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ISC-PIF Guest Researcher  //




Francesco d'Ovidio



My main interest is dynamical system theory and nonlinear dynamics in applications, especially where quantitative modeling is possible. I have worked on the emergence of collective properties in populations of natural and artificial units (respectively, yeast cells and electronic circuits). Currently I am focused on the problem of transport and mixing in geophysical flows and on the interaction between turbulence and biogeochemical tracers (like phytoplankton) in the ocean.

 

Institute of Complex Systems ISC-PIF
57-59 Rue Lhomond, 75005 Paris (France)
and
LOCEAN - IPSL, Université Pierre et Marie Curie
4 place Jussieu, 75252 Paris Cedex 5 (France)
francesco.dovidio AT iscpif.fr



Personal page : www.iscpif.fr/~dovidio

Research


Nonlinear ocean dynamics


The ocean is characterized by the interaction of spatial and temporal scales that span several orders of magnitude. Due to the presence of strong nonlinearities (e.g., from turbulence and biochemical processes), the response of an ocean component is hardly proportional to the perturbation and can easily propagate to other spatiotemporal scales. For this reason, the impact of the scales unresolved in models or observations is a constant and unavoidable source of uncertainties for our knowledge of the climate system and its predictability.

Currently, I am focused on the role of filaments in the ocean. Satellite and in situ observations of the ocean show the ubiquitous presence of filaments of biogeochemical tracers like phytoplankton, salinity and heat. These filaments have a large aspect ratio, having a width of a few km and a length of several hundreds of km. Filaments present a serious problem to our understanding of the ocean: because of their width and relatively short lifetimes (weeks) they are difficult to observe in details and are completely unresolved by global oceanic circulation models (including the Earth Simulator). However, we know that they are hot spots for biochemical and physical activity: for instance, filaments are the regions where marine predators (from penguins to human beings) concentrate their activity. Filaments are also associated to mixing and to vertical transport that exposes the interior of the ocean to the surface layer, allowing photosynthesis and atmospheric exchange.
In my work I try to understand filaments by combining observations and model studies. In particular I focus on the dynamical mechanisms that generate filaments and the way they interact with the ocean physics and ecology. Recently, I have contributed to field study like the LOHAFEX fertilization experiment.


Synchronization and emergence of collective properties: Dynamical quorum sensing


The phenomenon of synchronization is widespread in both natural and artificial systems, whenever some oscillating units are coupled together. Nonlinear dynamics provide a theoretical framework to deduce general properties of populations of coupled elements that can oscillate. These properties may then be used to understand the emergence of collective behaviours. I focused on the case in which some oscillating units are collecting by a global coupling that depends on the mean state of the population. This condition greatly simplifies the mathematical analysis and can describe natural situations like the coupling of a population of cells in a strongly turbulent medium. I applied the theoretical findings to two experimental systems: the oscillating meatabolism of a population of yeast cells in a stirred reactor and the dynamics of chaotic electronic circuits that share a common signal. In the case of the metabolism of yeast cells, we were able to show that the synchronization of the metabolic oscillations can code in its amplitude and frequency a key ingredient of many properties of multicellular organism: the information about the size of the colony. In this way we could unveil a dynamical quorum sensing mechanism as opposed to the traditional quorum sensing that is coded on a static property (the concentration of a chemical species).



Collaborations

F. Ginelli, ISC-PIF.
M. Lévy, Laboratoire d'Océanographie et du Climat: Expérimentations et approches numériques (LOCEAN-IPSL), Paris, France.
R. Morrow, Laboratoire d'Etudes en Geophysique et Oceanographie Spatiale, Toulouse, France.
S. De Monte, Ecole Normale Supérieure, Paris, France.
S. Alvain, Laboratoire d'Océanologie et de Géosciences, Wimereux, France.
E. Shuckburgh, British Antarctic Survey, Cambridge, UK.
Y. Lehahn, Univ. of Tel-Aviv, Israel.
V. Smetacek, D. Wolf-Gladrow (AWI Germany)



