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| Levy, M.; Klein, Patrice; Ben Jelloul, M.. |
| Using an idealized model of an oligotrophic open-ocean region characterized by intense sub-mesoscale turbulence, we show that the presence of energetic near-inertial motions, forced by high-frequency winds, triggers transient nutrient inputs in the surface mixed-layer, stimulating new production. We also show that this production increase is larger than the increase due to the Ekman transport resulting from a slow-evolving wind forcing. The nutrient supplies are due to the interaction between near-inertial motions and the submesoscale frontogenetic dynamics that reinforces both the vertical advection and vertical diffusion, especially within sub-mesoscales features. The net result is an uplift of new production from the subsurface to the mixed-layer. A... |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6767.pdf |
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| Person, Roland; Aumont, Olivier; Levy, M.. |
| Iron is known to limit primary production in the Southern Ocean (SO). To cope with the lack of this micronutrient, diatoms, a dominant phytoplankton group in this oceanic region, have been shown in cultures to have developed an original adaptation strategy to maintain efficient growth rates despite very low cellular iron quotas, even in low light conditions. Using a global ocean biogeochemical model, we explored the consequences of this physiological adaptation for the biological pump and the seasonal variability of both surface chlorophyll concentrations and surface partial pressure of carbon dioxide (pCO(2)) in this key region for global climate. In the model, we implemented a low intracellular Fe:C requirement in the SO for diatoms uniquely. This... |
| Tipo: Text |
Palavras-chave: Southern Ocean; Diatoms; Physiological adaptation; Biological pump; PCO(2); Seasonal variability. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00673/78490/80817.pdf |
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| Keerthi, M. G.; Levy, M.; Aumont, Olivier; Lengaigne, Matthieu; Antoine, D.. |
| Understanding long‐term variations of ocean ecosystems requires untangling the time scales involved in their natural fluctuations. We applied a temporal decomposition procedure to two decades of satellite ocean color observations to characterize the time variability of surface Chlorophyll‐a (SChl) in the Mediterranean Sea. In order to assess the reliability of the satellite data at capturing intraseasonal, seasonal and interannual variability, we first show that satellite SChl data compare well with field data of phytoplankton fluorescence from the long‐term BOUSSOLE time series, at all three timescales. The decomposition procedure is then applied to satellite SChl and to mixing‐layer depth (MxLD) data from an ocean reanalysis, both at the scale of the... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00624/73654/73098.pdf |
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| Keerthi, M. G.; Lengaigne, M.; Drushka, K.; Vialard, J.; De Boyer Montegut, Clement; Pous, Stephane; Levy, M.; Muraleedharan, P. M.. |
| In this paper, we use an observational dataset built from Argo in situ profiles to describe the main large-scale patterns of intraseasonal mixed layer depth (MLD) variations in the Indian Ocean. An eddy permitting (0.25A degrees) regional ocean model that generally agrees well with those observed estimates is then used to investigate the mechanisms that drive MLD intraseasonal variations and to assess their potential impact on the related SST response. During summer, intraseasonal MLD variations in the Bay of Bengal and eastern equatorial Indian Ocean primarily respond to active/break convective phases of the summer monsoon. In the southern Arabian Sea, summer MLD variations are largely driven by seemingly-independent intraseasonal fluctuations of the... |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00332/44335/45788.pdf |
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