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| Lo Monaco, C.; Metzl, N.; D'Ovidio, F.; Llort, J.; Ridame, C.. |
| Iron and light are the main factors limiting the biological pump of CO2 in the Southern Ocean. Iron fertilization experiments have demonstrated the potential for increased uptake of atmospheric CO2, but little is known about the evolution of fertilized environnements. This paper presents observations collected in one of the largest phytoplankton bloom of the Southern Ocean sustained by iron originating from the Kerguelen Plateau. We first complement previous studies by investigating the mechanisms that control air–sea CO2 fluxes over and downstream of the Kerguelen Plateau at the onset of the bloom based on measurements obtained in October–November 2011. These new observations show the rapid establishment of a strong CO2 sink in waters fertilized with iron... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00295/40611/39555.pdf |
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| Sanial, V.; Van Beek, P.; Lansard, B.; Souhaut, M.; Kestenare, E.; D'Ovidio, F.; Zhou, M.; Blain, S.. |
| The Southern Ocean is known to be the largest high-nutrient, low-chlorophyll (HNLC) region of the global ocean due to iron limitation. However, a large phytoplankton bloom develops annually downstream of the Kerguelen Islands, a bloom which is sustained partly by iron released from the sediments deposited onto the shelves. In the framework of the KEOPS-2 project, we used radium isotopes (Ra-224, T-1/2 = 3.66 d; Ra-223, T-1/2 = 11.4 d; Ra-228, T-1/2 = 5.75 yr) to provide information on the origin of iron fertilization and on the timescales of the transfer of sedimentderived inputs (including iron and other micronutrients) towards offshore waters. Significant Ra-224 and Ra-223 activities were found in the near vicinity of the Kerguelen Islands, in agreement... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00291/40256/39575.pdf |
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| Merlivat, L.; Boutin, J.; D'Ovidio, F.. |
| The Kerguelen Plateau region in the Indian sector of the Southern Ocean supports annually a large-scale phytoplankton bloom which is naturally fertilized with iron. As part of the second Kerguelen Ocean and Plateau compared Study expedition (KEOPS2) in austral spring (OctoberNovember 2011), one CARbon Interface OCean Atmosphere (CARIOCA) buoy was deployed east of the Kerguelen Plateau. It drifted eastward downstream along the Kerguelen plume. Hourly surface measurements of pCO(2), O-2 and ancillary observations were collected between 1 November 2011 and 12 February 2012 with the aim of characterizing the spatial and temporal variability of the biological net community production, NCP, downstream the Kerguelen Plateau, assessing the impact of iron-induced... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00291/40254/38633.pdf |
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| Queroue, Fabien; Sarthou, Geraldine; Planquette, Helene; Bucciarelli, Eva; Chever, Fanny; Van Der Merwe, P.; Lannuzel, Delphine; Townsend, A. T.; Cheize, Marie; Blain, S.; D'Ovidio, F.; Bowie, A. R.. |
| Dissolved Fe (dFe) concentrations were measured in the upper 1300 m of the water column in the vicinity of the Kerguelen Islands as part of the second KErguelen Ocean Plateau compared Study (KEOPS2). Concentrations ranged from 0.06 nmol L-1 in offshore, Southern Ocean waters to 3.82 nmol L-1 within Hillsborough Bay, on the north-eastern coast of the Kerguelen Islands. Direct island runoff, glacial melting and resuspended sediments were identified as important inputs of dFe that could potentially fertilise the northern part of the plateau. A significant deep dFe enrichment was observed over the plateau with dFe concentrations increasing up to 1.30 nmol L-1 close to the seafloor, probably due to sediment resuspension and pore water release. Biological uptake... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00274/38482/36942.pdf |
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| Rousselet, L.; Doglioli, A.m.; De Verneil, A.; Pietri, A.; Della Penna, A.; Berline, L.; Marrec, P.; Grégori, G.; Thyssen, M.; Carlotti, F.; Barillon, S.; Simon‐bot, F.; Bonal, M.; D'Ovidio, F.; Petrenko, A.. |
| Vertical velocities can be estimated indirectly from in situ observations by theoretical frameworks like the ω‐equation. Direct measures of vertical exchanges are challenging due to their typically ephemeral spatiotemporal scales. In this study we address this problem with an adaptive sampling strategy coupling various biophysical instruments. We analyze the 3‐D organization of a cyclonic mesoscale structure finely sampled during the OSCAHR (Observing Submesoscale Coupling At High Resolution) cruise in the Ligurian Sea during fall 2015. The observations, acquired with a Moving Vessel Profiler (MVP), highlight a subsurface low‐salinity layer (≃ 50 m), as well as rising isopycnals, generated by geostrophic cyclonic circulation, in the structure's center.... |
| Tipo: Text |
Palavras-chave: High-resolution reconstructions of 3-D fields; Vertical velocities estimated with omega-equation; Particle distribution as a tracer for vertical advection. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00490/60214/63567.pdf |
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| D'Ovidio, F.; Della Penna, A.; Trull, T. W.; Nencioli, F.; Pujol, M. -i.; Rio, M.-h; Park, Y. -h.; Cotte, C.; Zhou, M.; Blain, S.. |
| Field campaigns are instrumental in providing ground truth for understanding and modeling global ocean biogeochemical budgets. A survey however can only inspect a fraction of the global oceans, typically a region hundreds of kilometers wide for a temporal window of the order of (at most) several weeks. This spatiotemporal domain is also the one in which the mesoscale activity induces through horizontal stirring a strong variability in the biogeochemical tracers, with ephemeral, local contrasts which can easily mask the regional and seasonal gradients. Therefore, whenever local in situ measures are used to infer larger-scale budgets, one faces the challenge of identifying the mesoscale structuring effect, if not simply to filter it out. In the case of the... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00296/40722/39723.pdf |
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| Zhou, M.; Zhu, Y.; D'Ovidio, F.; Park, Y.-h.; Durand, I.; Kestenare, E.; Sanial, V.; Van-beek, P.; Queguiner, B.; Carlotti, F.; Blain, S.. |
| Mean currents, horizontal diffusivity and upwelling on the Kerguelen Plateau and the deep basin east of the Kerguelen Islands were studied using 48 World Ocean Circulation Experiment (WOCE) Standard Surface Velocity Program (SVP) drifters deployed during the 2011 austral spring KEOPS II (KErguelen Ocean Plateau compared Study II) cruise. These drifter data were analyzed based on autocovariances for temporal scales, least-squares fitted streamfunctions for estimating mesoscale mean currents, wind stress fields and Ekman pumping, and Taylor's single particle diffusivity for estimating horizontal dispersion of surface waters. The results have revealed the shelfbreak current on the southern and eastern shelf slopes of the Kerguelen Islands, transport of... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00295/40621/39568.pdf |
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