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| Rintz, Cam Ly. |
| The lagoon of New Caledonia is subject to various pressures, including terrigenous stream inputs. Their evolution – extent, intensity – can be studied through parameters such as ocean color, depending on turbidity or phytoplankton concentration. Satellite imagery is more and more used for this purpose. As the Sentinel-2 (S2) mission, with its satellites providing ten meters-resolution images, has been recently launched, we worked on the characterisation of lagoon color using these products. After testing the performance of existing algorithms for New Caledonia, initially applied to satellites other than S2, we tried to establish a new turbidity algorithm based on field data (measures in the South-West lagoon of New Caledonia and the lagoon near Koumac in... |
| Tipo: Text |
Palavras-chave: Couleur de l’eau; Turbidité; Satellite; Télédétection; Réflectance; Lagon; Nouvelle-Calédonie; Sentinel-2. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00645/75752/76712.pdf |
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| Brisset, Maele; Van Wynsberge, Simon; Andréfouët, Serge; Payri, Claude; Soulard, Benoit; Bourassin, Emmanuel; Le Gendre, Romain; Coutures, Emmanuel. |
| Despite the necessary trade-offs between spatial and temporal resolution, remote sensing is an effective approach to monitor macroalgae blooms, understand their origins and anticipate their developments. Monitoring of small tropical lagoons is challenging because they require high resolutions. Since 2017, the Sentinel-2 satellites has provided new perspectives, and the feasibility of monitoring green algae blooms was investigated in this study. In the Poé-Gouaro-Déva lagoon, New Caledonia, recent Ulva blooms are the cause of significant nuisances when beaching. Spectral indices using the blue and green spectral bands were confronted with field observations of algal abundances using images concurrent with fieldwork. Depending on seabed compositions and... |
| Tipo: Text |
Palavras-chave: Ulva; Sentinel-2; Satellite; Remote sensing; Algal bloom; Coral reefs; Pacific lagoons. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00668/77968/80184.pdf |
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| ANDRADE, C. C. de; FIDALGO, E. C. C.; FRANCISCO, C. N.. |
| Este trabalho foi desenvolvido com o objetivo de mapear o uso e cobertura da terra na região de Nova Canaã, Mato Grosso, MT, visando identificar padrões para o reconhecimento de sistemas de produção existentes nas áreas agropecuárias. Para tal, foi utilizada a série temporal do período entre 2017 e 2018 das imagens do sensor Sentinel-2, com resolução espacial de 10 metros. Foram empregadas técnicas de análise baseada em objetos e mineração de dados, devido à grande quantidade de dados a serem processados e analisados. Como resultado, foi possível diferenciar as classes de uso e cobertura da terra: agricultura (dois diferentes padrões), pastagem, vegetação natural e água, com exatidão global de mapeamento de 73,5% e estatística Kappa de 0,62. A metodologia... |
| Tipo: Folhetos |
Palavras-chave: Análise de imagem baseada em objetos; Sentinel-2; Sensoriamento Remoto; Uso da Terra; Sistema de Produção; Remote sensing; Land use. |
| Ano: 2020 |
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/1123475 |
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| Yurovskaya, Maria; Kudryavtsev, Vladimir; Chapron, Bertrand; Collard, Fabrice. |
| The Sentinel-2 MultiSpectral Instrument (MSI) collects multiple spectral band images, corresponding to specific sensing wavelengths and spatial resolutions, i.e. 10 m, 20 m and 60 m, respectively. Images are collected one at the time with a given time-lag between observations. Under favorable conditions, spatio-temporal characteristics of propagating ocean surface waves can thus uniquely be retrieved. A method for surface current vector field reconstruction is then developed. Demonstrated over different deep ocean regions, the retrieved surface current fields well compare with medium-resolution ocean circulation model or derived-velocities from altimeter measurements. At finer scales, the surface wave-conservation law is recovered, with the associated... |
| Tipo: Text |
Palavras-chave: Ocean currents; Sea surface optical images; Wave dispersion relation; Time lag; Wave breaking; Sentinel-2; Satellite methods. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00587/69865/67918.pdf |
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