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| Sauzède, Raphaëlle; Martinez, Elodie; Maes, Christophe; De Fommervault, Orens Pasqueron; Poteau, Antoine; Mignot, Alexandre; Claustre, Hervé; Uitz, Julia; Oziel, Laurent; Maamaatuaiahutapu, Keitapu; Rodier, Martine; Schmechtig, Catherine; Laurent, Victoire. |
| The South Pacific Subtropical Gyre (SPSG) is a vast and remote oceanic system where the variability in phytoplankton biomass and production is still largely uncertain due to the lack of in situ biogeochemical observations. The SPSG is an oligotrophic environment where the ecosystem is controlled predominantly by nutrient depletion in surface waters. However, this dynamic is altered in the vicinity of islands where increased biological activity occurs (i.e. the island mass effect, IME). This study mainly focuses on in situ observations which show evidence of an IME leeward of Tahiti (17.7°S - 149.5°W), French Polynesia. Physical and biogeochemical observations collected with two Biogeochemical-Argo profiling floats are used to investigate the dynamics of... |
| Tipo: Text |
Palavras-chave: Phytoplankton biomass; Biogeochemical-Argo floats; Island mass effect; South Pacific Subtropical Gyre. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00599/71130/69445.pdf |
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| Sauzède, Raphaëlle; Martinez, Elodie; Pasqueron De Fommervault, Orens; Poteau, Antoine; Mignot, Alexandre; Maes, Christophe; Claustre, Hervé; Uitz, Julia; Maamaatuaiahutapu, Keitapu; Rodier, Martine; Schmechtig, Catherine; Laurent, Victoire. |
| The South Pacific Subtropical Gyre (SPSG) is a vast and remote area where large uncertainties on variability in phytoplankton biomass and production remain due to the lack of biogeochemical in situ observations. In such oligotrophic environments, ecosystems are predominantly controlled by nutrients depletion in surface waters. However, this oligotrophic character can be disturbed in the vicinity of islands where enhancement of biological activity is known to occur (i.e. the island mass effect, IME). This study mainly focuses on in situ observations showing that an IME can be evidenced leeward of Tahiti (17.7° S–149.5° W), French Polynesia. Concomitant physical and biogeochemical observations collected with two Biogeochemical-Argo (BGC-Argo) profiling... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00421/53295/54108.pdf |
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| Raapoto, Hirohiti; Martinez, Elodie; Petrenko, Anne; Doglioli, Andrea; Gorgues, Thomas; Sauzède, Raphaëlle; Maamaatuaiahutapu, Keitapu; Maes, Christophe; Menkes, Christophe; Lefèvre, Jérôme. |
| A remarkable chlorophyll‐a concentration (Chl, a proxy of phytoplankton biomass) plume can be noticed on remotely sensed ocean color observations at the boundary separating the equatorial mesotrophic from the subtropical oligotrophic waters in the central South Pacific Ocean. This prominent biological feature is known as the island mass effect of the Marquesas archipelago. Waters surrounding these islands present high macronutrient concentrations but an iron depletion. In this study, the origin of Chl enhancement is investigated using a modeling approach. Four simulations based on identical physical and biogeochemical forcings but with different iron sources are conducted and analyzed. Only simulations considering an iron input from the island sediments... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00592/70397/68481.pdf |
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| Maamaatuaiahutapu, Keitapu; Garcon, Véronique; Provost, Christine; Mercier, Herle. |
| Geostrophic transports of the western boundary currents at the Brazil/Malvinas Confluence in the South Atlantic Ocean are estimated from the data set of the Confluence 3 cruise (February 1990) with a nonlinear inverse model which takes into consideration density, current meter and wind data, and dynamical (planetary vorticity, Ekman, mass conservation) constraints. Inversions are carried out with two initial different levels of no motion at 1500 m (Case A) and at 3000 m (Case B). Consistencies of the water volume transports provided by both inversions are analyzed and compared to previous estimates. Current meter constraints are applied in the Malvinas Current region where a total transport of 45 +/- 7 Sv (1 Sv = 10(6) m(3) s(-1)) is given by both... |
| Tipo: Text |
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| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00447/55898/57923.pdf |
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