[GTP] GTP Seminar at NCAR - Daniel Schertzer

[Silvia Gentile]

GTP Seminar

GEOPHYSICAL TURBULENCE, QUASI-GEOSTROPHISM AND FRACTIONAL VORTICITY 
EQUATIONS
Daniel Schertzer
U. Paris-est, Ecole des Ponts ParisTech, LEESU

The strong anisotropy of geophysical turbulence remains a challenging 
question. A recent debate on the aircraft data significance led to a 
thorough discussion of the limitations of the quasi-geostrophic 
approximation and turbulence, which in turn yielded deterministic-like 
fractional vorticity equations.
These equations were obtained with the help of an anisotropic scaling 
analysis, instead of the classical scale analysis to derive the 
quasi-geostrophic approximation. The former breaks the rotational 
symmetry of the 3D vorticity equations, but preserves scaling and yields 
a 2+Hz-dimensional turbulence (0≤Hz≤1). The corresponding precise 
definition of fractional dimensional turbulence already demonstrates 
that the classical 2-D and 3-D turbulence are not the main options to 
understand atmospheric and oceanic dynamics. Although 2+Hz-dimensional 
turbulence (with (0<Hz<1)) has more common features with 3-D turbulence 
than with 2-D turbulence, it has nevertheless very distinctive features: 
its scaling anisotropy is in agreement with the layered pancake 
structure, which is typical of rotating and stratified turbulence, but 
not of the classical 3-D turbulence.
We will point out possible implications for stochastic climate 
parametrisations and simulations, as well the relevance of the 
theoretical value Hz=5/9.


Friday, June 8, 2012
Foothills Laboratory 2, 1022 Large Auditorium
Lecture at 3:30pm

-- 
Silvia Gentile
NCAR IMAGe
1850 Table Mesa Drive
Boulder, CO 80305
303 497 2480
www2.image.ucar.edu