HR: 14:40h
AN: A13C-05    [Abstracts]
TI: Stratification-Turbulence Feedbacks Limit Nonlinear Interactions Between Large-Scale Eddies in the Atmosphere
AU: * Schneider, T
EM: tapio@gps.caltech.edu
AF: California Institute of Technology, MC 100-23 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Walker, C C
EM: chrisw@gps.caltech.edu
AF: California Institute of Technology, MC 100-23 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: It is generally held that atmospheric macroturbulence can be strongly nonlinear. Yet weakly nonlinear models successfully account for the length scales ($\sim$4000~km), time scales ($\sim$2~days), and for aspects of the structure of the energy-containing baroclinic eddies in the extratropics of the Earth atmosphere. Here we present theoretical arguments and simulations that suggest that the historic successes of weakly nonlinear models of atmospheric macroturbulence are not a coincidence but a result of self-organization of atmospheric macroturbulence into critical states of weak nonlinearity. A negative feedback between the extra\-tro\-pi\-cal thermal stratification and atmospheric macroturbulence limits nonlinear eddy--eddy interactions and the concomitant inverse cascade of eddy energy from the length scales of baroclinic instability to larger scales. The theory and simulations point to fundamental constraints on the climate of Earth and other planets.
DE: 3379 Turbulence
DE: 3319 General circulation
DE: 1620 Climate dynamics (3309)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting