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18 results on '"Nicolas Grima"'

1. Fates of paleo Antarctic Bottom Water during the early Eocene ― based on a Lagrangian analysis of IPSL‐CM5A2 climate model simulations

Author

Nicolas Grima, Yurui Zhang, Thierry Huck, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Interdisciplinary Graduate School for the Blue planet, ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Ekman pumping, [SDE.MCG]Environmental Sciences/Global Changes, deepwater obduction, Paleontology, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Antarctic Bottom Water, 13. Climate action, Lagrangian analysis, Ekman transport, Climate model, 14. Life underwater, the early Eocene, Equtorial and tropical upwelling, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, paleo-Antarctic Bottom Water, 0105 earth and related environmental sciences
Abstract

International audience; Both deepwater formation and the obduction processes converting dense deepwater to lighter surface water are the engine for the global meridional overturning circulation (MOC). Their spatio‐temporal variations effectively modify the ocean circulation and related carbon cycle, which affects climate evolution throughout geological time. Using early‐Eocene bathymetry and enhanced atmospheric CO2 concentration, the IPSL‐CM5A2 climate model has simulated a well‐ventilated Southern Ocean associated with a strong anticlockwise MOC.To trace the fates of these paleo Antarctic Bottom Water (paleo‐AABW), we conducted Lagrangian analyses using these IPSL‐CM5A2 model results and tracking virtual particles released at the lower limb of the MOC, defined as an initial section at 60°S below 1900m depth. Diagnostic analysis of these particles trajectories reveals that most paleo‐AABW circulates back to the Southern Ocean through either the initial section (43%) or the section above (31%); the remaining (>25%) crossing the base of the mixed layer mostly in tropical regions (up to half). The majority of water parcels ending in the mixed layer experience negative density transformations, intensified in the upper 500m and mostly occurring in tropical upwelling regions, with a spatial pattern consistent with the wind‐driven Ekman pumping, largely determined by the Eocene wind stress and continental geometry.In the same way as present‐day North Atlantic Deep Water upwells in the Southern Ocean, our results suggest that the strong tropical and equatorial upwelling during the Eocene provides an efficient pathway from the abyss to the surface, but at much higher temperature, with potential implications for the oceanic carbon cycle.

Published
2021

2. Eddy properties in the Southern California Current System

Author

Peter Franks, Nicolas Grima, Vincent Combes, Xavier Capet, Pascal Rivière, Bruno Blanke, Fanny Chenillat, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Processus de couplage à Petite Echelle, Ecosystèmes et Prédateurs Supérieurs (PEPS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), California Current Ecosystem LTER site (NSFAward) grant number 1026607, CNES, Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Water exchange, Oceanography, 01 natural sciences, Mesoscale eddies, Numerical study, California upwelling system, Lagrangian coherent structures, 14. Life underwater, Lagrangian study, 0105 earth and related environmental sciences, Shore, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, Cyclonic eddies, Eddy dynamics, 010505 oceanography, ACL, Geology, Current (stream), Eddy, Upwelling, Submarine pipeline, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The California Current System (CCS) is an eastern boundary upwelling system characterized by strong eddies that are often generated at the coast. These eddies contribute to intense, long-distance cross-shelf transport of upwelled water with enhanced biological activity. However, the mechanisms of formation of such coastal eddies, and more importantly their capacity to trap and transport tracers, are poorly understood. Their unpredictability and strong dynamics leave us with an incomplete picture of the physical and biological processes at work, their effects on coastal export, lateral water exchange among eddies and their surrounding waters, and how long and how far these eddies remain coherent structures. Focusing our analysis on the southern part of the CCS, we find a predominance of cyclonic eddies, with a 25-km radius and a SSH amplitude of 6 cm. They are formed near shore and travel slightly northwest offshore for ~ 190 days at ~ 2 km day−1. We then study one particular, representative cyclonic eddy using a combined Lagrangian and Eulerian numerical approach to characterize its kinematics. Formed near shore, this eddy trapped a core made up of ~ 67% California Current waters and ~ 33% California Undercurrent waters. This core was surrounded by other waters while the eddy detached from the coast, leaving the oldest waters at the eddy’s core and the younger waters toward the edge. The eddy traveled several months as a coherent structure, with only limited lateral exchange within the eddy.

Published
2018

3. A surface 'superconvergence' pathway connecting the South Indian Ocean to the subtropical south Pacific gyre

Author

Bruno Blanke, Elodie Martinez, Christophe Maes, Nicolas Grima, Thomas Paviet-Salomon, Thierry Huck, Institut de Recherche pour le Développement (IRD), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Lab-STICC_ENSTAB_CID_TOMS, Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Lab-STICC_IMTA_CID_TOMS, Département Signal et Communications (IMT Atlantique - SC), IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)

Subjects
010504 meteorology & atmospheric sciences, Mesoscale meteorology, Subtropics, 010501 environmental sciences, Convergence zone, 01 natural sciences, Accumulation, Ocean gyre, Worlds, 14. Life underwater, 0105 earth and related environmental sciences, South Pacific Gyre, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, Sea, Ocean current, Biogeochemistry, Debris, Plastic debris, Geophysics, Oceanography, 13. Climate action, [SDU]Sciences of the Universe [physics], General Earth and Planetary Sciences, Geology, Model
Abstract

International audience; We study the dispersion and convergence of marine floating material by surface currents from a model reanalysis that represents explicitly mesoscale eddy variability. Lagrangian experiments about the long-term evolution (29 years) of an initially homogeneous concentration of particles are performed at global scale with horizontal current at one fourth degree resolution and refreshed daily over the 1985-2013 period. Results not only confirm and document the five known sites of surface convergence at the scale of individual oceanic basins but also reveal a convergent pathway connecting the South Indian subtropical region with the convergence zone of the South Pacific through the Great Australian Bight, the Tasman Sea, and the southwest Pacific Ocean. This "superconvergent" pathway at the ocean surface is robust and permanent over a distance longer than 8,000 km. The current variability is crucial to sustain this pathway.Plain Language SummaryUnderstanding the fate of marine and plastic debris at the ocean surface is an objective to be achieved before informing and discussing with policy and decision environmental makers. The transport pathways of such material need to be precisely determined to estimate the pollution at a global scale. By considering nonstationary ocean dispersion by mesoscale eddy variability, this study reveals a novel convergent zone, over a distance larger than 8,000 km, that connects the subtropical South Indian Ocean with the core of the convergent zone of the South Pacific Ocean. The existence of a "superconvergent" pathway in addition to the five convergent zones is of interest to scientists studying plastic debris and more broadly to modelers and experimentalists studying ocean physics and biogeochemistry.

