University of Calgary
Monday, January 28, 2008
Center Green Laboratory 1, Room 2126
Event Decomposition of Intermittent Spatiotemporal Patterns in Nature and Simulations
Critical avalanches of instabilities in sandpile models and bursty localized energy dissipation in high-Reynolds number fluids are paradigmatic examples of multiscale intermittency in nonlinear systems with spatially extended degrees of freedom.
In this talk, I will present a novel approach for dealing with these and other manifestations of complex intermittent behavior which is abundant in nature and simulations. The approach is based on spatiotemporal decomposition of a continuous time-dependent turbulent field (either numerical or observational) into a collection of discrete dissipation events composed of contiguous spatial regions of propagating activity. The developed method provides a detailed representation of the intermittent component of the studied dynamics including its most essential physical and topological parameters, while significantly reducing the amount of stored information. It also allows to selectively address different classes of intermittent disturbances based on a flexible set of filtering criteria. The efficiency of the proposed approach will be illustrated by several space physics applications (bursty dissipation in the solar corona, particle precipitation in the auroral zone, localized magnetic reconnection in a driven plasma sheet), and its relevance to ongoing NCAR projects will be discussed.