Between 1983 and 1989, acoustic pulse-like signals at 133-Hz, 60-ms resolution, were transmitted from Oahu to Northern California. Analysis of the data indicates that the early arriving, steep paths are stable over basin scales, whereas the late, near-axial paths are sensitive to ocean structure. The late paths undergo vertical scattering on the order of the acoustic waveguide, i.e., 1 km [J. Acoust. Soc. Am. 99, 173–184 (1996)]. The parabolic approximation is used to simulate pulse propagation over the vertical plane connecting the source and receiver. Several prescriptions are used for the speed of sound: (1) Climatologically averaged sound speed with and without a realization of internal waves superposed; (2) Measured mesoscale structure with and without a realization of internal waves superposed. The spectrum of the internal waves is given by Garrett and Munk. Modeled internal waves and the measured mesoscale structure are sufficient to explain the vertical scattering of sound by 1 km. The mesoscale structure contributes a travel time bias of 0.6 s for the late multipath. This bias is seen to be a relevant contribution in accounting for the travel times of the last arrival.

1.
J. L.
Spiesberger
and
F. D.
Tappert
, “
Kaneohe acoustic thermometer further validated with rays over 3700 km and the demise of the idea of axially trapped energy
,”
J. Acoust. Soc. Am.
99
,
173
184
(
1996
).
2.
J. L.
Spiesberger
,
K.
Metzger
, and
J. A.
Furgerson
, “
Listening for climatic temperature change in the northeast pacific: 1983–1989
,”
J. Acoust. Soc. Am.
92
,
384
396
(
1992
).
3.
J. A.
Colosi
and
S. M.
Flatté
, “
Mode coupling by internal waves for multimegameter acoustic propagation in the ocean
,”
J. Acoust. Soc. Am.
100
,
3607
3620
(
1996
).
4.
J. A. Colosi, “Random media effects in basin-scale acoustic transmissions,” in Monte Carlo Simulations in Oceanography, pp. 157–166. A’ha Huliko’a Hawaiian Winter Workshop, University of Hawaii at Manoa, 1997.
5.
J. A.
Colosi
,
S. M.
Flatté
, and
C.
Bracher
, “
Internal-wave effects on 1000-km oceanic acoustic pulse propagation: Simulation and comparison with experiment
,”
J. Acoust. Soc. Am.
96
,
452
468
(
1994
).
6.
T.
Vincenty
, “
Direct and inverse solutions of geodesics on the ellipsoid with application of nested equations
,”
Surv. Rev.
176
,
88
94
(
1975
).
7.
J. L.
Spiesberger
,
H. E.
Hurlburt
,
M.
Johnson
,
M.
Keller
,
S.
Meyers
, and
J. J.
O’Brien
, “
Acoustic thermometry data compared with two ocean models: The importance of Rossby waves and ENSO in modifying the ocean interior
,”
Dyn. Atmos. Oceans
26
,
209
240
(
1998
).
8.
S. Levitus, “Climatological atlas of the world ocean,” in NOAA Prof. Pap. 13. U.S. Government Printing Office, Washington, DC, 1982.
9.
V. A.
Del Grosso
, “
New equation for the speed of sound in natural waters with comparisons to other equations
,”
J. Acoust. Soc. Am.
56
,
1084
1091
(
1974
).
10.
J. B. Bowlin, J. L. Spiesberger, T. F. Duda, and L. F. Freitag, “Ocean acoustical ray-tracing software ray,” Technical report, Woods Hole Oceanographic Institution, 1992.
11.
National Geophysical Data Center, Boulder, CO, “5 minute gridded world elevations and bathymetry—a digital database,” 1987.
12.
C.
Garrett
and
W.
Munk
, “
Space-time scales of internal waves
,”
Geophys. Fluid Dyn.
2
,
225
264
(
1972
).
13.
C.
Garrett
and
W.
Munk
, “
Space-time scales of internal waves: a progress report
,”
J. Geophys. Res.
80
,
291
297
(
1975
).
14.
L. B.
Dozier
and
F. D.
Tappert
, “
Statistics of normal mode amplitudes in a random ocean
,”
J. Acoust. Soc. Am.
63
,
353
365
(
1978
).