Published
2018

4. Mesoscale eddy activity in the southern Benguela upwelling system from satellite altimetry and model data

Author

Bruno Blanke, Nicolas Grima, Anna Rubio, Sabrina Speich, Claude Roy, Laboratoire de physique des océans (LPO), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Ground truth, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 010505 oceanography, Continental shelf, Mesoscale meteorology, Front (oceanography), Geology, Pelagic zone, Aquatic Science, 01 natural sciences, Oceanography, Eddy, 13. Climate action, Climatology, Upwelling, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Sea level, 0105 earth and related environmental sciences
Abstract

International audience; We characterize eddy activity in the southern Benguela upwelling system with absolute sea level data deduced from remote-sensing measurements and numerical simulations run with a regional model, using a wavelet-based technique for identification and tracking of coherent structures. Statistics on eddy count, size, type and location are obtained along the continental slope of the upwelling system for a common period of interest shared by model and satellite data. We draw a comparison between mesoscale variability calculated by the regional model and ground truth accounted by satellite altimetry. We show that the presence of cyclonic eddies along the upwelling front over the South Benguela slope is recurrent throughout the year. Moreover, the agreement between model and observations is fair and validates the modeling approach. Tracking in the model of volume properties of continental slope, cyclonic eddies on their way toward the open ocean suggests that these eddies play a significant role in coastal–open ocean exchanges. With lifetimes of several months, these eddies can export significant volumes of nutrient-rich waters far from the coastal upwelling.

Published
2009

5. How fast can the European eel (Anguilla anguilla) larvae cross the Atlantic Ocean?

Author

Anne-Marie Tréguier, Youen Vermard, Nicolas Grima, Bruno Blanke, Sylvain Bonhommeau, Etienne Rivot, Olivier Le Pape, Eric Greiner, Laboratoire d'Ecologie Halieutique - Agrocampus Ouest, Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Mercator Océan, and Société Civile CNRS Ifremer IRD Météo-France SHOM

Subjects
0106 biological sciences, animal structures, Shortest distance, Gulf Stream, 010504 meteorology & atmospheric sciences, Range (biology), Aquatic Science, Oceanography, Lagrangian modelling, 01 natural sciences, Leptocephali, migration duration, Rheotaxis, medicine, Sargasso sea, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Otolith, geography, Larva, geography.geographical_feature_category, Continental shelf, 010604 marine biology & hydrobiology, fungi, Anguilla, Fishery, Fractals, medicine.anatomical_structure, Migration duration, fractals, Environmental science, leptocephali, human activities, Sargasso Sea
Abstract

International audience; The migration duration of European eel (Anguilla anguilla) larvae (leptocephali) from the spawning areas in the Sargasso Sea to the European continental shelf remains highly controversial, with estimates varying from 6 months to more than 2 yr. We estimated the fastest migration period and the shortest distance travelled by eel larvae by simulating Lagrangian particles released in the Sargasso Sea and by simulating a range of larval behaviours (fixed-depth drift, vertical diurnal migration and active-depth selection to maximize current velocity). This enabled us to compute (i) a passive drift speed, and (ii) a hypothetic swimming speed needed for European eel larvae to cross the Atlantic in 6 months (i.e., the migration duration estimated from otolith daily growth increments). Our results show that the minimum travel time for an eel larva that is passively drifting was 10 months and 3 days. Active behaviours (vertical diurnal migration and rheotaxis) paradoxically increased the migration period. We found that for leptocephali to cross the Atlantic Ocean in 6 months, they would need to swim a minimum of 3.4 body lengths per second for 8200 km. No larvae have been observed with such swimming capabilities. These results provide evidence that leptocephali cannot cross the Atlantic in 6 months.

Published
2009

6. Quantifying tracer dynamics in moving fluids: a combined Eulerian-Lagrangian approach

Author

Peter Franks, Bruno Blanke, Fanny Chenillat, Pascal Rivière, Xavier Capet, Nicolas Grima, Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Processus de couplage à Petite Echelle, Ecosystèmes et Prédateurs Supérieurs (PEPS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), CNES (Centre National d'Btudes Spatiales), as part of the Ifesta-Up project funded by the TOSCA (Terre, Océan, Surfaces Continentales, Atmosphère) program, Scripps Institution of Oceanography (SIO), University of California-University of California, Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], coherent structures, Mesoscale meteorology, mesoscaleprocesses, 01 natural sciences, Lagrangiantrajectories, biophysical interactions, Eulerian lagrangian, Physics::Fluid Dynamics, symbols.namesake, eddy tracking, biophysicalinteractions, TRACER, Lagrangian coherent structures, coherentstructures, 14. Life underwater, Statistical physics, lcsh:Environmental sciences, 0105 earth and related environmental sciences, General Environmental Science, Hydrology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:GE1-350, 010505 oceanography, Lagrangian trajectories, Dynamics (mechanics), ecosystemfunctioning, Eulerian path, Ocean dynamics, Eddy, plankton dynamics, 13. Climate action, eddytracking, ecosystem functioning, Environmental Science, ocean dynamics, mesoscale processes, symbols, planktondynamics, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; Eulerian models coupling physics and biology provide a powerful tool for the study of marine systems, complementing and synthesizing in situ observations and in vitro experiments. With the monotonic improvements in computing resources, models can now resolve increasingly complex biophysical interactions. Quantifying complex mechanisms of interaction produces massive amounts of numerical data that often require specialized tools for analysis. Here we present an Eulerian-Lagrangian approach to analyzing tracer dynamics in moving fluids. As an example of its utility, we apply this tool to quantifying plankton dynamics in oceanic mesoscale coherent structures. In contrast to Eulerian frameworks, Lagrangian approaches are particularly useful for revealing physical pathways, and the dynamics and distributions of tracers along these trajectories. Using a well-referenced Lagrangian tool, we develop a method to assess the variability of biogeochemical properties (computed using an Eulerian model) along particle trajectories. We discuss the limitations of this new method, given the different biogeochemical and physical timescales at work in the Eulerian framework. We also use Lagrangian trajectories to track coherent structures such as eddies, and we analyze the dynamics of the local ecosystem using two techniques: (i) estimating biogeochemical properties along trajectories, and (ii) averaging biogeochemical properties over dynamic regions (e.g., the eddy core) defined by ensembles of similar trajectories. This hybrid approach, combining Eulerian and Lagrangian model analyses, enhances the quantification and understanding of the complex planktonic ecosystem responses to environmental forcings; it can be easily applied to the dynamics of any tracer in a moving fluid.

