Multi-modal and short-range transmission loss in thin, ice-covered, near-shore Arctic waters.

In the past century, extensive research has been done regarding the sound propagation in Arctic ice sheets. The majority of this research has focused on low-frequency propagation over long distances. Due to changing climate conditions in these environments, experimentation is warranted to determine sound propagation characteristics in, through, and under first-year, thin ice sheets, in shallow water, over short distances. In April 2016 several experiments were conducted approximately 2 km off the coast of Barrow, Alaska on shore-fast, first-year ice, approximately 1 m thick. To determine the propagation characteristics of various sound sources, frequency response functions were measured between a source location and several receiver locations at various distances from 1 m to 1 km. The primary sources used for this experiment were, an underwater speaker with various tonal outputs, an instrumented impact hammer on the ice, and a propane cannon that produced an acoustic blast wave in air. The transmission loss (TL) characteristics of the multipath propagation (air, ice, water) are investigated and reported. Data indicate that TL in frequency bands between 125 and 2000 Hz varied from approximately 3-6 dB per doubling of distance which is consistent with geometrical spreading losses, cylindrical and spherical, respectively.