Identification of the acoustic ocean transfer function in the Tyrrhenian Sea. II: Physical considerations

Abstract

In the process of statistical analysis of signature/response pairs collected in the Tyrrhenian Sea during the Napoli 85 Trial, a novel deconvolution method has been developed for identifying the ocean transfer function (OTF) when its bandwidth is larger than the bandwidth of the emitted pulse. The analysis itself is described in the preceding paper [L. Ju. Fradkin, J. Acoust. Soc. Am. 87, XXXX (1990)]. Here, the underlying convolution formula relating the received signal to the signature as well as other important physical constraints are derived under the assumptions (reasonable in the analyzed case) that the emitted pulse contains no low frequencies, and that it travels along the paths none of which reverses the phase (i.e., no reflections or caustics are involved). The results of processing a representative signature/response pair with the proposed method are discussed briefly. It is shown that for the given source/receiver configuration at least two deep sea (and hence non-phase-reversing) paths exist. It is also shown that the ‘‘internal waves’’ model, rejected by other investigators in the course of their analysis of the environmental data, would not allow for existence of the second macropath. It is concluded that in certain circumstances, the proposed deconvolution method could be used to assess models of medium fluctuations.