Published
2015
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7. Environmental characteristics of Agulhas rings affect interocean plankton transport

Author

Colomban de Vargas, Stefanie Kandels-Lewis, Gregory K. Farrant, Laurence Garczarek, Hiroyuki Ogata, Silvia G. Acinas, Pascal Hingamp, Shruti Malviya, Lucie Bittner, Bruno Blanke, Matthew B. Sullivan, Michael J. Follows, Sarah Searson, Patrick Wincker, Oliver Jahn, Emilie Villar, Cyrille Lepoivre, Jennifer R. Brum, Shinichi Sunagawa, Thomas Vannier, Lionel Guidi, Pierre Testor, Tara Oceans Coordinators, Hervé Le Goff, Chris Hill, Daniele Iudicone, Stéphane Audic, Sébastien Santini, Stephane Pesant, Adriana Zingone, Gabriel Gorsky, Fabrice Not, Nicolas Grima, Jean-Baptiste Romagnan, Céline Dimier, Atsuko Tanaka, Raffaella Casotti, Jean-Pierre Gattuso, Flora Vincent, John R. Dolan, Eric Pelletier, Alison Chase, Jean-Louis Jamet, Emmanuel Boss, Eleonora Scalco, Fabrizio D'Ortenzio, Peer Bork, Christophe Brunet, Marc Picheral, Sabrina Speich, Simon Roux, Chris Bowler, Eric Karsenti, Sarah M. Schwenck, Information génomique et structurale (IGS), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Adaptation et diversité en milieu marin (ADMM), Institut national des sciences de l'Univers (INSU - CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Massachusetts Institute of Technology (MIT), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut de biologie de l'ENS Paris (IBENS), Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), University of Arizona, Stazione Zoologica Anton Dohrn (SZN), University of Maine, Observatoire océanologique de Villefranche-sur-mer (OOVM), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Processus de Transfert et d'Echanges dans l'Environnement - EA 3819 (PROTEE), Université de Toulon (UTLN), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Développement Instrumental et Techniques Marines (DITM), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Genoscope - Centre national de séquençage [Evry] (GENOSCOPE), Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Génomique métabolique (UMR 8030), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS), Variabilité de l'Océan et de la Glace de mer (VOG), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), European Molecular Biology Laboratory [Heidelberg] (EMBL), Institute of Marine Sciences / Institut de Ciències del Mar [Barcelona] (ICM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Max Delbrück Centre for Molecular Medicine, Data Publisher for Earth and Environmental Science (PANGAEA), University of Bremen, We appreciate the commitment of the following people and sponsors: CNRS (in particular, Groupement de Recherche GDR3280), European Molecular Biology Laboratory (EMBL), Genoscope/CEA, VIB, Stazione Zoologica Anton Dohrn, UNIMIB, Fund for Scientific Research–Flanders, Rega Institute, KU Leuven, the French Ministry of Research, the French government Investissements d’Avenir programmes OCEANOMICS (ANR-11-BTBR-0008), FRANCE GENOMIQUE (ANR-10-INBS-09-08), MEMO LIFE (ANR-10-LABX-54), PSL* Research University (ANR-11-IDEX-0001-02), and ANR (projects POSEIDON/ ANR-09-BLAN- 0348, PHYTBACK/ANR-2010-1709-01, PROMETHEUS/ANR-09-PCS-GENM-217, SAMOSA/ANR-13-ADAP0010, and TARAGIRUS/ANR-09-PCS-GENM-218), European Union FP7 (MicroB3/No.287589, IHMS/HEALTH-F4-2010-261376, and MaCuMBA/No.311975), ERC Advanced Grant Award to C.B. (Diatomite: 294823), Gordon and Betty Moore Foundation grant (no. 3790) to M.B.S., Spanish Ministry of Science and Innovation grant CGL2011-26848/BOS MicroOcean PANGENOMICS to S.G.A., TANIT (CONES 2010-0036) from the Agència de Gestió d´Ajusts Universitaris i Reserca to S.G.A., JSPS KAKENHI grant no. 26430184 to H.O., NASA Ocean Biology and Biogeochemistry program (NNX11AQ14G and NNX09AU43G) to E.B., The Italian Research for the Sea (Flagship Project RITMARE) to D.I., and FWO, BIO5, and Biosphere 2 to M.B.S. We also appreciate the support and commitment of Agnès b. and Etienne Bourgois, the Veolia Environment Foundation, Region Bretagne, Lorient Agglomeration, World Courier, Illumina, the EDF Foundation, FRB, the Prince Albert II de Monaco Foundation, and the Tara schooner and its captains and crew. We thank MERCATOR-CORIOLIS and ACRI-ST for providing daily satellite data during the expedition. We are also grateful to the French Ministry of Foreign Affairs for supporting the expedition and to the countries that graciously granted sampling permissions. Tara Oceans would not exist without continuous support from 23 institutes (http://oceans.taraexpeditions.org). We also acknowledge excellent assistance from the European Bioinformatics Institute (EBI), in particular G. Cochrane and P. ten Hoopen, as well as the EMBL Advanced Light Microscopy Facility (ALMF), in particular R. Pepperkok. We thank Y. Timsit for stimulating scientific discussions and critical help during writing of the manuscript. The altimeter products were produced by Ssalto/Duacs and CLS, with support from CNES., ANR-11-BTBR-0008,OCEANOMICS,Biotechnologies et bioressources pour la valorisation des écosystèmes marins planctoniques(2011), ANR-10-INBS-0009,France-Génomique,Organisation et montée en puissance d'une Infrastructure Nationale de Génomique(2010), ANR-10-IDEX-0001,PSL,Paris Sciences et Lettres(2010), ANR-09-BLAN-0348,POSEIDON(2009), ANR-10-BLAN-1709,PHYTBACK,Rétroactions écologie-climat dues à l'évolution de la taille et de la forme du phytoplancton(2010), ANR-13-ADAP-0010,SAMOSA,Synechococcus as a model genus for studying adaptation of marine phytoplankton to environmental changes(2013), European Project: 287589,EC:FP7:KBBE,FP7-OCEAN-2011,MICRO B3(2012), European Project: 261376,EC:FP7:HEALTH,FP7-HEALTH-2010-single-stage,IHMS(2011), European Project: 294823,EC:FP7:ERC,ERC-2011-ADG_20110310,DIATOMITE(2012), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Institut de biologie de l'ENS Paris (UMR 8197/1024) (IBENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université d'Évry-Val-d'Essonne (UEVE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Département de Biologie - ENS Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0303 health sciences, Atlantic hurricane, Biogeochemical cycle, Multidisciplinary, 010504 meteorology & atmospheric sciences, Ocean current, fungi, Biology, Plankton, 01 natural sciences, 03 medical and health sciences, Indian ocean, Oceanography, Biological dispersal, Seawater, 14. Life underwater, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Nitrogen cycle, 030304 developmental biology, 0105 earth and related environmental sciences
Abstract

