A computer model for generating world ocean sound velocity profile (SVP) information is presented. It employs a ’’least-squares’’ predictor to combine National Oceanographic Data Center (NODC) archival SVP data with any amount of available new sound velocity measurements that might be available. A technique is presented in the paper for the analysis of NODC World Ocean SVP data which is highly efficient. The technique is called empirical orthonormal function (EOF) analysis and it is capable of a very large compaction of the data set. This method provides a very compact presentation of the total statistical nature of the SVP data bank. The end result is a computer model which permits the optimum utilization of all archival data and any new data at a given place and time in world oceans to produce a new complete SVP. Of even greater significance is the fact that the form of the predicted SVP profile is such that it is easily employed in any propagation loss prediction model that is currently in use.
A recently developed technique is investigated for the analysis of sea floor acoustic reflection data. The technique uses Empirical Orthonormal Functions (EOF’s) to analyze the entire acoustic echo from the sea floor. In previous work [Milligan et al., J. Acoust. Soc. Am. 64, 795–807(1978)], the technique was used to ’’cluster’’ areas of similar acoustic behavior. This paper explores the relationship between the acoustic behavior of a sea floor sediment and classical engineering measurements. To achieve the objective, an experiment was configured so as to obtain acoustic reflection data and sediment measurements at the same spot on the sea floor. The results of this analysis showed that significant correlation exists between the acoustic waveform and certain measured sediment properties, and that an acoustic sediment classification scheme can be implemented.
The problem of long range propagation in a continuously stratified medium is considered for those cases where the stratification is such that a region of slow sound velocity is found to be embedded in a region of relatively faster sound velocity. It is then possible to explain the guiding mechanism of the medium in terms of surface-wave theory. The technique employed utilizes an equivalent integral-equation representation for the differential equations describing the boundary-valve problem, and yields information concerning the dispersive character of the medium. As a means of illustrating the mechanics of this technique and demonstrating its application, dispersion curves are obtained for the particular case of propagation in the sofar sound channel.
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