Reprints: Recent submissions
Now showing items 381-400 of 548
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A fast field model for three-dimensional wave propagation in stratified environments based on the global matrix method
(NATO. SACLANTCEN, 1986/03)A three-dimensional fast field program (FFP) model based on the global matrix method will be presented. Compared to traditional propagator matrix methods, the global matrix method allows for a more efficient, and, furthermore, ... -
Underwater photography for quantitative description of bottom roughness
(NATO. SACLANTCEN, 1985/04)Knowledge of the roughness of the sea floor is obviously of great importance in marine geology for understanding the processes of the ocean bottom, and in underwater acoustics for understanding the scattering process. The ... -
Review of numerical models in underwater acoustics including recently developed fast-field program
(NATO. SACLANTCEN, 1984/12)Two papers given by SACLANTCEN personnel at the NATO Advanced Research Workshop on Hybrid Formulation of Wave Propagation and Scattering at Castel Gandolfo, Rome, Italy on 30 August to 3 September 1983 are published as a ... -
An evaluation of digitized APT data from the TIROS-N/NOAA-A, -J series of meteorological satellites
(NATO. SACLANTCEN, 1984/03)The TIROS-N/NOAA-A,-J series of meteorological satellites transmit imagery data to the Earth in both digital and analogue formats. The analogue data are a processed subset of the digital dat and have lower resolution. A ... -
Variable sea level and strait flows in the Mediterranean: a theoretical study of the response to meteorological forcing
(NATO. SACLANTCEN, 1983/05)Changes in atmospheric pressure over the Mediterranean are thought to account for a significant part of low frequency sea level changes and associated flow through the Strait of Gibraltar. However, Crepon's (1965) examination ... -
Use of the towship for assessing towed-array performance and analyzing data quality
(NATO. SACLANTCEN, 1982/11)A series of relatively simple tests are presented and discussed, which used in conjunction with the noise received from the towship, can be used in real time to assess the performance of a towed array and the quality of ... -
High-frequency normal-mode calculations in deep water
(NATO. SACLANTCEN, 1982/10)A method has been developed to perform high-frequency deep-water normal-mode calculations in the multikilohertz region in water depths of the order of 5 km. The results from this technique agree with fast field program ... -
The optimum frequency of propagation in shallow-water environments
(NATO. SACLANTCEN, 1983/04)The optimum frequency of propagation in shallow water environments is the result of competing propagation and attenuation mechanisms at high and low frequencies. It is shown that the optimum frequency is strongly dependent ... -
Sound propagation in shallow water: a detailed description of the acoustic field close to surface and bottom
(NATO. SACLANTCEN, 1982/02)Experimental data are compared with normal-mode predictions for an isovelocity shallow-water propagation channel overlying a complicated layered bottom. Measurements were made close to both the sea surface and the sea floor ... -
Range and depth estimation by line arrays in shallow water
(NATO. SACLANTCEN, 1982/01)In shallow water sound propagates in terms of normal modes. The interference between the modes can be utilized to estimate range and depth of an acoustic source in shallow water by applying high resolution power estimators ... -
Spatial correlation of surface-generated noise in a stratified ocean
(NATO. SACLANTCEN, 1980/10)A model is developed for the calculation of the spatial properties of the noise field produced in a stratified ocean by the action of wind at the surface. The random noise sources are represented by correlated monopoles ... -
Position and shape of the surface shadow zone
(NATO. SACLANTCEN, 1971/12)From surface reverberation studies conducted by SACLANTCEN's Target Classification Group"C , it has been found necessary to know before any sea experiment the precise position of the first surface shadow zone. Since normal ... -
Deterministic propagation modelling: Part 1: Fundamental principles *Part 2: Numerical results
(NATO. SACLANTCEN, 1981/06)The physics of sound propagation in the ocean is briefly reviewed. The wave equation is presented and a set of solutions under a variety of approximations is discussed. The consistency among these solutions is illustrated. -
Low-frequency ambient noise in the deep sound channel: the missing component
(NATO. SACLANTCEN, 1981/07)There is an important component of the undersea ambient noise which has generally been overlooked or ignored. It is the noise which arrives at a sensor, located in a deep sound channel, by way of ducted sound propagation. ... -
Variability in the Gulf of Cadiz: internal waves and globs
(NATO. SACLANTCEN, 1980/08)An experiment was performed in the Gulf of Cadiz during June 1977, with the objective of separating oceanic variability due to internal waves from that due to inhomogeneities of the water. A CTD which oscillates in depth ... -
Two-dimensional space-series analysis for sea-floor roughness
(NATO. SACLANTCEN, 1979/10)For a quantitative description of the sea-floor roughness, a numerical method has been developed to obtain the two-dimensional power spectrum and the autocorrelation function. The determination of these parameters gives ... -
Sound propagation in a wedge-shaped ocean with a penetrable bottom
(NATO. SACLANTCEN, 1980/07)Modal cutoff during up-slope propagation in a wedge-shaped ocean is studied using the parabolic equation model; theoretical results are compared with some model tank experiments. -
Intensity-range relations for shallow-water sound propagation
(NATO. SACLANTCEN, 1976/04)Convincing experimental evidence is presented to show that various "decay laws" for the decrease of sound intensity with increasing range can give high-quality representation for shallow water data. However, while a sequence ... -
The steady state of the step structure in the Tyrrhenian Sea
(NATO. SACLANTCEN, 1978/10)A deep step structure, in which mixed layers alternate with high gradient interfaces, is a characteristic feature of the Tyrrhenian Sea. Three oceanographic cruises (May 1972, May 1973 and October 1974), supported by the ... -
Model for the frequency spread of backscattered underwater sound based on the facet model of the rough sea surface
(NATO. SACLANTCEN, 1978/11)A theoretical model for the doppler spread of backscattered acoustic waves from the rough sea surface is described on the basis of the decomposition of the continuous sea-surface spectrum that leads to the concept of facets. ...