Ocean Science www.ocean-sci.net 1812-0784 1812-0792 3 3 2007 10.5194/os-3-441-2007 http://www.ocean-sci.net/3/441/2007/ http://www.ocean-sci.net/3/441/2007/os-3-441-2007.html http://www.ocean-sci.net/3/441/2007/os-3-441-2007.pdf 441 449 2007-10-01 Internal tides and energy fluxes over Great Meteor Seamount T. Gerkema gerk@nioz.nl H. van Haren Royal NIOZ, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands Internal-tide energy fluxes are determined halfway over the southern slope of Great Meteor Seamount (Canary Basin), using data from combined CTD/LADCP yoyoing, covering the whole water column. The strongest signal is semi-diurnal and is concentrated in the upper few hundred meters of the water column. An indeterminacy in energy flux profiles is discussed; it is argued that a commonly applied condition used to determine these profiles is in fact invalid over sloping bottoms. However, the vertically integrated flux can be established unambiguously; the observed results are compared with the outcome of a numerical internal-tide generation model. For the semi-diurnal internal tide, the vertically integrated flux found in the model corresponds well to the observed one. The observed diurnal signal appears to be largely of non-tidal origin. Dietrich, G.: Ozeanographie – physische Geographie des Weltmeeres, Georg Westermann Verlag, Braunschweig, 1970. Egbert, G D. and Ray, R D.: Semi-diurnal and diurnal tidal dissipation from TOPEX/Poseidon altimetry, Geophys. Res. Lett., 30, 1907, doi:10.1029/2003GL017676, 2003. Feistel, R. and Hagen, E.: On the GIBBS thermodynamic potential of seawater, Progr. Oceanogr., 36, 249–327, 1995. Garcia Lafuente, J., Sarhan, T., Vargas, M., Vargas J M., and Plaza, F.: Tidal motions and tidally-induced fluxes through La Linea submarine canyon, western Alboran Sea, J. Geophys. Res., 94, 18 185–18 194, 1999. Gerkema, T., Lam, F P A., and Maas, L R M.: Internal tides in the Bay of Biscay: conversion rates and seasonal effects, Deep-Sea Res. II, 51, 2995–3008, 2004. Gerkema, T. and Shrira, V I.: Near-inertial waves on the "non-traditional" β plane, J. Geophys. Res., 110, C01003, doi:10.1029/2004JC002519, 2005. Gerkema, T., Staquet, C., and Bouruet-Aubertot, P.: Decay of semi-diurnal internal-tide beams due to subharmonic resonance, Geophys. Res. Lett., 33, L08604, doi:10.1029/2005GL025105, 2006. Hibiya, T., Nagasawa, M., and Niwa, Y.: Nonlinear energy transfer within the oceanic internal wave spectrum at mid and high latitudes, J. Geophys. Res., 107(C11), 3207, doi:10.1029/2001JC001210, 2002. Klymak, J. M., Moum, J N., Nash, J D., Kunze, E., Girton, J B., Carter, G S., Lee, C M., Sanford, T B., and Gregg, M C.: An estimate of tidal energy lost to turbulence at the Hawaiian Ridge, J. Phys. Oceanogr., 36, 1148–1164, 2006. Kunze, E., Rosenfeld, L K., Carter, G S., and Gregg, M C.: Internal waves in Monterey Submarine Canyon, J. Phys. Oceanogr., 32, 1890–1913, 2002. MacKinnon, J A. and Winters, K B.: Subtropical catastrophe: Significant loss of low-mode tidal energy at 28.9° N, Geophys. Res. Lett., 32, L15605, doi:10.1029/2005GL023376, 2005. Mohn, C. and Beckmann, A.: The upper ocean circulation at Great Meteor Seamount. Part I: Structure of density and flow fields, Ocean Dynamics, 52, 179–193, doi:10.1007/s10236-002-0017-4, 2002. Nash, J D., Alford, M H., and Kunze, E.: Estimating internal wave energy fluxes in the ocean, J. Atmos. Oceanic Techn., 22, 1551–1570, 2005. Nash, J D., Kunze, E., Lee, C M., and Sanford, T B.: Structure of the baroclinic tide generated at Kaena Ridge, Hawaii, J. Phys. Oceanogr., 36, 1123–1135, 2006. Rainville, L. and Pinkel, R.: Baroclinic energy flux at the Hawaiian Ridge: observations from the R/P \em FLIP, J. Phys. Oceanogr., 36, 1104–1122, 2006. Smith, W H F. and Sandwell, D T.: Global sea floor topography from satellite altimetry and ship depth soundings, Science, 277, 1956–1962, 1997. van Haren, H.: Details of stratification in a sloping bottom boundary layer of Great Meteor Seamount, Geophys. Res. Lett., 32, L07606, doi:10.1029/2004GL022298, 2005a. van Haren, H.: Tidal and near-inertial peak variations around the diurnal critical latitude, Geophys. Res. Lett., 32, L23611, doi:10.1029/2005GL024160, 2005b. van Haren, H.: Cruise report bsik/LOCO-IW06: R.V. Pelagia cruise 64PE248, 17 May–12 June 2006, NIOZ, 2006. Zaron, E D. and Egbert, G D.: Estimating open-ocean barotropic tidal dissipation: the Hawaiian Ridge, J. Phys. Oceanogr., 36, 1019–1035, 2006.