|
|
|
|
|
| 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 |
| |
|
|
| 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... |
| Tipo: Text |
|
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00421/53295/54108.pdf |
| |
|
|
| 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 |
|
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00592/70397/68481.pdf |
| |
|
|
| Martinez, Elodie; Gorgues, Thomas; Lengaigne, Matthieu; Fontana, Clement; Sauzède, Raphaëlle; Menkes, Christophe; Uitz, Julia; Di Lorenzo, Emanuele; Fablet, Ronan. |
| Monitoring the spatio-temporal variations of surface chlorophyll-a concentration (Chl, a proxy of phytoplankton biomass) greatly benefited from the availability of continuous and global ocean color satellite measurements from 1997 onward. These two decades of satellite observations are however still too short to provide a comprehensive description of Chl variations at decadal to multi-decadal timescales. This paper investigates the ability of a machine learning approach (a non-linear statistical approach based on Support Vector Regression, hereafter SVR) to reconstruct global spatio-temporal Chl variations from selected surface oceanic and atmospheric physical parameters. With a limited training period (13 years), we first demonstrate that Chl variability... |
| Tipo: Text |
Palavras-chave: Machine learning; Phytoplankton variability; Satellite ocean color; Decadel variability; Global scale. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00641/75314/75810.pdf |
| |
|
|
|