Villar, Emilie ... et. al.-- 11 pages, 8 figures, supplementary materials www.sciencemag.org/content/348/6237/1261447/suppl/DC1, Agulhas rings provide the principal route for ocean waters to circulate from the Indo-Pacific to the Atlantic basin. Their influence on global ocean circulation is well known, but their role in plankton transport is largely unexplored. We show that, although the coarse taxonomic structure of plankton communities is continuous across the Agulhas choke point, South Atlantic plankton diversity is altered compared with Indian Ocean source populations. Modeling and in situ sampling of a young Agulhas ring indicate that strong vertical mixing drives complex nitrogen cycling, shaping community metabolism and biogeochemical signatures as the ring and associated plankton transit westward. The peculiar local environment inside Agulhas rings may provide a selective mechanism contributing to the limited dispersal of Indian Ocean plankton populations into the Atlantic. © 2015, American Association for the Advancement of Science. All rights reserved, We appreciate the commitment of the following people and sponsors: CNRS (in particular, Groupement de Recherche GDR3280); European Molecular Biology Laboratory (EMBL); Genoscope/CEA; VIB; Stazione Zoologica Anton Dohrn; UNIMIB; Fund for Scientific Research–Flanders; Rega Institute, KU Leuven; the French Ministry of Research; the French government Investissements d’Avenir programmes OCEANOMICS (ANR-11-BTBR-0008), FRANCE GENOMIQUE (ANR-10-INBS-09-08), MEMO LIFE (ANR-10-LABX-54), PSL* Research University (ANR-11-IDEX-0001-02), and ANR (projects POSEIDON/ ANR-09-BLAN- 0348, PHYTBACK/ANR-2010-1709-01, PROMETHEUS/ANR-09-PCS-GENM-217, SAMOSA/ANR-13-ADAP-0010, and TARAGIRUS/ANR-09-PCS-GENM-218); European Union FP7 (MicroB3/No.287589, IHMS/HEALTH-F4-2010-261376, and MaCuMBA/No.311975); ERC Advanced Grant Award to C.B. (Diatomite: 294823); Gordon and Betty Moore Foundation grant (no. 3790) to M.B.S.; Spanish Ministry of Science and Innovation grant CGL2011-26848/BOS MicroOcean PANGENOMICS to S.G.A.; TANIT (CONES 2010-0036) from the Agència de Gestió d´Ajusts Universitaris i Reserca to S.G.A.; JSPS KAKENHI grant no. 26430184 to H.O.; NASA Ocean Biology and Biogeochemistry program (NNX11AQ14G and NNX09AU43G) to E.B.; The Italian Research for the Sea (Flagship Project RITMARE) to D.I.; and FWO, BIO5, and Biosphere 2 to M.B.S.We also appreciate the support and commitment of Agnès b. and Etienne Bourgois, the Veolia Environment Foundation, Region Bretagne, Lorient Agglomeration, World Courier, Illumina, the EDF Foundation, FRB, the Prince Albert II de Monaco Foundation, and the Tara schooner and its captains and crew. We thank MERCATOR-CORIOLIS and ACRI-ST for providing daily satellite data during the expedition. We are also grateful to the French Ministry of Foreign Affairs for supporting the expedition and to the countries that graciously granted sampling permissions. Tara Oceans would not exist without continuous support from 23 institutes (http://oceans.taraexpeditions.org)

Published
2015

8. Comparative study of potential transfer of natural and anthropogenic cadmium to plankton communities in the North-West African upwelling

Author

Eric Machu, Mathieu Waeles, Pierre-Amaël Auger, Thomas Gorgues, Nicolas Grima, Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR-11-CEPL-0005,ÉPURE,Éléments trace métalliques Perturbations climatiques Upwelling et REssources(2011), European Project: 264933,EC:FP7:ENV,FP7-ENV-2010,EURO-BASIN(2010), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Water mass, VARIATION SAISONNIERE, Environmental Engineering, Food Chain, 010504 meteorology & atmospheric sciences, UPWELLING, 010501 environmental sciences, North-West African upwelling, 01 natural sciences, Natural (archaeology), [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, ADVECTION MARINE, POLLUTION MARINE, PHOSPHATE, Environmental Chemistry, Animals, Marine ecosystem, Seawater, 14. Life underwater, Phosphate industry, Waste Management and Disposal, Ecosystem, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, ACCUMULATION, 0105 earth and related environmental sciences, Plankton ecosystem, Advection, ACL, Fishes, ZONE COTIERE, Plankton, Dispersion, MODELISATION, Pollution, Bioaccumulation, Oceanography, Productivity (ecology), Mollusca, MILIEU MARIN, METAL LOURD, Environmental science, Upwelling, POLLUTION CHIMIQUE, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, PLANCTON, Water Pollutants, Chemical, Cadmium
Abstract

