Spice, internal waves, and sound speed in the upper ocean

Abstract The density and current structure at the Hawaiian Ridge was observed using SeaSoar and Doppler sonar during a survey extending from Oahu to Brooks Banks. Across- and along-ridge changes in internal wave statistics in the upper ocean within 200 km of the ridge are investigated. Internal waves with trough-to-crest amplitude as large as 60 m and horizontal wavelength of about 50 km are observed repeatedly in across-ridge sections of potential density. Within 150 km of the ridge, kinetic and potential energy density exceed open-ocean values with maxima about 10 times Garrett–Munk levels. In the Kauai Channel (KC), the kinetic energy density is largest along an M2 internal tide ray. The ray originates at the northern edge of the ridge peak at a large across-ridge change in topographic slope and terminates at the ocean surface about 30–40 km south of the ridge peak. Kinetic and potential energy density are larger on the south side of the ridge at KC, the side with larger topographic slope. Energy density is also larger on the south side of the ridge at KC in numerical model results and on the side of steeper topographic slope in analytical model results. Along the ridge, the largest observed values of mean-square shear and mean-square slope of isopycnal depth are collocated with the largest energy density in numerical model results. Mean-square shear and mean-square slope increase with decreasing bottom depth and with increasing M2 barotropic tidal forcing.

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A Numerical Technique for the Calculation of Dispersion Relations and Mode Functions for Upper Ocean Internal Waves.

10.21236/ada094240 ◽

1980 ◽

Author(s):

Irvin W. Kay ◽

Patricia J. Draper ◽

Wasyl Wasylkiwskyj

Keyword(s):

Internal Waves ◽

Numerical Technique ◽

Dispersion Relations ◽

Upper Ocean

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Effects of Sound Speed Fluctuations Due to Internal Waves in Shallow Water on Horizontal Wavenumber Estimation

Impact of Littoral Environmental Variability of Acoustic Predictions and Sonar Performance ◽

10.1007/978-94-010-0626-2_48 ◽

2002 ◽

pp. 385-392 ◽

Cited By ~ 1

Author(s):

Kyle M. Becker ◽

George V. Frisk

Keyword(s):

Shallow Water ◽

Internal Waves ◽

Sound Speed ◽

Speed Fluctuations

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Partitioning of energy, vorticity, and strain in upper-ocean internal waves

10.1063/1.33189 ◽

1981 ◽

Author(s):

D. Michael Milder

Keyword(s):

Internal Waves ◽

Upper Ocean

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Internal waves in JASIN

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1983.0011 ◽

1983 ◽

Vol 308 (1503) ◽

pp. 389-405 ◽

Cited By ~ 19

Keyword(s):

Internal Waves ◽

Internal Tide ◽

Deep Ocean ◽

Upper Ocean ◽

Velocity Measurements ◽

High Frequencies ◽

Topographic Features ◽

Rockall Trough ◽

Moored Current Meters ◽

The Continuum

The internal wavefield during the Joint Air—Sea Interaction (JASIN) experiment was monitored by moored current meters and moored and towed thermistor chains. The observations were concentrated in the upper ocean near the centre of Rockall Trough, but velocity measurements were also made near topographic features and throughout the water column. Observed spectra are compared with results from the deep ocean, as represented by the Garrett-Munk (GM) model of the spectral continuum, and are generally found to have spectral levels equal to or greater than the GM spectrum. The greatest deviation from the GM spectrum occurs at high frequencies and wavenumbers where the observed spectra often exhibit a spectral shoulder and high vertical coherence. These features, also found in other upper-ocean spectra, are explained by a model composed of three vertically standing modes. The spatial variation of internal wave variance is related to topography: variance is highest near rough topography. The ratio of variance in the semidiurnal tidal band to variance in a band in the continuum is approximately constant. The possibility of a dynamical link between the two frequency bands requires further investigation. The semidiurnal internal tide varies temporally and spatially. Rockall Bank is identified as the source of an energetic beam of tidal oscillations during a one-week period.

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