Hobart

Seminar Abstract

Friday 7 May 2010, 11.30am (Tas time)
CSIRO Auditorium, Hobart

Kurt Polzin
Physical Oceanographer
Woods Hole Oceanographic Institution
USA

Toward Regional Characterizations of the Oceanic Internal Wavefield

Many major oceanographic internal wave observational programs of the last 4 decades are reanalyzed in order to characterize variability of the deep ocean internal wavefield. The observations are discussed in the context of the universal spectral model proposed by Garrett and Munk. The Garrett and Munk model is a good description of wintertime conditions at Site-D on the continental rise north of the Gulf Stream. Elsewhere and at other times, significant deviations in terms of amplitude, separability of the 2-D vertical wavenumber - frequency spectrum, and departure from the model's functional form are noted.

Attempts are made to interpret the variability in terms of the interplay between generation, propagation and nonlinearity using a statistical radiative balance equation. Nonlinearity is a fundamental organizing principle in this work. The observed power laws lie close to the Induced Diffusion stationary states of the resonant kinetic equation describing the lowest order nonlinear transfers. Eddy variability and by implication wave-mean interactions are also an organizing principle. Observations from regions of low eddy variability tend to be outliers in terms of their parametric spectral representation. Other data tend to cluster in two regions of parameter space. It is, however, difficult to reconcile direct estimates of the temporal evolution of the resonant kinetic equation as indicating that GM76 represents a stationary state, either alone or in combination with wave-mean interactions. This process frames major questions for future research with the insight that such integrative studies could constrain both observationally and theoretically based interpretations.

Seminar recording

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Clothilde Langlais, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5399
Natalie Kelly, (Biology/Modelling seminars) CSIRO Marine and Atmospheric Research 0438 452 483
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 11/05/10