Nonlinear Processes in Oceanic and Atmospheric Flows

Presentation

Environmental intermittency versus behavioral intermittency: evolutionary perspectives.

Author: Laurent Seuront, CNRS & Flinders U..

Names and affiliation of other authors:

Oral or poster: Oral presentation

Abstract:
The intermittent nature of the marine environment is considered from both physical and biological perspectives through investigations of the highly nonlinear properties of (i) turbulent velocity, temperature and salinity, and (ii) nutrient, phytoplankton and zooplankton concentrations as a function of turbulent kinetic energy dissipation rates. Turbulent velocity, temperature and salinity exhibit a universal signature independent of turbulence intensity. In contrast, biological scalars exhibit a far more complex structure which can be very distinct from the one of a passive scalar, and suggest that the biological activity of minute plankton organisms might significantly alter the effect of turbulent diffusion. The swimming behaviors of invertebrates and vertebrates are shown to exhibit very similar intermittent patterns that are reminiscent of the patterns observed in their surrounding fluid environments for scales ranging from millimeters to kilometers. The swimming behaviors of both invertebrate and vertebrate organisms considered here, the copepod Temora longicornis and the sunfish Mola mola, belong to the class of multifractal random walks (MRW), characterized by a nonlinear moment scaling function for distance versus time. This clearly differs from the traditional Brownian and fractional Brownian walks expected or previously detected in animal behaviors. The divergence between MRW and LÚvy flight and walk is also discussed.

*Satellite images from NASA and ESA

Nonlinear Processes in Oceanic and Atmospheric Flows. July 2-4, 2008. Castro Urdiales, Cantabria, Spain.