Turbulence in Two and Three Dimensions
Abstract
Laboratory experiments on a zonal flow in a rotating annulus yielded insight into the phenomenon of blocking in the atmosphere (where the jet stream is deflected poleward by blocking anticyclones that persist for 10 days or longer). With two symmetric ridges on the bottom of the laboratory annulus, the resulting flows were nearly zonal at high forcing, blocked at low forcing, and intermittently switched between zonal and blocked flows at intermediate forcing. These observations provide new criteria by which topographic effects on low-frequency atmospheric flows can be distinguished from thermal effects. A model of one-dimensional random walks was examined in which the probability distribution functions for forward and backward steps were both power laws but with different exponents. Relations were derived between the exponent for the variance of the displacement and the exponents for the probability distribution functions for forward and backward steps and for sticking events. The results for this model agree with observations of tracer particles in a multi-vortex flow in a laboratory rotating annulus. Another study developed a genetic algorithm that produces neural feedback controllers for chaotic systems. The computer program to implement the algorithm is available on the World Wide Web at http://chaos.ph.utexas.edu/^weeks/dsane/
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 17, 1998
- Accession Number
- ADA349591
Entities
People
- Harry L. Swinney
Organizations
- University of Texas at Austin