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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Modelling the interactions of near-inertial waves
and vortical motion in the ocean - Vanneste\, J (U
niversity of Edinburgh)
DTSTART;TZID=Europe/London:20131203T144500
DTEND;TZID=Europe/London:20131203T153000
UID:TALK49146AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/49146
DESCRIPTION:Co-author: Eric Danioux (University of Edinburgh)
\n\nWind forcing of the ocean generates a spectrum
of inertia-gravity waves that is sharply peaked n
ear the local inertial (or Coriolis) frequency. Th
e corresponding near-inertial waves (NIWs) make a
dominant contribution to the vertical velocity and
vertical shear in the ocean\; they therefore play
an important role for mixing\, biological product
ivity\, pollutant dispersion and\, arguably\, the
thermohaline circulation. An asymptotic model prop
osed by Young and Ben Jelloul describes the slow e
volution of NIWs that results from weak dispersion
and from their interactions with the quasi-two-di
mensional vortical motion. We derive this YBJ mode
l by applying a form of Whitham averaging to the v
ariational formulation of the primitive equations
for a rotating stratified fluid. This provides a d
irect route to the YBJ equation and elucidates its
variational structure and conservation laws. We t
hen consider the effect of turbulent vortical moti
on (modelled as a homogeneous random field) of a s
cale similar to that of the waves. Specifically\,
we derive a transport equation for NIWs that descr
ibes their scattering by the vortical motion and s
how how this scattering leads to an isotropization
of the NIW field. Direct numerical simulations of
the YBJ equations are used to test the prediction
s of the transport equation. Possible models of th
e two-way coupling between NIWs and vortical motio
n are also discussed.\n
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:Mustapha Amrani
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