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Registros recuperados: 6
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A Statistical Algorithm for Estimating Chlorophyll Concentration in the New Caledonian Lagoon ArchiMer
Wattelez, Guillaume; Dupouy, Cecile; Mangeas, Morgan; Lefevre, Jerome; Touraivane,; Frouin, Robert.
Spatial and temporal dynamics of phytoplankton biomass and water turbidity can provide crucial information about the function, health and vulnerability of lagoon ecosystems (coral reefs, sea grasses, etc.). A statistical algorithm is proposed to estimate chlorophyll-a concentration ([chl-a]) in optically complex waters of the New Caledonian lagoon from MODIS-derived remote-sensing reflectance (R-rs). The algorithm is developed via supervised learning on match-ups gathered from 2002 to 2010. The best performance is obtained by combining two models, selected according to the ratio of R-rs in spectral bands centered on 488 and 555 nm: a log-linear model for low [chl-a] (AFLC) and a support vector machine (SVM) model or a classic model (OC3) for high [chl-a]....
Tipo: Text Palavras-chave: Chlorophyll-a concentration; MODerate resolution Imaging Spectroradiometer (MODIS); Ocean color; Remote sensing; Statistical algorithm; Oligotrophic waters; New Caledonia; Coral lagoon.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00481/59309/62060.pdf
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Bio-Optical Characterization and Ocean Colour Inversion in the Eastern Lagoon of New Caledonia, South Tropical Pacific ArchiMer
Favareto, Luciane Rafaele; Rudorff, Natalia; Kampel, Milton; Frouin, Robert; Roettgers, Ruediger; Doxaran, David; Murakami, Hiroshi; Dupouy, Cecile.
The Eastern Lagoon of New Caledonia (ELNC) is a semi-enclosed system surrounded by an extensive coral reef barrier. The system has been suffering impacts from climate variability and anthropogenic activities, including mining exploitation. Satellite monitoring is thus an essential tool to detect such changes. The present study aimed to assess the bio-optical variability of the ELNC and examine the applicability of ocean colour algorithms, using in situ bio-optical and radiometric data, collected during the March 2014 CALIOPE 2 cruise. The chlorophyll a concentration (Chla) varied from 0.13-0.72 mg.m(-3), and the coastal stations were spectrally dominated by non-algal particles (NAP) and coloured dissolved organic matter (CDOM) (>80% of the total...
Tipo: Text Palavras-chave: Marine remote sensing reflectance; Bio-optical properties; Ocean colour algorithms; Eastern lagoon of New Caledonia; Southwest Tropical Pacific Ocean.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00481/59306/62063.pdf
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Diazotrophic Trichodesmium impact on UV-Vis radiance and pigment composition in the western tropical South Pacific ArchiMer
Dupouy, Cecile; Frouin, Robert; Tedetti, Marc; Maillard, Morgane; Rodier, Martine; Lombard, Fabien; Guidi, Lionel; Picheral, Marc; Neveux, Jacques; Duhamel, Solange; Charriere, Bruno; Sempere, Richard.
We assessed the influence of the marine diazotrophic cyanobacterium Trichodesmium on the bio-optical properties of western tropical South Pacific (WTSP) waters (18-22 degrees S, 160 degrees E-160 degrees W) during the February-March 2015 OUTPACE cruise. We performed measurements of backscattering and absorption coefficients, irradiance, and radiance in the euphotic zone with a Satlantic MicroPro free-fall profiler and took Underwater Vision Profiler 5 (UPV5) pictures for counting the largest Trichodesmium spp. colonies. Pigment concentrations were determined by fluorimetry and high-performance liquid chromatography and picoplankton abundance by flow cytometry. Trichome concentration was estimated from pigment algorithms and validated by surface visual...
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Ano: 2018 URL: https://archimer.ifremer.fr/doc/00457/56824/58659.pdf
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Modelling N2 fixation related to Trichodesmium sp.: driving processes and impacts on primary production in the tropical Pacific Ocean ArchiMer
Dutheil, Cyril; Aumont, Olivier; Gorgues, Thomas; Lorrain, Anne; Bonnet, Sophie; Rodier, Martine; Dupouy, Cecile; Shiozaki, Takuhei; Menkes, Christophe.
Dinitrogen fixation is now recognized as one of the major sources of bio-available nitrogen in the ocean. Thus, N2 fixation sustains a significant part of the global primary production by supplying the most common limiting nutrient for phytoplankton growth. The Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) improved the data coverage of the western tropical South Pacific, an area recently recognized as a hotspot of N2 fixation. This new development leads us to develop and test an explicit N2 fixation formulation based on the Trichodesmium physiology (the most studied nitrogen fixer) within a 3-D coupled dynamical–biogeochemical model (ROMS-PISCES). We performed a climatological numerical simulation that is able to reproduce the main physical...
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Ano: 2018 URL: https://archimer.ifremer.fr/doc/00419/53042/53979.pdf
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Phytoplankton dynamics in the southern New Caledonian lagoon during a southeast trade winds event ArchiMer
Neveux, Jacques; Lefebvre, Jean-pierre; Le Gendre, Romain; Dupouy, Cecile; Gallois, Francis; Courties, Claude; Gerard, Philippe; Fernandez, Jean-michel; Ouillon, Sylvain.
During the Echolag cruise (13 February-8 March 2007), the effect of 16-30 knot trade winds on abundance, community structure and dynamics of phytoplankton was investigated in the southern part of the New Caledonian coral reefs and surrounding oceanic waters. In this area, the coral reefs form two horn-like structures (hereinafter referred to as 'horn reefs'), oriented south-east, and separated by a relatively deep valley. Three repeated samplings at one week intervals of a 32 station array showed that trade winds induce surface water cooling and significant enrichment of mid- and bottom waters above the reef shelf. This enrichment appeared as the result of a general rise of the oceanic thermocline and nitracline due to the combination of trade winds and...
Tipo: Text Palavras-chave: Chlorophyll; Phycoerythrin; Flow cytometry; Phytoplankton; In vivo fluorescence; Growth rate; Trade winds; Lagoon; Internal wave; New Caledonia.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00013/12437/9258.pdf
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Remote Sensing of Trichodesmium spp. mats in the Western Tropical South Pacific ArchiMer
Rousset, Guillaume; De Boissieu, Florian; Menkes, Christophe E.; Lefevre, Jerome; Frouin, Robert; Rodier, Martine; Ridoux, Vincent; Laran, Sophie; Bonnet, Sophie; Dupouy, Cecile.
Trichodesmium is the main nitrogen-fixing species in the South Pacific region, a hotspot for diazotrophy. Due to the paucity of in situ observations, methods for detecting Trichodesmium presence on a large scale have been investigated to assess the regional-to-global impact of these species on primary production and carbon cycling. A number of satellite-derived algorithms have been developed to identify Trichodesmium surface blooms, but determining with confidence their accuracy has been difficult, chiefly because of the scarcity of sea-truth information at time of satellite overpass. Here, we use a series of new cruises as well as airborne observational surveys in the South Pacific to quantify statistically the ability of these algorithms to discern...
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Ano: 2018 URL: https://archimer.ifremer.fr/doc/00419/53004/53953.pdf
Registros recuperados: 6
Primeira ... 1 ... Última
 

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