Propagation through a three-dimensional eddy including effects on an array

Baer, Ralph N.

doi:10.1121/1.385253

Cited by 47 publications

(13 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The perturbation might be considered a very simple model of an eddy. 19,21,32 The geometry of the cylindrical perturbation is illustrated in Fig. 6, from both a top view ͑a͒ and a perspective view ͑b͒.…”

Section: Effect Of a Compact Cylindrical Perturbation On Pressure Derivativementioning

confidence: 99%

The derivative of a waveguide acoustic field with respect to a three-dimensional sound speed perturbation

Thode

2004

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

Semianalytic expressions are derived for the first-order derivative of a pressure field in a laterally homogeneous waveguide, with respect to an arbitrary three-dimensional refractive index perturbation in either the water column or ocean bottom. These expressions for the ''environmental derivative,'' derived using an adjoint method, require a three-dimensional spatial correlation between two Green's functions, weighted by an environmental parameter basis function, with the Green's functions expressed in terms of normal modes. When a particular set of orthogonal spatial basis functions is chosen, the three-dimensional spatial integral can be converted into a set of one-dimensional integrations over depth and azimuth. The use of the orthogonal basis permits environmental derivatives to be computed for an arbitrary sound-speed perturbation. To illustrate the formulas, a simple sensitivity study is presented that explores under what circumstances three-dimensional plane-wave and cylindrical perturbations produce non-negligible horizontal refraction effects, for a fixed source/receiver geometry. Other potential applications of these formulas include benchmarking three-dimensional propagation codes, and computing Cramer-Rao bounds for three-dimensional environmental parameter estimates, including internal wave components.

show abstract

Section: Effect Of a Compact Cylindrical Perturbation On Pressure Derivativementioning

confidence: 99%

The derivative of a waveguide acoustic field with respect to a three-dimensional sound speed perturbation

Thode

2004

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

show abstract

“…Since the inception of ocean acoustic tomography over 30 years ago (Munk et al, 1995), it has been known that the horizontal deviation of acoustic signals sent between a source and a receiver from the geodesic path is minimal (Baer, 1981;Munk, 1980). Indeed, undersea surveilance systems employing acoustics to determine the locations of targets of any kind implicitly rely on the fact that the horizontal refraction of the acoustic signals can be neglected.…”

Section: Introductionmentioning

confidence: 98%

Assessing the horizontal refraction of ocean acoustic tomography signals using high-resolution ocean state estimates

Dushaw

2014

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

The analysis of signals for acoustic tomography sent between a source and a receiver most often uses the unrefracted geodesic path, an approximation that is justified from theoretical considerations, relying on estimates of horizontal gradients of sound speed, or on simple theoretical models. To quantify the effects of horizontal refraction caused by a realistic ocean environment, horizontal refractions of long-range signals were computed using global ocean state estimates for 2004 from the Estimating the Circulation and Climate of the Ocean (ECCO2) project. Basin-scale paths in the eastern North Pacific Ocean and regional-scale paths in the Philippine Sea were used as examples. At O(5 Mm) basin scales, refracted geodesic and geodesic paths differed by only about 5 km. Gyre-scale features had the greatest refractive influence, but the precise refractive effects depended on the path geometry with respect to oceanographic features. Refraction decreased travel times by 5-10 ms and changed azimuthal angles by about 0.2°. At O(500 km) regional scales, paths deviated from the geodesic by only 250 m, and travel times deviated by less than 0.5 ms. Such effects are of little consequence in the analysis of tomographic data. Refraction details depend only slightly on mode number and frequency.

show abstract

“…[7][8][9][10][11][12][13][14][15] They have been used to compute propagation in a number of three-dimensional environments and to show acoustical effects not predicted by any 2D model. However, the bottom slopes (both in range and azimuth) are generally handled using a stair-step approximation, i.e.…”

Section: Introductionmentioning

confidence: 99%

Accurate Treatment of a General Sloping Interface in a Finite-Element 3d Narrow-Angle Pe Model

Cnrs

Kampanis

2007

J. Comp. Acous.

View full text Add to dashboard Cite

Parabolic equation models in 3D usually apply the "staircase" approximation to general rangevarying interfaces between adjacent layers. This is the simplest technique available: it consists in neglecting range and azimuthal derivatives in the associated interface conditions. Our aim in this paper is to analyze the influence of the stair-step approximation technique, common to most 3D PE models, on a one-way sound wave propagation problem. We present a new finite-element 3D narrowangle PE model which accurately treats the variable interface conditions. This is accomplished by using (i) an appropriate parabolized condition of the same aperture as the parabolic equation used, and (ii) a new change-of-variable technique which does not require any homotheticity condition of the layers as in previous works. Numerical simulations for the 3D wedge problem are presented. The convergence of the numerical solutions with respect to the azimuth is investigated. Unlike other 3D PE models working in cylindrical coordinates, the convergence tests have been carried out using a range-dependent number of points in azimuth. Numerical solutions obtained with the newly developed model are compared with a reference solution based on the image source and with a solution obtained with a 3D PE model that uses a stair-step technique.

show abstract

Propagation through a three-dimensional eddy including effects on an array

Cited by 47 publications

References 0 publications

The derivative of a waveguide acoustic field with respect to a three-dimensional sound speed perturbation

The derivative of a waveguide acoustic field with respect to a three-dimensional sound speed perturbation

Assessing the horizontal refraction of ocean acoustic tomography signals using high-resolution ocean state estimates

Accurate Treatment of a General Sloping Interface in a Finite-Element 3d Narrow-Angle Pe Model

Contact Info

Product

Resources

About