Propagation of Uncertainty in Range Dependent Bellhop – Real Bathymetry, Partial Correlation, Dominant Terms, n2-linear Comparison and Gaussian Width Choices

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Authors
  1. McCammon, D.M.F.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN);McCammon Acoustical Consulting, Waterville NS (CAN)
Abstract
The Bellhop Gaussian Beam solution for acoustic propagation in an underwater environment is a complicated function of the environmental parameters of sound speed, boundary reflectivity and water depth. One of the purposes of this paper is to extend the previous derivations for the derivative with respect to sound speed uncertainty of the Gaussian Beam solution contained in McCammon, DRDC Atlantic CR 2012-100, to treat range dependence in bathymetry and bottom losses. In addition, the statistical solution for the variance of the intensity is augmented by providing for partial correlation of the sound speed uncertainties in near surface layers. In all cases tested, it is shown that the Gaussian function is the dominant term in the TL variance, and the largest variances occur whenever the ray has its turning point very near a sound speed gradient change. The derivations for the derivatives were made assuming a c-linear sound speed profile segments, so this report also examines an n2-linear sound speed profile and finds that the variances from both profile forms are qualitatively the same. Finally, the effect of Gaussian width choice on TL variance is studied.

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Report Number
DRDC-ATLANTIC-CR-2013-082 — Contract Report
Date of publication
01 Sep 2013
Number of Pages
72
DSTKIM No
CA044497
CANDIS No
804917
Format(s):
Electronic Document(PDF)

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