Effect of Bottom Properties in Acoustic Distance Measurement on the Shallow-Water Arctic Shelf

The impact of seabed characteristics on the accuracy in determining the distance between a sound source and receiver located underwater was studied by numerical experiments. Experimental data on bottom parameters and the sound speed profile in the water layer in the (hydrological) summer and winter in the shallow-water part of the Kara Sea were used. In the latter case, the effect of ice cover was taken into account. It has been found that the main error in determining the distance in the 1–10 km interval is associated with the multimode (multiray) nature of the acoustic wave propagation in the sound channel between the water surface and bottom. It has been demonstrated that this error decreases to several meters in summer and with a waterlike bottom, when the sound speeds in the water layer and bottom are close to each other. It has been noted that horizontal refraction of acoustic waves caused by the transverse inhomogeneity of the bottom also leads to errors in determining distance, although to a lesser extent.