### ASA 126th Meeting Denver 1993 October 4-8

## 5aUW11. Analysis of the acoustic field via spectral decomposition.

**Guy V. Norton
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*NRL-SSC, Stennis Space Center, MS 39529-5004
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Spectral decomposition has been used by various authors as a calculation
technique for acoustic propagation in range independent and recently range
dependent ocean environments. One of the methods' strong points is that it maps
the initial acoustic field at each given depth point in the waveguide into
horizontal wavenumber space. Since the field is now expressed in wavenumber
space, analogous to normal mode theory, various acoustic quantities can easily
be calculated. These quantities such as the group velocity or the incident
field expressed in terms of the plane wave spectrum in the past were calculated
using normal modes. However, since all that is required to initiate the method
is a complex acoustic field evenly space in depth of the waveguide, the method
has been coupled to the output of a PE model, in order to analyze that field.
The associated theory and numerical examples will be given. [Work sponsored by
ONR.]