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SUMMARY:Propagation of the internal tide from a continental shelf: laborat
 ory and numerical experiments - Staquet\, C (Joseph Fourier Grenoble )
DTSTART:20081212T113000Z
DTEND:20081212T120000Z
UID:TALK15613@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Internal gravity waves in the deep ocean have been given much 
 importance for the last ten years\, since oceanographers realized the impo
 rtant role of fluid mixing in raising the cold abyssal water masses. Mixin
 g in the deep ocean\, below 2 or 3 kms\, is indeed thought to be mostly du
 e to nonlinear internal gravity waves. In the abyss\, internal waves resul
 t mainly from the interaction of the surface tide with the variable bottom
  topography and are referred to as the internal tide.\n\nThe thermal equil
 ibrium of the deep ocean thus depends upon local and strongly intermittent
  processes -the breaking internal tide- which occur on temporal scales of 
 the order of one minute and on spatial scales of the order of ten meters. 
 This gigantic difference in spatial and temporal scales requires the param
 eterization of the mixing processes in large scale circulation models. A d
 irect study of the breaking internal tide is therefore needed.\n\nThe pres
 ent study focuses upon the academic situation of a uniformly stratified oc
 ean\, when the surface tide interacts with an idealized two-dimensional co
 ntinental shelf. Numerical experiments have been conducted in close corres
 pondance with the laboratory experiments\, the geometrical and physical pa
 rameters being the same. The laboratory experiments have been performed on
  the rotating Coriolis platform in Grenoble. The nonlinear non-hydrostatic
  finite-volume numerical code developed at MIT was used to closely model t
 he experiments.\n\nIn this simplified situation\, the internal wave field 
 organizes as a rectilinear wave beam with tidal frequency. We shall discus
 s the generation mechanism and structure of the wave beam\, relying on the
 oretical modelling of internal wave emission by an oscillating body source
 . We shall also investigate the nonlinear dynamics of the tide\, when harm
 onics and parametric sub-harmonics are generated. The localization and qua
 ntification of mixing induced by the internal tide will eventually be cons
 idered.
LOCATION:Seminar Room 1\, Newton Institute
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