Abstract
Using a two-dimensional primitive equation model, we examine nonlinear responses of a semidiurnal tidal flow impinging on a seamount with a background Garrett-Munk-like (GM-like) internal wavefield. It is found that horizontally elongated pancake-like structures of high vertical wavenumber near-inertial current shear are created both in the near-field (the region over the slope of the seamount) and far-field (the region over the flat bottom of the ocean). An important distinction is that the high vertical wavenumber near-inertial current shear is amplified only at mid-latitudes in the far-field (owing to a parametric subharmonic instability (PSI)), whereas it is amplified both at mid-and high-latitudes (above the latitude where PSI can occur) in the near-field. In order to clarify the generating mechanism for the strong shear in the near-field, additional numerical experiments are carried out with the GM-like background internal waves removed. The experiments show that the strong shear is also created, indicating that it is not caused by the interaction between the background GM-like internal waves and the semidiurnal internal tides. One possible explanation is proposed for the amplification of high vertical wavenumber near-inertial current shear in the near-field where tide residual flow resulting from tide-topography interaction plays an important role in transferring energy from high-mode internal tides to near-inertial internal waves.
Similar content being viewed by others
References
Bryan, F. (1987): Parameter sensitivity of primitive equation ocean general circulation models. J. Phys. Oceanogr., 17(7), 970–985.
Egbert, G. D. and R. D. Ray (2000): Significant dissipation of tidal energy in the deep ocean inferred from satellite altimeter data. Nature, 405(6788), 775–778.
Furuichi, N., T. Hibiya and Y. Niwa (2005): Bispectral analysis of energy transfer within the two-dimensional oceanic internal wave field. J. Phys. Oceanogr., 35(11), 2104–2109, doi:10.1175/JPO2816.1.
Garrett, C. J. R. and W. H. Munk (1972): Space-time scales of internal waves. Geophys. Fluid Dyn., 3, 225–264.
Gill, A. E. (1982): Atmosphere-Ocean Dynamics. Academic Press, San Diego, Calif., 662 pp.
Gregg, M. C. (1989): Scaling turbulent dissipation in the thermocline. J. Geophys. Res., 94(C7), 9686–9698.
Hibiya, T. and M. Nagasawa (2004): Latitudinal dependence of diapycnal diffusivity in the thermocline estimated using a finescale parameterization. Geophys. Res. Lett., 31(1), L01301, doi:10.1029/2003GL017998.
Hibiya, T., Y. Niwa, K. Nakajima and N. Suginohara (1996): Direct numerical simulation of the roll-off range of internal wave shear spectra in the ocean. J. Geophys. Res., 101(C6), 14123–14129.
Hibiya, T., Y. Niwa and K. Fujiwara (1998): Numerical experiments of nonlinear energy transfer within the oceanic internal wave spectrum. J. Geophys. Res., 103(C9), 18715–18722.
Hibiya, T., M. Nagasawa and Y. Niwa (2002): Nonlinear energy transfer within the oceanic internal wave spectrum at mid and high latitudes. J. Geophys. Res., 107(C11), 3207, doi:10.1029/2001JC001210.
Hibiya, T., M. Nagasawa and Y. Niwa (2006): Global mapping of diapycnal diffusivity in the deep ocean based on the results of expendable current profiler (XCP) surveys. Geophys. Res. Lett., 33(3), L03611, doi: 10.1029/ 2005GL025218.
LeBlond, P. H. and L. A. Mysak (1978): Waves in the Ocean. Elsevier Scientific Publishing Company, Amsterdam, 602 pp.
Merrifield, M. A. and P. E. Holloway (2002): Model estimates of M2 internal tide energetics at the Hawaiian Ridge. J. Geophys. Res., 107(C8), 3179, doi:10.1029/2001JC000996.
Munk, W. H. (1966): Abyssal recipes. Deep-Sea Res., 13, 707–730.
Munk, W. H. (1981): Internal waves and small-scale processes. p. 264–291. In Evolution of Physical Oceanography, ed. by B. S. Warren and C. Wunsch, MIT Press, Cambridge, Mass.
Nagasawa, M., T. Hibiya, Y. Niwa, M. Watanabe, Y. Isoda, S. Takagi and Y. Kamei (2002): Distribution of fine-scale shear in the deep waters of the North Pacific obtained using expendable current profilers. J. Geophys. Res., 107(C12), 3221, doi:10.1029/2002JC001376.
Ou, H. W. and L. Maas (1986): Tidal-induced buoyancy flux and mean transverse circulation. Cont. Shelf Res., 5(6), 611–628.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Iwamae, N., Hibiya, T. & Niwa, Y. Numerical study of enhanced energy dissipation near a seamount. J Oceanogr 62, 851–858 (2006). https://doi.org/10.1007/s10872-006-0103-1
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10872-006-0103-1