3pUW3. Coherence of acoustic modes passing through internal solitary waves.

Session: Wednesday Afternoon, December 3


Author: James C. Preisig
Location: Dept. of Appl. Ocean Phys. and Eng., MS 11, Woods Hole Oceanogr. Inst., Woods Hole, MA 02543
Author: Timothy F. Duda
Location: Dept. of Appl. Ocean Phys. and Eng., MS 11, Woods Hole Oceanogr. Inst., Woods Hole, MA 02543

Abstract:

Packets of internal solitary waves can affect coherence between acoustic modes propagating in shallow water. Shallow water is characterized as having less than 10 or 15 propagating modes, including the influence of an attenuating bottom. Previous work has shown that individual internal waves or packets of waves can scatter low-mode energy into higher modes. Prior results and intuition indicate that the higher modes attenuate more quickly through boundary interaction. The propagation of the internal waves, which couple energy between the modes, can rapidly influence the relative amplitudes and phases of the modes. Numerical simulations are used here to quantify the effects which the relative positions of the source, receiver, and wave packet (or packets) have on the mode coherence. Of particular interest are packets of solitary waves near the source, which can amplify the source. Frequencies of a few hundred Hz and propagation over tens of km are investigated. The results are compared with experimental data. [Work supported by ONR Ocean Acoustics.]


ASA 134th Meeting - San Diego CA, December 1997