Statistics of an Unstable Barotropic Jet from a Cumulant Expansion
arXiv:0705.0011 · doi:10.1175/2007JAS2510.1
Abstract
Low-order equal-time statistics of a barotropic flow on a rotating sphere are investigated. The flow is driven by linear relaxation toward an unstable zonal jet. For relatively short relaxation times, the flow is dominated by critical-layer waves. For sufficiently long relaxation times, the flow is turbulent. Statistics obtained from a second-order cumulant expansion are compared to those accumulated in direct numerical simulations, revealing the strengths and limitations of the expansion for different relaxation times.
23 pages, 8 figures. Version to appear in J. Atmos. Sci