15.
S. Flatté, R. Dashen, W. Munk, K. Watson, and F. Zachariasen, Sound Transmission Through a Fluctuating Ocean (Cambridge University Press, Cambridge, 1979).
16.
M.
Leontovich
and
V.
Fock
, “
Solution of the problem of propagation of electromagnetic waves along the earth’s surface by the parabolic equation method
,”
Zh. Eksp. Teor. Fiz.
16
,
557
573
(
1946
).
17.
Frederick D. Tappert, The Parabolic Approximation Method, edited by J. B. Keller and J. S. Papadakis (Springer-Verlag, New York, 1977), pp. 224–287.
18.
F. D. Tappert, K. B. Smith, and M. A. Wolfson, “Analysis of the split-step Fourier algorithm for the solution of parabolic wave equations,” Math. Modeling Sci. Comp. (in press).
19.
F. D.
Tappert
and
M. G.
Brown
, “
Asymptotic phase errors in parabolic approximations to the one-way Helmholtz equation
,”
J. Acoust. Soc. Am.
99
,
1405
1413
(
1996
).
20.
F. D.
Tappert
,
J. L.
Spiesberger
, and
Linda
Boden
, “
New full-wave approximation for ocean acoustic travel time predictions
,”
J. Acoust. Soc. Am.
97
,
2771
2782
(
1995
).
21.
J.
Bowlin
, “
Generating eigenray tubes from two solutions of the wave equation
,”
J. Acoust. Soc. Am.
89
,
2663
2669
(
1997
).
22.
J. L.
Spiesberger
, “
Ocean acoustic tomography: Travel time biases
,”
J. Acoust. Soc. Am.
77
,
83
100
(
1985
).
23.
W.
Munk
and
C.
Wunsch
, “
Biases and caustic in long-range acoustic tomography
,”
Deep-Sea Res.
32
,
1317
1346
(
1985
).
24.
R.
Dashen
,
S. M.
Flatté
, and
S. A.
Reynolds
, “
Path-integral treatment of acoustic mutual coherence functions for ray in a sound channel
,”
J. Acoust. Soc. Am.
77
,
1716
1722
(
1985
).
25.
W. Munk, P. Worcester, and C. Wunsch, Ocean Acoustic Tomography (Cambridge University Press, Cambridge, 1995).
26.
C. S. Clay and H. Medwin, Acoustical Oceanography: Principles and Applications (Wiley, New York, 1977).
27.
C. Eckart, Hydrodynamics of the Oceans and Atmospheres (Pergamon, New York, 1960).
28.
O. M. Phillips, The Dynamics of the Upper Ocean (Cambridge University Press, Cambridge, 1977).
29.
N. P. Fofonoff, “Physical properties of sea-water,” in The Sea, Volume 1, edited by M. N. Hill (Interscience Publishers, New York, 1962), Chap. 1.
30.
C. Wunsch and B. Warren, The Evolution of Physical Oceanography (MIT Press, Cambridge, 1981).
31.
R. L. Stratanovich, Topics in the Theory of Random Noise, Vol. 1 (Gordon and Breach, New York, 1963).
32.
V. I. Tatarski, Wave Propagation in a Turbulent Medium (Dover, New York, 1961).
33.
D. L. Divins and B. Eakins, “Total sediment thickness map for the Southeast Pacific Ocean,” in Intergovernmental Oceanographic Commission, edited by G. B. Udintsev, International Geological-Geophysical Atlas of the Pacific Ocean (in press).
34.
E. L.
Hamilton
, “
Sound velocity-density relations in sea-floor sediments and rocks
,”
J. Acoust. Soc. Am.
63
,
366
377
(
1978
).
35.
E. L.
Hamilton
, “
Sound velocity gradients in marine sediments
,”
J. Acoust. Soc. Am.
65
,
909
922
(
1979
).
36.
E. L.
Hamilton
, “
Sound attenuation as a function of depth in the sea floor
,”
J. Acoust. Soc. Am.
59
,
528
536
(
1976
).
This content is only available via PDF.
You do not currently have access to this content.