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| Thyssen, M.; Alvain, S.; Lefebvre, Alain; Dessailly, D.; Rijkeboer, M.; Guiselin, N.; Creach, V.; Artigas, L-f. |
| Phytoplankton observation in the ocean can be a challenge in oceanography. Accurate estimations of its biomass and dynamics will help to understand ocean ecosystems and refine global climate models. Relevant data sets of phytoplankton defined at a functional level and on a submeso- and daily scale are thus required. In order to achieve this, an automated, high-frequency, dedicated scanning flow cytometer (SFC, Cytobuoy b.v., the Netherlands) has been developed to cover the entire size range of phytoplankton cells whilst simultaneously taking pictures of the largest of them. This cytometer was directly connected to the water inlet of a PocketFerryBox during a cruise in the North Sea, 08-12 May 2011 (DYMAPHY project, INTERREG IV A "2 Seas"), in order to... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00471/58256/60766.pdf |
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| Alvain, S.; Loisel, H.; Dessailly, D.. |
| Past years have seen the development of different approaches to detect phytoplankton groups from space. One of these methods, the PHYSAT one, is empirically based on reflectance anomalies. Despite observations in good agreement with in situ measurements, the underlying theoretical explanation of the method is still missing and needed by the ocean color community as it prevents improvements of the methods and characterization of uncertainties on the inversed products. In this study, radiative transfer simulations are used in addition to in situ measurements to understand the organization of the signals used in PHYSAT. Sensitivity analyses are performed to assess the impact of the variability of the following three parameters on the reflectance anomalies:... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00661/77339/78769.pdf |
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| Masotti, I.; Belviso, S.; Alvain, S.; Johnson, J. E.; Bates, T. S.; Tortell, P. D.; Kasamatsu, N.; Mongin, M.; Marandino, C. A.; Saltzman, E. S.; Moulin, C.. |
| Dimethylsulfoniopropionate (DMSP) is produced in surface seawater by phytoplankton. Phytoplankton culture experiments have shown that nanoeucaryotes (NANO) display much higher mean DMSP-to-Carbon or DMSP-to-Chlorophyll (Chl) ratios than Prochlorococcus (PRO), Synechococcus (SYN) or diatoms (DIAT). Moreover, the DMSP-lyase activity of algae which cleaves DMSP into dimethylsulfide (DMS) is even more group specific than DMSP itself. Ship-based observations have shown at limited spatial scales, that sea surface DMS-to-Chl ratios (DMS: Chl) are dependent on the composition of phytoplankton groups. Here we use satellite remote sensing of Chl (from SeaWiFS) and of Phytoplankton Group Dominance (PGD from PHYSAT) with ship-based sea surface DMS concentrations (8... |
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| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00231/34250/32617.pdf |
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| Arnold, S. R.; Spracklen, D. V.; Williams, J.; Yassaa, N.; Sciare, J.; Bonsang, B.; Gros, V.; Peeken, I.; Lewis, A. C.; Alvain, S.; Moulin, C.. |
| We have combined the first satellite maps of the global distribution of phytoplankton functional type and new measurements of phytoplankton-specific isoprene productivities, with available remote marine isoprene observations and a global model, to evaluate our understanding of the marine isoprene source and its impacts on organic aerosol abundances. Using satellite products to scale up data on phytoplankton-specific isoprene productivity to the global oceans, we infer a mean "bottom-up" oceanic isoprene emission of 0.31 +/- 0.08 (1 sigma) Tg/yr. By minimising the mean bias between the model and isoprene observations in the marine atmosphere remote from the continents, we produce a "top-down" oceanic isoprene source estimate of 1.9 Tg/yr. We suggest our... |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32915/31411.pdf |
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