### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 3aUW12. Saturated ocean acoustic intensity statistics as a function of
temporal coherence and measurement time.

**Nicholas C. Makris
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*Naval Res. Lab., Washington, DC 20375
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Coherence theory is used to analyze the statistics of saturated ocean
acoustic intensity measurements. The circular complex Gaussian random field
assumption has been used to describe saturated multipath propagation in the
ocean for many years. However, previous analysis of intensity statistics in the
saturated region have implicity been limited to certain special cases for which
the time-bandwidth product of the field measured from a given source is unity.
In this paper, the intensity statistics in the saturated region are extended and
generalized to be a function of measurement time and temporal coherence. As a
result, the well-known 5.6-dB transmission loss (TL) standard deviation of Dyer
is found to be a special case of a more general TL standard deviation that
approximates 4.34[radical 1/(mu)[radical dB when the time-bandwidth product or
number of independent samples (mu) of the intensity average is large. Therefore,
the TL standard deviation is shown to approach zero when the time-bandwidth
product becomes large, as it must in this deterministic limit. A similar
generalization is obtained for the TL mean. Additionally, asymptotic analysis
shows that the log-normal distribution for intensity can provide an excellent
approximation to TL statistics, contrary to previous contentions.