Publications

  • F. d'Ovidio, C.A. Andersen, C.N. Ernstsen and E. Mosekilde, Bifurcation analysis of spiral growth processes in plants, Math. Comp. Sim., 1614, 1-16 (1999).
  • F. d'Ovidio and E. Mosekilde, Dynamical system approach to phyllotaxis, Phys. Rev. E, 61, 354-365 (2000).
  • S. Danø, F. Hynne, S. De Monte, F. d'Ovidio, H. Westerhoff, P. G. Sørensen, Synchronization of glycolitic oscillations in intact yeast cells, Faraday Discuss., 120, 261-276, (2001).
  • S. De Monte and F. d'Ovidio, Dynamics of order parameters for globally coupled oscillators, Europhys. Lett., 58, 21-27 (2002).
  • M. Maródi, F. d'Ovidio, T. Vicsek, Synchronization of oscillators with long range interaction: phase transition and anomalous finite size effects, Phys. Rev. E., 66, 011109 (2002) cond-mat/0201337.
  • S. De Monte, F. d'Ovidio, E. Mosekilde, Coherent regime of globally coupled dynamical systems, Phys. Rev. Lett., 90, 054102 (2003) cond-mat/0207701.
  • F. d'Ovidio, H. Bohr, P.-A. Lindgård, Solitons on H-bonds in proteins,J. of Physics: Condensed Matter, 15 S1699-S1707 (2003), cond-mat/0211626.
  • J. Aguirre, F. d'Ovidio, and M. Sanjuan, Yorke's game of survival, Phys. Rev. E 69, 016204 (2004).
  • S. De Monte, F. d'Ovidio, E. Mosekilde, H. Chaté, ''Noise induced macroscopic bifurcations in globally coupled chaotic units”, Phys. Rev. Lett., 92, 254101 (2004).
  • F. d'Ovidio, C. López, E. Hernández-García, V. Fernández, “Mixing structures in the Mediterranean sea from Finite-Size Lyapunov Exponents”, Geophys. Res. Lett., 31, L17203 (2004).
  • F. d'Ovidio, H.G. Bohr, P.-A. Lindgaard “Analytical tools for solitons and periodic waves corresponding to phonons on Lennard-Jones lattices in helical proteins”, Phys. Rev. E., 71, 026606 (2005).
  • S. De Monte, F. d'Ovidio, H. Chate', E. Mosekilde, ”Effects of microscopic disorder on the collective dynamics of globally coupled maps”, Physica D, 205, 25-40 (2005).
  • S. De Monte, F. d'Ovidio, E. Mosekilde, H. Chate', ”Low-dimensional chaos in populations of strongly-coupled noisy maps", Progress of Theoretical Physics, S161, 27-42 (2005).
  • I. Gomes Da Silva, S. De Monte, F. d'Ovidio, R. Toral, and C. Mirasso, “Coherent regimes of mutually coupled Chua circuits”, Phys. Rev. E., 73, 036203 (2006).
  • Y. Lehahn, F. d'Ovidio, M. Levy, E. Heifetz, “Stirring of the Northeast Atlantic spring bloom: a Lagrangian analysis based on multi-satellite data”, J. Geophys. Res., 112, C08005 (2007).
  • S. De Monte*, F. d'Ovidio*, S. Dano, P. G. Sorensen, “Dynamical quorum sensing”, Proc. Natl. Acad. of Sciences, 104, 18377 (2007).
  • F. d'Ovidio, E. Shuckburgh, B. Legras "Local diagnostic of mixing and barrier modulation at the tropopause. Part I: Lyapunov diffusivity", J. Atm. Sciences, 66 3678-3694 (2009).
  • E. Shuckburgh, F. d'Ovidio, B. Legras "Local diagnostic of mixing and barrier modulation at the tropopause. Part II: seasonal and interannual variability", J. Atm. Sciences, 66 3695-3706 (2009).
  • F. d'Ovidio, J. Isern-Fontanet, C. López, E. García-Ladona, E. Hernández-García, “Comparison between Eulerian diagnostics and the finite-size Lyapunov exponent computed from altimetry in the Algerian Basin”, Deep Sea Res. I, 56, 15-31 (2009).
  • F. d’Ovidio, V. Taillandier, I. Taupier-Letage and L. Mortier, “Lagrangian Validation of the Mediterranean Mean Dynamic Topography by extraction of Tracer Frontal Structures”, Mercator Ocean Quarterly Newsletter, 32: 24 (2009).
  • L. Resplendy, M. Lévy, F. d'Ovidio, L. Merlivat, “Evidence for intense submesoscale variability of pCO2 in the northeast Atlantic Ocean”, Global biogeochem. Cycles, 23, GB1017 (2009).

Submitted:
  • F. d'Ovidio, S. De Monte, S. Alvain, Y. Danonneau, and M. Lévy, “Ephemeral niches of phytoplankton types”, subm.
  • A. Despres, G. Riverdin, F. d'Ovidio, “Surface fronts and currents in the Irminger sea”, subm. To J. Physical Oceanography.
  • C. Cotté, F. d'Ovidio, A. Chaigneau, M. Lévy, I. Taupier-Letage, C. Guinet, “Scale-dependent interactions of resident Mediterranean whales with marine dynamics” subm. To Limnology and Oceanography.
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Page last modified on Monday 11 January, 2010 10:06:58 by Francesco d'Ovidio.