title: Statistical analysis of global wind dynamics in vigorous Rayleigh-Bénard convection.
abstract: Experimental and numerical studies of thermal convection have shown that sufficiently vigorous convective flows exhibit a large-scale thermal wind component sweeping along small-scale thermal boundary layer instabilities. A characteristic feature of these flows is an intermittent behavior in the form of irregular reversals in the orientation of the large-scale circulation. There have been several attempts toward a better understanding and description of the phenomenon of flow reversals, but so far most of these models are based on a statistical analysis of few-point measurements or on simplified theoretical assumptions. The analysis of long-term data sets (>5×10(5) turnover times τ(t)=d/u(rms)) obtained by numerical simulations of turbulent two-dimensional Rayleigh-Bénard convection allows us to get a more comprehensive view of the spatio-temporal flow behavior. By means of a global statistical analysis of the characteristic spatial modes of the flow we extract information about the stability of dominant large-scale modes as well as the reversal paths in state subspace. We examine probability density functions and drift vector fields of two-dimensional state subspaces spanned by different large-scale spatial modes. This also provides information about the coexistence of dominant modes.
authors.affiliation: Institut für Geophysik, Westfälische Wilhelms-Universität Münster, Germany. klaus.petschel@uni-muenster.de
authors.forename: K
authors.initials: K
authors.lastname: Petschel
authors.forename: M
authors.initials: M
authors.lastname: Wilczek
authors.forename: M
authors.initials: M
authors.lastname: Breuer
authors.forename: R
authors.initials: R
authors.lastname: Friedrich
authors.forename: U
authors.initials: U
authors.lastname: Hansen