NG42A-01 INVITED

Predictability and Uncertainties in Geophysics: from the Butterfly Effect to Ensemble Predictions, Multifractal Predictability and the Anthropocene

* Schertzer, D J Daniel.Schertzer@enpc.fr, CNRM/GAME Meteo-France & CNRS, 42 Av. G. Coriolis, Toulouse, 31057 Cx, France
* Schertzer, D J Daniel.Schertzer@enpc.fr, Universite Paris-Est Ecole des Ponts ParisTech CEREVE, 6-8 Avenue Blaise Pascal Cité Descartes, Marne-la-Vallee, 77455 Cx2, France

This lecture pays a tribute to Ed Lorenz whose works on atmospheric predictability yielded a revolution in science and generated new interdisciplinary domains called chaos, nonlinear sciences and complex systems. This revolution demonstrated that geophysics are not only applied sciences, but face fundamental problems that can stimulate the entire scientific community and therefore beget new tools. A popular example is the paradigm of the butterfly effect that has already inspired concrete advances such as the ensemble prediction approaches that became operational in the last decade. But, Ed Lorenz also pointed out that the predictability of systems complex in both space and time, such as turbulence, might be quite different from that of systems that are complex only in time. This finally led to the notion of multifractal predictability that will be introduced in a pedagogical manner and shown to yield concrete tools to assess the evolution of the extremes in our changing climate.

NG42A-02

Transport in an idealized three-gyre system with application to the surface flow in the Adriatic Sea.

* Rypina, I I irypina@whoi.edu, Woods Hole Oceanographic Institution, Physical Oceanography Department, Woods Hole road, Clark bldg., Woods Hole, MA 0254, United States
Pratt, L J lpratt@whoi.edu, Woods Hole Oceanographic Institution, Physical Oceanography Department, Woods Hole road, Clark bldg., Woods Hole, MA 0254, United States
Brown, M G mbrown@rsmas.miami.edu, University of Miami, Rosenstiel School of Marine and Atmospheric Science, 4600 Rickenbacker Cswy., Miami, FL 33149, United States
Udovydchenkov, I A iudovydchenkov@whoi.edu, Woods Hole Oceanographic Institution, Department of Applied Ocean Physics and Engineering, Water Street, Bigelow bldg., Woods Hole, MA 02543, United States
Kocak, H hk@math.miami.edu, University of Miami, Departments of Computer Science and Mathematics, 1365 Memorial Drive, Coral Gables, FL 33146, United States

Theoretical results and numerical methods from dynamical systems theory are used to study mixing and transport in an idealized three-gyre system with application to the surface flow in the Adriatic Sea. Much of the work focuses on the role of transport barriers, their dynamics and methods of their identification. Particular attention is paid to the issue of intergyre transport. The velocity field is assumed to be two-dimensional and incompressible, and composed of a steady three-gyre background flow on which a time-dependent perturbation is superimposed. Two systems of this type are considered: 1) an analytical model of the Adriatic Sea; and 2) an observationally-based altimetry-derived model of the Adriatic Sea. It is shown that transport properties of the perturbed three-gyre system are qualitatively different for small and large perturbation. For a small perturbation to the steady three-gyre background flow two of the gyres exchange no fluid with the third gyre. When the perturbation strength exceeds a certain threshold transport between all three gyres occurs. This behavior is described theoretically, illustrated using the analytic model and shown to be consistent with the observationally-based model of the Adriatic Sea.

Authors (2008), Title, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract xxxxx-xx