Michael E. McIntyre
In: Dynamics, Transport and Photochemistry in the Middle Atmosphere of the Southern Hemisphere, Proc. San Francisco NATO Workshop, ed. A. O'Neill; Dordrecht, Kluwer, pp. 1-18 (1990).
This invited conference paper, available here as a pdf scan (2.7Mbyte, © 1990 Kluwer), is centred around `the tendency for naturally-occurring turbulence to be spatially inhomogeneous', a conspicuous tendency that's incompatible with the standard assumptions of classical turbulence theory. Examples include not only ocean-beach breakers and `what can be seen out of aeroplane windows', but also the tendency of large-scale, layerwise-two-dimensional turbulence to self-limit by forming what are now called `eddy-transport barriers' -- back in 1990 I called them `PV barriers' -- of the kind so well illustrated by the sub-polar and subtropical eddy-transport barriers in the wintertime stratosphere.
I now think that `eddy-transport barriers' is the best term,
emphasizing first that they are barriers to layerwise-two-dimensional
eddy transport but not to mean transport (by diabatic or
residual mean circulations), and second that isentropic
gradients of potential vorticity (PV) are not the only factor.
As Martin Juckes and I pointed out in 1987,
the peculiar resilience of these barriers,
even down to small scales and even for aperiodic disturbances,
is related
not only to PV gradients and the consequent
Rossby-wave quasi-elasticity
but also to shear. For a recent review see
my 2008 paper with David Drischel in the
Journal of the Atmospheric Sciences,
65, 855-874,
Multiple jets as PV
staircases:
the Phillips effect and the
resilience of eddy-transport
barriers
(.pdf, 1.5 Mbyte, © 2008 American Meteorological Society)
and
for a key theoretical development beyond that review a
paper by Richard Wood and myself,
A general theorem on
angular-momentum changes due to
potential
vorticity mixing and on
potential-energy changes due to
buoyancy
mixing,
now out in J. Atmos. Sci 67, 1261-1274.
Its corollaries include a new nonlinear
stability theorem for shear flows.
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