lagrangian trajectories of water masses. Second, fronts have a dramatic effect on some filter-feeding zooplankton organisms that are not represented in traditional plankton models, suggesting that these models will need to be made more complex in order to properly simulate the effect of fronts. Thus, the results I obtained during this thesis complement and complicate the mechanistic model established during the last two decades: far from being limited to the production of diatom blooms, fronts are the scene of complex biophysical couplings between top-down and bottom-up biotic interactions and transport by currents that generate planktonic communities with an original taxonomic and spatial structure. The modification of the structure of planktonic communities at ocean fronts could have important consequences on the upper trophic levels and on biogeochemical fluxes that will have to be clarified in the future
Danhiez, François-Pierre. "Relations entre les propriétés optiques de la matière organique dissoute colorée et le carbone organique dissous dans des eaux côtières aux caractéristiques contrastées." Thesis, Littoral, 2015. http://www.theses.fr/2015DUNK0395/document.
The coastal ocean represents an important component of the global carbon cycle however its participation to the overall carbon flux is currently not well constrained. Information on DOC stock and its variability in the coastel ocean is however still very scarce and its represents a strong limitation to our current understanding of the exact role of these ecosystems in the oceanic carbon cycle. In this context, the general aims of this study was to get more insights on dissolved organic carbon dynamics in the coastal ocean through the optical properties of dissolved organic matter (CDOM) that present the advantage to be easily measured from in situ or satellite observations. In practice, in situ data gathered during several sampling cruises conducted in three constrasted continental margins (Eastern Channel, French Guiana, Vietnam) have allowed : (i) the characterization of the strong regional discrepancies in the CDOM-DOC relationships between the three coastal sites investigated, (ii) the possible use of a generalized parameterization to retrieve DOC concentrations from CDOM optical properties (estimated in situ or from ocean color remote sensing)over a large range of coastal sites dominated by terrestrial imput of DOM. A further objective of this work was to investigate the impact on DOM dynamics of the phytoplankton bloom event of Phaeocystis.globosa known to affect the coastal waters of the eastern English Channel during the spring period. In practice, this DOM production was investigated during a 45 days mesocom experiment coupled to field survey data (2012-1014) leading to the identification of an optical marker of this marine CDOM production (i.e. S320-412). We further demonstrated that this optical parameter provides useful information to enhance our ability to retrieve DIC 1 from CDOM optical properties in a context of an algal bloom event
Книги з теми "Phytoplancton marin – Télédétection – Sénégal":
A, Borstad G., ed. Analysis of test and flight data from the fluorescence line imager. Ottawa: Dept. of Fisheries and Oceans, 1985.
A, Borstad Gary, and Canada. Department ofFisheries and Oceans., eds. Analysis of test and flight data from the Fluorescence Line Imager. Ottawa: Fisheries and Oceans, Scientific Information and Publications Branch, 1985.