[GTP] Fwd: Re: GTP Seminar May 6, 2013

[Carolyn Mueller]

Just a reminder of Monday's seminar.


On 4/30/2013 9:00 AM, Carolyn Mueller wrote:
> GTP Seminar
>
> AN OCEANIC ULTRA-VIOLET CATASTROPHE, WAVE-PARTICLE DUALITY AND A
> STRONGLY NONLINEAR CONCEPT OF GEOPHYSICAL TURBULENCE
> Kurt Polzin
>  Woods Hole Oceanographic Institution
>
> Monday, May 6, 2013
> Mesa Lab Main Seminar Room
> Lecture at 3:30pm
>
> Nonlinear interactions between high frequency internal waves
> interacting with larger vertical and horizontal scale waves having
> inertial frequency are investigated using ray tracing techniques,
> analytic approximations to kinetic equations, solutions for the
> moments of a diffusive approximation to the resonant kinetic equation
> and Taylor's identity for relative dispersion.  Tracing high frequency
> waves in one and two inertial wave backgrounds demonstrates that the
> infinitesimal amplitude and finite amplitude limits are
> phenomenologically distinct: the finite amplitude state is
> characterized by the coalescing of the two small scale members of the
> triad and a transition to a bound wave phenomena.  This coalescence
> marks the transition from the coupled oscillator paradigm to a
> particle (wave packet) in a potential well paradigm. Tracing high
> frequency waves in stochastic inertial wave backgrounds does not
> reveal any such transition.  Rather, the ray tracing results are
> phenomenologically consistent with the particle in a (stochastic) well
> paradigm, independent of amplitude.
>
> Tracing high frequency waves in a stochastic background of inertial
> oscillations also provides estimates of the temporal evolution for the
> ensemble mean and variance of vertical wavenumber of a test wave
> distribution.  These estimates are compared to the evolution of the
> first and second moments of a diffusive approximation to the resonant
> kinetic equation.  The diffusive closure manages to describe the
> evolution of the first two moments at energy levels an order of
> magnitude smaller than background oceanic values and predicts {\em no}
> transport of action to smaller scales.  At realistic energy levels the
> growth of the second moment is inhibited relative to the first,
> implying a finite downscale action transport.  We demonstrate using
> Taylor's identity for relative dispersion that the transition occurs
> when the interaction timescale becomes smaller than the decorrelation
> time scale of the interaction process.  We argue that the action
> transport in this parameter regime is the averaged product of particle
> size (action density) and velocity (time rate of change of the first
> moment).  This concept is the genesis for the heuristically motivated
> Finescale Parameterization which summarizes current knowledge relating
> turbulent dissipation to finescale internal wave spectra.
>
>
>

-- 
Carolyn Mueller
NCAR IMAGe
1850 Table Mesa Drive
Boulder, CO 80305
http://www2.image.ucar.edu/
Tel: 303 497-2491
Fax: 303-497-2483