International audience; A Lagrangian approach based on a physical–biogeochemical modeling was used to compare the potential transfer of cadmium (Cd) from natural and anthropogenic sources to plankton communities (Cd-uptake) in the North-West African upwelling. In this region, coastal upwelling was estimated to be the main natural source of Cd while the most significant anthropogenic source for marine ecosystem is provided by phosphate industry. In our model experiment, Cd-uptake (natural or anthropogenic) in the North-West African upwelling is the result of an interplay between the Cd dispersion (by advection processes) and the simulated biological productivity. In the Moroccan waters, advection processes limit the residence time of water masses resulting in a low natural Cd-uptake by plankton communities while anthropogenic Cd-uptake is high. As expected, the situation is reversed in the Senegalo-Mauritanian upwelling where natural Cd-uptake is higher than anthropogenic Cd-uptake. Based upon an estimate of Cd sources, our modeling study shows, unexpectedly, that the anthropogenic signal of potential Cd-bioaccumulation in the Moroccan upwelling is of the same order of magnitude as the natural signal mainly present in the Senegalo-Mauritanian upwelling region. A comparison with observed Cd levels in mollusk and fishes, which shows overall agreement with our simulations, is confirming our estimates.

Published
2015

9. The coupled physical-new production system in the equatorial Pacific during the 1992-1995 El Niño

Author

Thierry Moutin, Anne Stoens, Marie-Helene Radenac, Jean-Michel André, Nicolas Grima, Gérard Eldin, Patrick Raimbault, C. Navarette, Yves Dandonneau, Laurent Mémery, Christophe E. Menkès, and Dandonneau, Yves (ed.)

Subjects
FLUX, 0106 biological sciences, SALINITE, Atmospheric Science, Water mass, 010504 meteorology & atmospheric sciences, Soil Science, UPWELLING, Aquatic Science, Oceanography, 01 natural sciences, CYCLE BIOGEOCHIMIQUE, DYNAMIQUE DE L'EAU, OCEAN, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, EL NINO, TEMPERATURE, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Physics, BIOMASSE, Ecology, Advection, PRODUCTION BIOLOGIQUE, VARIABILITE, 010604 marine biology & hydrobiology, Ocean current, Paleontology, Forestry, Ocean general circulation model, New production, CHLOROPHYLLE, MODELISATION, Western Hemisphere Warm Pool, Geophysics, 13. Climate action, Space and Planetary Science, Nitrate transport, Upwelling, NITRATE
Abstract

We investigate the coupling between the physics and new production variability during the period April 1992 to June 1995 in the equatorial Pacific via two cruises and simulations. The simulations are provided by a high-resolution Ocean General Circulation Model forced with satellite-derived weekly winds and coupled to a nitrate transport model in which biology acts as a nitrate sink. The cruises took place in September-October 1994 and sampled the western Pacific warm pool and the upwelling region further east. The coupled model reproduces these contrasted regimes. In the oligotrophic warm pool the upper layer is fresh, and nitrate-depleted, and the new production is low. In contrast, the upwelling waters are colder, and saltier with higher nitrate concentrations, and the new production is higher. Along the equator the Eastern edge of the warm pool marked by a sharp salinity front, also coincides with a "new production front". Consistent with the persistent eastward surface currents during the second half of 1994, these fronts undergo huge eastward displacement at the time of the cruises. The warm/fresh poll and oligotrophic region has an average new production of 0.9 mmol NO3/m2/d, which is almost balanced by horizontal advection from the central Pacific and by vertical advection of richer water from the nitrate reservoir below. In contrast, the upwelling mesotrophic region shows average new production of 2.1 mmol NO3/m2/d and the strong vertical nitrate input by the equatorial upwelling is balanced by the losses, through westward advection and meridional divergence of nitrate rich waters, and by the biological sink. (Résumé d'auteur)

Published
1999

10. A Software Package and Hardware Tools for in situ Experiments in a Lagrangian Reference Frame

Author

Francesco Nencioli, Nicolas Grima, Gilles Rougier, Anne Petrenko, Andrea Doglioli, Jean-Luc Fuda, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Instrumentation, Moyens analytiques, Observatoires en Géophysique et Océanographie (IMAGO), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)

Subjects
0106 biological sciences, Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Lagrangian circulation, Mesoscale meteorology, Ocean Engineering, 01 natural sciences, symbols.namesake, Software, TRACER, Tracers, 14. Life underwater, Dispersion (water waves), Ship observations, 0105 earth and related environmental sciences, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Lagrangian circulation transport, Advection, business.industry, 010604 marine biology & hydrobiology, Dispersion, Software package, Experimental design, transport, symbols, business, Lagrangian, Marine engineering, Reference frame
Abstract

The Lagrangian Transport Experiment (LATEX) was developed to study the influence of coupled physical and biogeochemical dynamics at the meso- and submesoscales on the transfers of matter and heat between the coastal zone and the open ocean. One of the goals of the Latex10 field experiment, conducted during September 2010 in the Gulf of Lion (northwest Mediterranean), was to mark a dynamical mesoscale feature by releasing a passive tracer [sulfur hexafluoride (SF6)] together with an array of Lagrangian buoys. The goal was to release the tracer in an initial patch as homogeneous as possible in the horizontal, and to study its turbulent mixing and dispersion while minimizing the contribution due to advection. For that, it was necessary to continuously adjust the vessel route in order to remain as closely as possible in the Lagrangian reference frame moving with the investigated mesoscale structure. To accomplish this task, a methodology and software were developed, which are presented here. The software is equipped with a series of graphical and user-friendly accessories and the entire package for MATLAB can be freely downloaded (http://mio.pytheas.univ-amu.fr/~doglioli).

