Spatial and temporal fluctuations using the parabolic profile

Abstract

Calculations have been performed using the normal-mode solutions to the parabolic sound-speed profile to estimate the fluctuations in a low-frequency CW acoustic signal transmitted over large distances in the deep ocean. Temporal fluctuations are estimated by fixing the source and receiver and allowing the profile to vary in such a manner as to approximate the effect of the first mode 12.42-h internal tide propagating in a direction perpendicular to the source/receiver line. Spatial fluctuations are estimated by allowing the source to move at constant speed through a frozen ocean at approximately the same range as that used for temporal fluctuations. Preliminary results indicate that although both spatial and temporal fluctuations may be of approximately the same magnitude, the spatial fluctuations even at a moderate source speed of 7 knots occur at a much more rapid rate than do the temporal fluctuations.