A. Yu. Shmelerv A. A. Migulin
Inst. of General Phys., Russian Acad. of Sci. and Ocean Acoust. & Information Ltd., 38 Vavilov St., Moscow, 117942, Russia
James F. Lynch
Woods Hole Oceanogr. Inst., Woods Hole, MA 02543
Previous work by Petnikov [Akust. Zh. 37, 1212--1215 (1991)] and Shmelerv et al. [J. Acoust. Soc. Am. 92, 1003--1007 (1992)] has shown fast phase fluctuations of up to 180(degrees) in low-frequency continuous-wave (cw) signals measured during the Coastal Barents Sea Acoustic Test Experiment. These fast fluctuations can be explained as phase dislocations passing through the receiving array [Kravtsov et al., Sov. Phys. Acoust. 35, 156--159 (1989)]. Recent investigations of linearly modulated broadband acoustic signal propagation in the same region have also shown some features associated with phase dislocations passing by. It was found that the frequency at which a dislocation occurs changes slightly because of ocean variability. This frequency can be considered as a parameter of the acoustic field variability. The results of experimental observations of phase dislocations in several shallow water cw and broadband experiments are summarized. Discussion of these experiments will include suggestions on the use of the dislocation approach in tomographic schemes.