| Popis: |
Based upon the concept of the interference invariant, the variability in the interference pattern of sound fields in shallow water is described. We have considered the variability in the frequency domain (frequency shift of interference extremum) caused by large‐scale hydrodynamic perturbations. In particular, we have estimated the frequency shift produced by tides, internal waves, surface waves, and diurnal oscillations of the frontal zone. Similar variations of interference pattern can be measured along an invariable acoustic track with stationary sound sources and receivers. The feasibility of such measurements are discussed. Observational data for the frequency shifts of the interference pattern in the Barents Sea are presented and their interpretation is given. It was demonstrated that the measurements of the frequency shifts can be used for monitoring shallow water ocean regions at short distances. To do this, we propose to transmit and receive single‐type modes of underwater sound channels which are sensitive to one or another hydrodynamic perturbations. It is essential that extended vertical arrays should be used. |
