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Charlas y Presentaciones

Stretching fields and lines from finite-size Lyapunov exponents: ocean transport and biological impact

By Hernandez-Garcia, Emilio
Invited talk at the workshop Exploring Complex Dynamics in High-Dimensional Chaotic Systems: From Weather Forecasting to Oceanic Flows , Dresden 25-29 January 2010 2010

The Lagrangian description of fluid motion has been largely enriched with the introduction of stretching quantifiers such as the different types of Lyapunov exponents. In this talk I will focus on the finite-size Lyapunov exponent case, as applied to horizontal ocean flows estimated from satellite altimetry. I will argue on the relationship of the structures revealed by the Lyapunov analysis with the material manifolds of dynamical systems theory. Then, the influence of these structures on biological organisms will be illustrated with examples from the bottom and from the top of marine ecosystems: The distribution of phytoplankton in ocean upwelling areas, and the trajectories of frigatebirds in the West Indian Ocean, which fly on top of the ridges of Lyapunov structures.