Dependence of low-frequency backscatter on the size and orientation of lineal Arctic scatterers

The backscatter of low-frequency underwater sound from the Arctic ice canopy is generally caused by leads and ridges of a vast variety of sizes, orientations. and spacings. Laboratory scale-model experiments, guided by the theory of sound diffraction from wedges, have been used to determine the dependence of low-frequency backscatter on the geometrical parameters. The specific variation with the orientation and length of the lineal scatterer is demonstrated, and it is shown that the predominant scatter occurs when there is a section of the lead or ridge that is azimuthally perpendicular to the sound path. [Work supported by ONR.]