Published
2013

11. The exchange of Intermediate Water in the southeast Atlantic: Water mass transformations diagnosed from the Lagrangian analysis of a regional ocean model

Author

Sabrina Speich, Bruno Blanke, Julie Rimaud, and Nicolas Grima

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Soil Science, Aquatic Science, Structural basin, Oceanography, 01 natural sciences, 010305 fluids & plasmas, Geochemistry and Petrology, Cape, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, Antarctic Intermediate Water, geography.geographical_feature_category, Ecology, Paleontology, Forestry, Salinity, Current (stream), Geophysics, Eddy, Space and Planetary Science, Ridge, Climatology, Lagrangian analysis, Geology
Abstract

[1] Results from a regional ocean model and numerical Lagrangian analyses are compared with in situ measurements to describe the properties and dynamics of Antarctic Intermediate Water (AAIW) in the region of the Cape Basin. The AAIW that originates in the South Atlantic (A-AAIW) at 8°W follows two branches. A southern branch, flowing mostly south of 40°S, is blocked by topography and is deflected westward without significant changes in its physical properties. A northern branch crosses the Cape Basin with strong modification of its physical properties. The AAIW that originates in the Indian Ocean (I-AAIW) flows into the Atlantic Ocean via the Agulhas Current and undergoes small physical changes in the Cape Basin. In the model, the salinity ranges of A-AAIW and I-AAIW cores that reach the southeast Atlantic are 34.2–34.5 and 34.5–34.6, respectively. The modeled AAIW distribution and behavior compare well with observations, despite a bias of +0.2 in salinity. To investigate the dynamical processes involved in the interocean exchanges of these AAIW varieties, we use diagnoses based on the Okubo-Weiss parameter and the directional variations of trajectories of particles transported by the model velocity field. Our results suggest that I-AAIW flows into the Cape Basin more within eddies, and particularly within cyclones, than A-AAIW. Once the mixing of both varieties operates, physical and behavioral differences fade and the resulting AAIW flows over the Walvis Ridge in a less turbulent way as part of the Benguela Current, with salinity between 34.55 and 34.6.

Published
2012

12. Sensitivity of advective transfer times across the North Atlantic Ocean to the temporal and spatial resolution of model velocity data: Implication for European eel larval transport

Author

Sylvain Bonhommeau, Nicolas Grima, Bruno Blanke, Yann Drillet, Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), UMR 212 EME 'écosystèmes marins exploités' (EME), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM), Mercator Océan, and Société Civile CNRS Ifremer IRD Météo-France SHOM

Subjects
0106 biological sciences, Atmospheric Science, 010504 meteorology & atmospheric sciences, Ocean modeling, Oceanography, 01 natural sciences, Data assimilation, Ocean circulation, Transfer (computing), 14. Life underwater, Computers in Earth Sciences, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, geography, Larva, geography.geographical_feature_category, European eel migration time, Continental shelf, Advection, 010604 marine biology & hydrobiology, Lagrangian trajectories, Ocean current, Geology, Gulf Stream, Oceanic eddies, Eddy, Environmental science
Abstract

International audience; European eel (Anguilla anguilla) larvae achieve one of the longest larval migrations of the marine realm, i.e., more than 6000 km from their spawning grounds in the Sargasso Sea to European continental shelves. The duration of this migration remains debated, between 7 months and 3 years. This information is, however, crucial since it determines the period over which larvae are affected by environmental conditions and hence the subsequent recruitment success. We investigate the pathways and duration of trans-Atlantic connections using 3 years of high-resolution (daily, 1/12°) velocity fields available from a Mercator-Océan model configuration without data assimilation. We study specifically the effect of spatial and temporal resolutions on our estimates by applying various filters in time (from daily to 12-day averages) and space (from 1/12° to 1° gridcell aggregation) to the nominal model outputs. Numerical particles are released in the presumed European eel spawning area and considered as passive tracers at three specific depths (around 0, 50, and 200 m). We diagnose particularly the intensity of the water transfer between suitable control sections that encompass the eel larva distribution. Transit ages are also investigated, with a particular focus on the pathways that minimize the connection times between the western and eastern North Atlantic. We show that small-scale structures (eddies and filaments) contribute to faster connections though they also correspond to additional complexity in trajectories. The shortest pathways mostly follow the Gulf Stream and the North Atlantic Drift, whereas interior connections require longer transfers that prove less compatible with biological observations.

Published
2012

13. On the origins of water masses exported along both sides of Greenland: A Lagrangian model analysis

Author

Anne-Marie Tréguier, Nicolas Grima, Camille Lique, Bruno Blanke, Laboratoire de physique des océans (LPO), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, Water mass, 010504 meteorology & atmospheric sciences, Beaufort Gyre, Soil Science, Aquatic Science, Oceanography, 01 natural sciences, Geochemistry and Petrology, Circumpolar deep water, Earth and Planetary Sciences (miscellaneous), Sea ice, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, Arctic dipole anomaly, 010505 oceanography, North Atlantic Deep Water, Paleontology, Forestry, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Thermohaline circulation, Surface water, Geology
Abstract

International audience; The origin of the water masses exported from the Arctic to the North Atlantic along both sides of Greenland is investigated using an original numerical method. A quantitative Lagrangian analysis is applied to the monthly climatological 3‐D output of a global ocean/sea ice high‐resolution model. It allows quantification of the different branches of the export to the North Atlantic, as well as related timescales and water mass transformations. In the model, the outflow through Davis Strait consists in equal parts of Pacific and Atlantic water, whilst the export through Fram Strait consists almost fully of Atlantic water (contrary to observations). Pacific water is transferred quickly (O(10 years)) to the North Atlantic through the Beaufort Gyre, where gradual warming and salinification occur. Atlantic water exiting in the surface layer along both sides of Greenland remains about 10 years in the Arctic Basin and undergoes cooling and significant freshening. Below the surface water, Atlantic water exiting through the intermediate and deep layers in Fram Strait follows different pathways in the Arctic, with trajectories being subject to topography constraints. The travel time depends strongly on the pathway (from 1 to 1000 years). The intermediate outflow consists mainly of water entering the Arctic at Fram Strait, while half the deep outflow is composed of water from the Barents Sea. We find that the Barents Sea Branch, which contributes to both the outflows at Fram and Davis straits, is almost fully transformed after a year due to heat exchanges with the very cold atmosphere (in the Barents Sea).

