Azimuthal, spatial, and temporal variability of acoustic intensity in cross-shelf direction during the yearlong shallow water Canada Basin Acoustic Experiment 2016–2017

A yearlong study of spatial, temporal, and azimuthal variability of sound propagation with simultaneously measured oceanography on Chukchi shelf is reported. In a shallow water region, two acoustic sources were deployed for studying the “along” and “cross-shelf” propagation. The “along-shelf” study is presented separately [J. Ascout. Sci. Am. 145 (2019)]. Here, we focus on the “cross-shelf” signal propagation in two frequencies (0.7–1.1 and 1.5–4 kHz) transmitted from a single sound source placed near the sound channel axis in 320 m water depth. Three “cross-shelf” acoustic tracks connected the source and three receiver arrays placed along 50 m isobath. The angle between east most and west most tracks was around 106 deg. Another array at 250 m isobath was deployed along the middle track. Sound emitted from the common source shows different behavior along each track. Concurrently, detailed water column salinity and temperature were measured by environmental arrays in both “along” and “cross-shelf” directions. Sea surface ice was measured by an upward looking sonar for several months. Seasonal injection of different water masses in this region and variations of sea surface conditions (full-ice, transition, and free-surface) are examined using the acoustical oceanographic data. This paper quantifies analysis using correlation between acoustics and oceanographic signals. [Work supported by ONR 322OA.]