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Spectral slopes and peaks: moored observations of internal waves in the ocean Hans van Haren

Spectral slopes and peaks: moored observations of internal waves in the ocean Hans van Haren. Internal Wave Band –GM--continuum. Garrett and Munk ( 1972 ) model internal waves: Simplified density model Smooth, horizontal, reflecting sea floor

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Spectral slopes and peaks: moored observations of internal waves in the ocean Hans van Haren

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  1. Spectral slopes and peaks: moored observations of internal waves in the oceanHans van Haren NIOZ is part of the Netherlands Organisation for Scientific Research (NWO)

  2. Internal Wave Band –GM--continuum • Garrett and Munk (1972) model internal waves: • Simplified density model • Smooth, horizontal, reflecting sea floor • No tides, nonlinear effects, current shear, horizontal Coriolis,etc. • Kinematics: N-scaling spectrum? • Internal wave ‘continuum’: • Depends on smoothing: no deep gaps? Above noise floor? • Internal ‘inertio-gravity’ wave frequency () band: • f <  < N f vert. Cor. Par.; N buoy. freq. • min < f, N < maxincl. fhhor. Cor. Par. • 0 <  < 2 for N = 0

  3. higher harmonics dominate -1 slope: intermittency? Bay of Biscay ~45N Yearlong data : Ek- and polarization spectra Special band f-S2 (Levine 2002)=2: a change in baseline slope CR: 1 = circular; 0 =rectilinear Gonella (1972)

  4. change in baseline slope: caused by ‘background’, ‘buoyancy subrange’? Algerian Basin ~38N

  5. Inertial shear due to short scales? Ek S IWB-boundaries: inertial shear (e.g. PinkelJPO2008) Canary Basin: ~30N sub-inertial shear

  6. Inertial shear dominance ~30N PSI/SR but additional process? Latitude dependence inertial shear (Hibiya et al. 2002) North-Atlantic Ocean:

  7. Sub-f down; Super-f up Smearing due to small-scale N-steps? Sub-and super-f distribution Irminger Sea: ~59N down up Non-traditional IGW-bounds min < f; max > N N ~ f

  8. Small-scale stratification layers z = O(1 m) N/f U(f) U(D2)

  9. Change in inertial polarization/N Gyroscopic gravity waves? Nonzero w(f) Discrete stratification? S vs N   g fh f 2  1 1<2 Newly formed water mass 2006 Large-scale stratification layers z = O(100 m) Algerian Basin: ~38N 1997 Slantwise stability

  10. Coupling of w(N) and S(f)? Directly observed w-spectra: the importance of N (Pinkel 1981) Great Meteor Seamnt: 30N S w wADCP eADCP N-distribution z=1m Plankton motions: diurnal + hh

  11. Relation w(N) and steps: filling continuum? 130 m coherent wT Yearlong open ocean w-spectra: the importance of N Madeira Basin: ~32N w=-T/t/(dT/dz) N-distribution

  12. Layer dynamics: Internal waves in the Canary Basin (50 days out of 530) (Louis Gostiaux/Martin Laan) Questions?

  13. Coherence: IGW 0-phase diff. 2N: 180-phase diff  shear driven? Open ocean coherence: importance of 2N Madeira Basin: ~32N z(m)

  14. -1 slope Temperature spectra Yearlong open ocean NIOZ3 T-spectra: Madeira Basin: ~32N

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