Multi-Modal and Short-Range Transmission Loss in Ice-Covered, Near-Shore Arctic Waters

• Main Author: Penhale, Miles B.
• Format: Text
• Language: unknown
• Published: Digital Commons @ Michigan Tech 2017
• Subjects: Frequency Response Function; Transmission Loss; Shore Fast; Arctic; Thin Ice; Attenuation; Acoustics; Dynamics; and Controls; Ocean Engineering; Oceanography; Other Physical Sciences and Mathematics; Barrow; Alaska
• Online Access: https://digitalcommons.mtu.edu/etdr/453; https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1519&context=etdr

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. One of the most commonly used excitation methods for air-ice-water layers has been explosives. However, environmental regulation has become more stringent, disallowing the use of almost all explosive excitation types. Due to changing climate conditions in these environments, new experimentation is warranted to determine sound propagation characteristics in, through, and under 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 (FRFs) 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 characteristics of the multipath propagation (air, ice, water) are investigated and reported.