Layered oceanic microstructure—its effect on sound propagation

Abstract

It has recently been established that the vertical profiles of oceanographic parameters in the seasonal and permanent thermocline regions are not the smooth curves observed by older techniques. Rather they indicate a large number of nearly homogeneous layers, with typical thicknesses of meters or less, separated by interfacial regions where strong gradients exist. Examples of typical layered microstructure profiles from different ocean areas are presented. The effects of such microstructure on sound propagation are examined qualitatively using ray tracing techniques. It was found that the layered microstructure had a significant effect only when rays vertex within the layers, in which case the isointensity loss contours degenerate into a broad scatter of points.