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Frank Henyey

Senior Principal Physicist





Research Interests

Ocean Acoustics, Small Scale Physical Oceanography

Department Affiliation



B.A. Physics, University of California, Berkeley, 1963

Ph.D. Physics, California Institute of Technology, 1967


2000-present and while at APL-UW

Large-amplitude internal solitary waves observed in the northern South China Sea: Properties and energetics

Lien, R.-C., F. Henyey, B. Ma, and Y.J. Yang, "Large-amplitude internal solitary waves observed in the northern South China Sea: Properties and energetics," J. Phys. Oceanogr., 44, 1095-1115, doi:10.1175/JPO-D-13-088.1, 2014.

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1 Apr 2014

Five large-amplitude internal solitary waves (ISWs) propagating westward on the upper continental slope in the northern South China Sea were observed in May–June 2011 with nearly full-depth measurements of velocity, temperature, salinity, and density. As they shoaled, at least three waves reached the convective breaking limit: along-wave current velocity exceeded the wave propagation speed C. Vertical overturns of ~100 m were observed within the wave cores; estimated turbulent kinetic energy was up to 1.5 x 10-4 W kg-1. In the cores and at the pycnocline, the gradient Richardson number was mostly <0.25. The maximum ISW vertical displacement was 173 m, 38% of the water depth. The normalized maximum vertical displacement was ~0.4 for three convective breaking ISWs, in agreement with laboratory results for shoaling ISWs. Observed ISWs had greater available potential energy (APE) than kinetic energy (KE). For one of the largest observed ISWs, the total wave energy per unit meter along the wave crest E was 553 MJ m-1, more than three orders of magnitude greater than that observed on the Oregon Shelf. Pressure work contributed 77% and advection contributed 23% of the energy flux. The energy flux nearly equaled CE. The Dubriel–Jacotin–Long model with and without a background shear predicts neither the observed APE > KE nor the subsurface maximum of the along-wave velocity for shoaling ISWs, but does simulate the total energy and the wave shape. Including the background shear in the model results in the formation of a surface trapped core.

A Method to Determine Small-Scale Internal Wave and Spice Fields from a Single CTD Profile with Application to Three Long-Range Ocean Acoustics Experiments

Henyey, F.S., J.A. Mercer, R.K. Andrew, and A.W. White, "A Method to Determine Small-Scale Internal Wave and Spice Fields from a Single CTD Profile with Application to Three Long-Range Ocean Acoustics Experiments," Technical Memorandum, APL-UW TM 1-14, Applied Physics Laboratory, University of Washington, Seattle, 59 pp.

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20 Mar 2014

The smaller vertical scales of sound speed variability of several recent deep water Pacific
Ocean acoustic experiments are extracted from individual conductivity, temperature, depth
(CTD) casts taken along the acoustic paths of these experiments, close to the times of
the experiments. The sound speed variability is split into internal wave variability and
spice variability, as these two parts obey very different dynamics %u2013 the internal waves move
through the water and the spice field moves with the water. Larger scales are mostly
responsible for acoustic travel time fluctuations, but smaller scales are mostly responsible
for other important phenomena such as intensity and arrival angle fluctuations. A method
is presented to determine when the two components are separable. The internal wave
properties are consistent with a spectral model such as a generalized Garrett%u2013Munk model,
whereas the spice is very intermittent, and the measurements are not extensive enough
to confidently make a spice model for acoustic propagation purposes. Both the internal
wave results and the spice results are summarized as vertical wavenumber spectra over a
selected vertical depth interval, but with the spice, it must be understood that a spectral
model would be very different from the data, and that the three-dimensional horizontal%u2013
vertical spectrum would be pure conjecture. The spectral level of the (small-scale) spice,
averaged over all the profiles, is comparable to that of the internal waves, suggesting that it
is not significantly less important to acoustic propagation than are the (small-scale) internal

Reverberation clutter induced by nonlinear internal waves in shallow water

Henyey, F.S., and D. Tang, "Reverberation clutter induced by nonlinear internal waves in shallow water," J. Acoust. Soc. Am., 134, EL289, doi:10.1121/1.4818937, 2013.

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1 Oct 2013

Clutter is related to false alarms for active sonar. It is demonstrated that, in shallow water, target-like clutter in reverberation signals can be caused by nonlinear internal waves. A nonlinear internal wave is modeled using measured stratification on the New Jersey shelf. Reverberation in the presence of the internal wave is modeled numerically. Calculations show that acoustic energy propagating near a sound speed minimum is deflected as a high intensity, higher angle beam into the bottom, where it is backscattered along the reciprocal path. The interaction of sound with the internal wave is isolated in space, hence resulting in a target-like clutter, which is found to be greater than 10 dB above the mean reverberation level.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center