Published
2010

14. Optimal surface salinity perturbations of the meridional overturning and heat transport in a global Ocean general circulation model

Author

Anthony T. Weaver, Jérôme Vialard, Nicolas Grima, Mahdi Ben Jelloul, Florian Sévellec, Thierry Huck, Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), CERFACS, Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL)

Subjects
TEMPERATURE DE SURFACE, SALINITE, DENSITE, 010504 meteorology & atmospheric sciences, 010505 oceanography, Ocean current, Perturbation (astronomy), Zonal and meridional, Mechanics, Ocean general circulation model, Oceanography, 01 natural sciences, MODELISATION, Salinity, CIRCULATION OCEANIQUE, Meridional flow, Climatology, ANOMALIE, Initial value problem, Thermohaline circulation, 14. Life underwater, TRANSFERT DE CHALEUR, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract

Recent observations and modeling studies have stressed the influence of surface salinity perturbations on the North Atlantic circulation over the past few decades. As a step toward the estimation of the sensitivity of the thermohaline circulation to salinity anomalies, optimal initial surface salinity perturbations are computed and described for a realistic mean state of a global ocean general circulation model [Océan Parallélisé (OPA)]; optimality is defined successively with respect to the meridional overturning circulation intensity and the meridional heat transport maximum. Although the system is asymptotically stable, the nonnormality of the dynamics is able to produce a transient growth through an initial stimulation. Optimal perturbations are calculated subject to three constraints: the perturbation applies to surface salinity; the perturbation conserves the global salt content; and the perturbation is normalized, to remove the degeneracy in the linear maximization problem. Maximization using Lagrangian multipliers leads to explicit solutions (rather than eigenvalue problems), involving the integration of the model adjoint for each value to maximize. The most efficient transient growth for the intensity of the meridional overturning circulation appears for a delay of 10.5 yr after the perturbation by the optimal surface salinity anomaly. This optimal growth is induced by an initial anomaly located north of 50°N. In the same way, the most efficient transient growth for the intensity of the meridional heat transport appears for a shorter delay of 2.2 yr after the perturbation by the optimal surface salinity anomaly. This initial optimal perturbation corresponds to a zonal salinity gradient around 24°N. The optimal surface salinity perturbations studied herein yield upper bounds on the intensity of the response in meridional overturning circulation and meridional heat transport. Using typical amplitudes of the Great Salinity Anomalies, the upper bounds for the associated variability are 0.8 Sv (1 Sv ≡ 106 m3 s−1) (11% of the mean circulation) and 0.03 PW (5% of the mean circulation), respectively.

Published
2008

15. An eddy permitting model of the Atlantic circulation : evaluating open boundary conditions

Author

Anne-Marie Tréguier, Nicolas Grima, Maurice Imbard, Sylvain Michel, Gurvan Madec, Bernard Barnier, J. M. Molines, A. de Miranda, Christophe Messager, Thierry Reynaud, Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Institut du développement et des ressources en informatique scientifique (IDRIS), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Wave propagation, Soil Science, Zonal and meridional, Aquatic Science, Oceanography, 01 natural sciences, 010305 fluids & plasmas, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Geochemistry and Petrology, 0103 physical sciences, Numerical modeling, Earth and Planetary Sciences (miscellaneous), Boundary value problem, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Mechanics of the fluids [physics.class-ph], Heat balance, Advection, General circulation, Paleontology, Forestry, Model resolution, Geophysics, Heat flux, 13. Climate action, Space and Planetary Science, Climatology, Geology
Abstract

As part of the French CLIPPER project, an eddy permitting model of the Atlantic circulation has been run for 22 years. The domain has open boundaries at Drake passage and at 30 degreesE, from Africa to Antarctica. The simulated mean circulation, as well as the eddy activity, is satisfactory for a 1/3 degrees model resolution, and the meridional heat transport at 30 degreesS is within the range estimated from observations. We use the "mixed" open boundary algorithm of Barnier et al. [1998], which has both a radiation condition and a relaxation to climatology. The climatological boundary forcing strongly constrains the solution in the whole domain. The model heat balance adjusts through the surface (heat flux retroaction term) more than the open boundaries. The radiation phase velocities calculated within the algorithm are analyzed. This shows, quite surprisingly, that both the eastern and western boundaries have a similar behavior, regardless of the preferred directions for advection (mainly eastward) and wave propagation (mainly westward). Our results confirm that open boundary algorithms behave differently according to the dynamics of the region considered. The passive boundary condition that Penduff et al. [2000] applied successfully in the north eastern Atlantic does not work in the present South Atlantic model. We emphasize the need for a careful prescription of the climatology at the open boundary, for which a new approach based on synoptic sections is implemented.

Published
2001

16. Prediction of sea level anomalies using ocean circulation model forced by scatterometer wind and validation using TOPEX/Poseidon data

Author

Abderrahim Bentamy, Pascale Delecluse, K. Katsaros, Nicolas Grima, and Yves Quilfen

Subjects
Global Drifter Program, 010504 meteorology & atmospheric sciences, Buoy, Meteorology, 010505 oceanography, ocean surface, Ocean current, Wind stress, Atmospheric model, ocean model, Scatterometer, sea level, 01 natural sciences, Ocean surface topography, 13. Climate action, Climatology, General Earth and Planetary Sciences, Environmental science, 14. Life underwater, Altimeter, scatterometer, Electrical and Electronic Engineering, 0105 earth and related environmental sciences
Abstract

