Publication Date:
2022-05-25
Description:
Author Posting. © Acoustical Society of America, 1999. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 105 (1999): 3185, doi:10.1121/1.424649.
Description:
Broadband acoustic signals were transmitted during November 1994 from a 75-Hz source suspended near the depth of the sound-channel axis to a 700-m long vertical receiving array approximately 3250 km distant in the eastern North Pacific Ocean. The early part of the arrival pattern consists of raylike wave fronts that are resolvable, identifiable, and stable. The later part of the arrival pattern does not contain identifiable raylike arrivals, due to scattering from internal-wave-induced sound-speed fluctuations. The observed ray travel times differ from ray predictions based on the sound-speed field constructed using nearly concurrent temperature and salinity measurements by more than a priori variability estimates, suggesting that the equation used to compute sound speed requires refinement. The range-averaged oceansound speed can be determined with an uncertainty of about 0.05 m/s from the observed ray travel times together with the time at which the near-axial acoustic reception ends, used as a surrogate for the group delay of adiabatic mode 1. The change in temperature over six days can be estimated with an uncertainty of about 0.006 °C. The sensitivity of the travel times to ocean variability is concentrated near the ocean surface and at the corresponding conjugate depths, because all of the resolved ray arrivals have upper turning depths within a few hundred meters of the surface.
Description:
This work was
supported largely by the Strategic Environmental Research
and Development Program through Defense Advanced Research
Projects Agency ~DARPA! Grant No. MDA972-93-
1-0003. Additional support was provided at SIO by the Office
of Naval Research ~ONR! through Grant No. N00014-
97-1-0258. J. Colosi wishes to acknowledge support from an
ONR Young Investigator Award, from the J. Lamar Worzel
Assistant Scientist Fund, and from the Penzance Endowed
Fund in support of scientific staff at WHOI.
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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