IEEE Organizations related to Sea Floor Roughness

Back to Top

No organizations are currently tagged "Sea Floor Roughness"



Conferences related to Sea Floor Roughness

Back to Top

No conferences are currently tagged "Sea Floor Roughness"


Periodicals related to Sea Floor Roughness

Back to Top

No periodicals are currently tagged "Sea Floor Roughness"


Most published Xplore authors for Sea Floor Roughness

Back to Top

Xplore Articles related to Sea Floor Roughness

Back to Top

Effects of Small Scale Seafloor Roughness on Acoustic Reflectivity Measurements on the Newfoundland Shelf

OCEANS '87, 1987

In the last decade there has been a continued interest in the use of acoustic properties, in particular the amplitude of seismic reflections, for the prediction of the physical characteristics of marine sediments. These techniques generally assume a plane wave reflection from a smooth seafloor and do not utilise the contribution of energy scattered from a rough surface. The effect ...


Characteristics of ocean bottom roughness for several seamounts derived from multibeam bathymetric data

OCEANS '85 - Ocean Engineering and the Environment, 1985

Multibeam bathymetric systems offer to revolutionize our understanding of the ocean bottom and its major structural features by providing highly detailed measurements of the bottom. Further, multibeam measurements yield bottom depth as a function of both spatial coordinates (i.e. along-track and across-track). The depth resolution is sufficiently fine that conventional contour charts would never incorporate all the information available in ...


Models for seafloor roughness and volume scattering

IEEE Oceanic Engineering Society. OCEANS'98. Conference Proceedings (Cat. No.98CH36259), 1998

Models for seabed volume and roughness scattering at high and lower frequencies are presented. The sediment is considered as a fluid medium with rough interfaces and spatial fluctuations of the density and sound speed. At high frequencies, the mean parameters of bottom medium are considered as independent from spatial coordinates due to small penetration of sound into the sediment. At ...


Comparison of multilayer perceptrons and maximum likelihood processors in the context of seafloor parameter estimation

Proceedings of OCEANS '93, 1993

The objective of this work is acoustic seafloor characterization based on the statistical properties of bottom reverberation. The seafloor roughness parameters are related to backscattering strength through the Helmoltz- Kirchhoff scattering model. These parameters are estimated through the application of multilayer perceptrons and maximum likelihood (ML) estimators to synthetic backscatter representing seafloor with different morphology. The multilayer perceptron is presented ...


Small scale seafloor roughness measurement using a ROV

MTS/IEEE Oceans 2001. An Ocean Odyssey. Conference Proceedings (IEEE Cat. No.01CH37295), 2001

A method for seafloor roughness measurement was devised for a remotely operated vehicle (ROV), consisting of lasers and a video camera. It was designed to measure small-scale roughness in the range of spatial wavelengths from 0.01 to 1 m. This range of wavelengths is expected to be relevant to acoustic bottom backscattering in the frequency range roughly from 1 to ...


More Xplore Articles

Educational Resources on Sea Floor Roughness

Back to Top

IEEE-USA E-Books

  • Effects of Small Scale Seafloor Roughness on Acoustic Reflectivity Measurements on the Newfoundland Shelf

    In the last decade there has been a continued interest in the use of acoustic properties, in particular the amplitude of seismic reflections, for the prediction of the physical characteristics of marine sediments. These techniques generally assume a plane wave reflection from a smooth seafloor and do not utilise the contribution of energy scattered from a rough surface. The effect of seafloor roughness on the spectral content of seafloor echoes produced by a boomer profiling system (the Huntec Deep Towed High Resolution Seismic System) are discussed in this paper, Estimates of roughness using shot to shot coherence at discrete positions are compared to roughness obtained from a suite of bottom photographs. Information of a more regional nature have been obtained by display of the seismic profile along with reflectivity parameters and coherence functions.

  • Characteristics of ocean bottom roughness for several seamounts derived from multibeam bathymetric data

    Multibeam bathymetric systems offer to revolutionize our understanding of the ocean bottom and its major structural features by providing highly detailed measurements of the bottom. Further, multibeam measurements yield bottom depth as a function of both spatial coordinates (i.e. along-track and across-track). The depth resolution is sufficiently fine that conventional contour charts would never incorporate all the information available in the multibeam data. As an alternative to such deterministic presentations, it can be suggested that statistical characterizations be developed for topographic variability at horizontal scales which are small in comparison to the overall dimensions of the feature of interest. We here discuss the study of rough topography on several seamounts by means of multibeam bathymetry. The bottom topography is analyzed in terms of numerous samples of1600 m \times 1600m extent. A primary quantity of interest is the rms value of the residual topography. The pattern of variability for the rms values is described for several seamounts and shown to have certain overall similarities.

  • Models for seafloor roughness and volume scattering

    Models for seabed volume and roughness scattering at high and lower frequencies are presented. The sediment is considered as a fluid medium with rough interfaces and spatial fluctuations of the density and sound speed. At high frequencies, the mean parameters of bottom medium are considered as independent from spatial coordinates due to small penetration of sound into the sediment. At lower frequencies, seabeds are assumed as statistically stratified (plane-layered on the average) with the mean parameters taken as various functions of depth. As numerical examples, angular dependencies of the scattering strength are calculated for seabeds of various types.