Uncertainties in the surface wind field have long been recognized as a major limitation in the interpretation of results obtained by oceanic circulation models. It is especially true in the tropical oceans, where the response to wind forcing is very strong on short time scales. The purpose of this paper is to show that these uncertainties can be greatly reduced by using spaceborne wind sensors that provide accurate measurements on a global basis.Surface winds over the global oceans have been measured by scatterometry since the launch of the European Remote Sensing Satellite (ERS-1) in August 1991 by the European Space Agency, Noordwijk, The Netherlands, and is currently provided by ERS-2, launched in April 1995. The ground track wind vectors are processed to compute mean weekly surface winds onto a 1 degrees square grid at the Institut Francais de Recherche pour 1'Exploitation de la Mer (IFREMER), Plouzane, France. These winds are validated by comparison with the buoy array in the tropical Pacific ocean, showing good agreement. In order to further evaluate this wind field, the three dimensional (3-D) ocean model OPA7 developed at Laboratoire d'Oceanographie Dynamique et de Climatologie, Paris, Prance, is forced over the tropical oceans by the ERS-derived wind stress fields and by fields from the atmospheric model Arpege/Climat. Selected ocean parameters are defined in order to validate the ocean model results with measurements of the tropical ocean and global atmosphere (TOGA) buoys in the Pacific ocean. The ability of the model to describe the short scale (a few weeks to a few years) oceanic variability is greatly enhanced when the satellite-derived surface forcing is used.In this paper, we present further comparison of the ocean model results with the TOPEX-Poseidon altimeter measurements. Simulated and measured sea level variability are described over the three tropical oceans. The annual and semi-annual signals, as well as the interannual variability, partly linked to the El Nino southern oscillation (ENSO) phenomenon, are well simulated by the OPA7 model when the satellite winds are used. Furthermore, it shows that the objective method, kriging technique, used to interpolate the mean ERS wind fields, dramatically reduces the effects of the satellite bandlike sampling. In the last part of this paper, we focus on the relationship between the wind stress anomalies and the sea level anomalies in the case of the 1997-1998 El Nino event. It clearly shows that sea level anomalies in the eastern and western parts of the Pacific are strongly linked to wind stress anomalies in the central Pacific. The forthcoming scatterometers aboard the METOP and ADEOS satellites will provide a much better coverage. It will enable the wind variability spatial and temporal scares to be resolved better, in order that wind uncertainties no longer blur the interpretation of ocean circulation numerical models results.

Published
2000

17. Sensibility study of an Oceanic General Circulation Model forced by satellite wind-stress fields

Author

Pascale Delecluse, Yves Quilfen, Nicolas Grima, Abderrahim Bentamy, Claire Levy, Kristina B. Katsaros, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Soil Science, Wind stress, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Oceanography, 01 natural sciences, Current meter, Acoustic Doppler current profiler, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, Buoy, 010505 oceanography, Ocean current, Paleontology, Forestry, Ocean general circulation model, Scatterometer, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Thermocline, Geology
Abstract

Satellite wind and wind stress fields at the sea surface, derived from the scatterometers on European Remote Sensing satellites 1 and 2 (ERS-1 and ERS-2) are used to drive the ocean general circulation model (OGCM) “OPA” in the tropical oceans. The results of the impact of ERS winds are discussed in terms of the resulting thermocline, current structures, and sea level anomalies. Their adequacy is evaluated on the one hand by comparison with simulations forced by the Arpege-Climat model and on the other hand by comparison with measurements of the Tropical Atmosphere-Ocean (TAO) buoy network and of the TOPEX/Poseidon altimeter. Regarding annual mean values, the thermal and current responses of the OGCM forced by ERS winds are in good agreement with the TAO buoy observations, especially in the central and eastern Pacific Ocean. In these regions the South Equatorial Current, the Equatorial Undercurrent, and the thermocline features simulated by the OGCM forced by scatterometer wind fields are described. The impact of the ERS-1 winds is particularly significant to the description of the main oceanic variability. Compared to the TAO buoy observations, the high-frequency (a few weeks) and the low-frequency of the thermocline and zonal current variations are described. The correlation coefficients between the time series of the thermocline simulated by ERS winds and that observed by the TAO buoy network are highly significant; their mean value is 0.73, over the whole basin width, while it is 0.58 between Arpege model simulation and buoy observations. At the equator the time series of the zonal current simulated by the ERS winds, at three locations (110°W, 140°W, and 165°E) and at two depths, are compared to the TAO current meter and acoustic Doppler current profiler (ADCP) measurements. The mean value of the significant correlation coefficients computed with the in situ measurements is 0.72 for ERS, while it is 0.51 for the Arpege-Climat model. Thus ERS wind fields through the OGCM generate more realistic current variations than those obtained with Arpege climate winds, and they are particularly efficient in capturing abrupt changes (“wind bursts”) which may be important regarding ocean dynamics.

Published
1999

18. GLOBEC special issue

Author

John Hampton, Jean-Michel André, Anne Stoens, Nicolas Grima, Patrick Lehodey, Michel Bertignac, Christophe E. Menkès, and Laurent Mémery

Subjects
0106 biological sciences, Skipjack tuna, 010504 meteorology & atmospheric sciences, PRODUCTION PRIMAIRE, Fishing, Aquatic Science, Oceanography, Convergence zone, 01 natural sciences, POISSON MARIN, 14. Life underwater, DISTRIBUTION SPATIALE, Skipjack, 0105 earth and related environmental sciences, biology, Advection, 010604 marine biology & hydrobiology, biology.organism_classification, MODELISATION, Salinity, CIRCULATION OCEANIQUE, Upwelling, Tuna, Geology, RELATION PREDATEUR PROIE
Abstract

Skipjack tuna (#Katsuwonus pelamis$) contributes approximately to 70% of the total tuna catch in the Pacific Ocean. This species occurs in the upper mixed-layer throughout the equatorial region, but the largest catches are taken from the warmpool in the Western equatorial Pacific. Analysis of catch and effort data for US purse seine fisheries in the Western Pacific has demonstrated that one of the most successful fishing grounds is located in the vicinity of a convergence zone between the warm (greater than 28-29° C) low-salinity water of the warmpool and the cold saline water of equatorial upwelling in the central Pacific (Lehodey et al, 1997). This zone of convergence, identified by a well-marked salinity front and approximated by the 28.5° C isotherm, oscillates zonally over several thousands of km in correlation with the El Nino-Southern Oscillation. The present study focuses on the prediction of skipjack tuna forage that is expected to be a major factor in explaining the basin-scale distribution of the stock. It could also explain the close relation between displacements of skipjack tuna and the convergence zone on the eastern edge of the warmpool. A simple bio-geochemical model was coupled with a general circulation model, allowing reasonable predictions of new primary production in the equatorial Pacific from mid-1992 to mid-1995. The biological transfer of this production toward tuna forage was simply parameterized according to the food chain length and redistributed by the currents using the circulation model. Tuna forage accumulated in the convergence zone of the horizontal currents, which corresponds to the warmpool/equatorial upwelling boundary. Predicted forage maxima corresponded well with high catch rates. (Résumé d'auteur)

Published
1998

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