  • Comparison of multilayer perceptrons and maximum likelihood processors in the context of seafloor parameter estimation

    The objective of this work is acoustic seafloor characterization based on the statistical properties of bottom reverberation. The seafloor roughness parameters are related to backscattering strength through the Helmoltz- Kirchhoff scattering model. These parameters are estimated through the application of multilayer perceptrons and maximum likelihood (ML) estimators to synthetic backscatter representing seafloor with different morphology. The multilayer perceptron is presented with synthetic sequences and is instructed to yield the parameters of interest in the output. ML estimation relies on the construction of a rectangular grid that maps scattering strength vectors to the two parameters under estimation through the Helmholtz-Kirchhoff model. The parameter estimates are the coordinates of the grid element at which the likelihood function-calculated for sets of simulated observations-obtains a maximum. The performance of both estimation processors is determined by the mean and variance of the obtained parameter estimates.<>

  • Small scale seafloor roughness measurement using a ROV

    A method for seafloor roughness measurement was devised for a remotely operated vehicle (ROV), consisting of lasers and a video camera. It was designed to measure small-scale roughness in the range of spatial wavelengths from 0.01 to 1 m. This range of wavelengths is expected to be relevant to acoustic bottom backscattering in the frequency range roughly from 1 to 100 kHz, depending on grazing angle and orientation.

  • Maximum a posteriori probability estimation of seafloor microroughness parameters from backscatter spatial coherence

    A technique is presented for the estimation of a set of parameters associated with a geologically motivated model for seafloor microroughness due to Goff and Jordan (1988). The method seeks to connect the spatial covariance of the backscattered acoustic field with the correlation properties of the seafloor by constructing the a posteriori probability density function (pdf) of the parameters that define the seafloor microroughness wavenumber spectrum. The processor maximizes the joint a posteriori probability density of the model parameter set. Due to the complexity of the probability surface, the method of simulated annealing is used to search for the globally optimum solution vector.

  • Statistical characterization of multibeam echosounder data

    The statistical studies of high resolution sonar images recorded by a 95 kHz multibeam echosounder prove that the Rayleigh law is no more adapted to the description of the textured sonar images. Seafloor reverberation statistical models have been put forward to interpret those high resolution particularities and to propose the correlated K-law distributions. Moreover, the author takes advantage of the multibeam echosounder geometry to highlight a change of the sonar image statistics with the insonified area and with the transmission angle. A rigorous interpretation of the image spectral and statistical properties must account for the acquisition process geometry.

  • A wedge diffraction based scattering model for acoustic scattering from rough littoral seafloors

    Models for acoustic scattering from rough surfaces based on Biot and Tolstoy's (BT) exact wedge diffraction theory have proven accurate and useful in a number of experimental and numerical studies [1]. Because the BT solution is restricted to impenetrable wedges (acoustically hard or soft boundary conditions), scattering models based on the BT solution have thus far been limited to the rough air/sea interface where the actual boundary conditions are very nearly pressure-release (soft). Recently, important theoretical work [2,3] has extended the exact BT theory to density-contrast but isospeed wedges. This new development makes possible the application of wedge diffraction based scattering models to the roughness at the sea floor where the change in the acoustic impedance at the boundary is dominated by changes in density and only weakly affected by changes in sound speed. However, it is important to confirm that small amounts of sound speed contrast do not perturb the diffraction too much. To contribute to the understanding of how the diffracted wave is affected by sound speed contrast and get some idea as to the practical limitations of wedge-diffraction based scattering models for littoral seafloors, a simple numerical experiment involving a highly accurate Finite-Difference Time-Domain (FDTD) solution to the acoustic wave equation and a wedge-shaped boundary has been explored. This paper presents the results of FDTD experiments designed to quantify any changes in the diffracted field brought about by sound speed contrast. An ad hoc treatment of sound speed contrast is developed based on the requirement that the diffracted wave must smooth out the reflection discontinuity and preserve the continuity of the total field.

  • Bottom classification in very shallow water by high-speed data acquisition

    Bottom classification based on echo features and multivariate statistics is now a well established procedure for habitat studies and other purposes, over a depth range from about 5 m to over 1 km. Shallower depths are challenging for several reasons. To classify in depths of less than a metre, a system has been built that acquires echoes at up to 5 MHz and decimates according to the acoustic situation. The digital signal processing accurately maintains the echo spectrum, preventing aliasing of noise onto the signal and preserving its convolution spectral characteristics. Sonar characteristics determine the minimum depth from which quality echoes can be recorded. Trials have been done over sediments characterized visually and by grab samples, in water as shallow as 0.7 m.

  • Measurement of seafloor roughness with close range digital photogrammetry

    SACLANT Undersea Research Centre has recently developed a close range photogrammetry system which uses stereo images of the seafloor and photogrammetric processing techniques to produce surface elevation models in a digital format. In this paper is given a description of the fully digital system and examples of high-resolution seafloor height data extracted from stereo photographs taken on a sandy seafloor near Elba Island, Italy. Preliminary results indicate that the system described will be able to give fast and accurate estimates of small scale bottom topography that will ultimately enhance studies of the seafloor and acoustic scattering due to seafloor roughness.



Standards related to Sea Floor Roughness

Back to Top

No standards are currently tagged "Sea Floor Roughness"


Jobs related to Sea Floor Roughness

Back to Top