Alaska North Shore Ocean Acoustics Study

• Main Author: Lin,Ying-Tsong
• Other Authors: Woods Hole Oceanographic Institution Woods Hole United States
• Format: Text
• Language: English
• Published: 2015
• Subjects: Acoustics; Physical and Dynamic Oceanography; ALASKA; underwater acoustics; ARCTIC OCEAN; acoustic propagation; ambient noise; ice; wind; UPWELLING; CONTINENTAL SHELVES; OCEAN CURRENTS; bathymetry; climate change; pacific ocean; observation; models; measurement; elastic properties; equations of motion; PARTIAL DIFFERENTIAL EQUATIONS; algorithms; hydrophones; underwater sound; ocean acoustics; Alaska North Shore; shelfbreaks; ice cover; halocline sound ducts; shelfbreak circulation; seabed variations; sea ice; Canada Basin; Beaufort Sea; pe (parabolic-equation); pe method; canap (Canada Basin Acoustic Propagation Experiment); SHRU (Several Hydrophone Receiver Unit); Arctic; Arctic Ocean; Canada; Pacific; Beaufort Shelf; canada basin; Chukchi; Climate change; Sea ice; Alaska
• Online Access: http://www.dtic.mil/docs/citations/AD1024347; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD1024347

The changing Arctic climate has been altering air-sea interaction and physical oceanographic conditions in the regions. The long-term goals of this project is to acquire better understanding of the effects of changing ice cover, wind patterns and circulation/upwelling on underwater sound propagation and ambient noise in the areas of continental shelves and shelfbreak on Alaska north shore. The potential relevance of this work to the Navy is on increasing the capability of Naval sonar systems in Arctic oceans. The overall research goal of our study is to understand the physical effects of the changing oceanographic conditions in Arctic oceans on sound propagation and ambient noise, and the focuses are on the influences of (1) ice cover, (2) halocline sound ducts, (3) shelfbreak circulation, and (4) bathymetric and seabed variations.Because of the warming climate, the summertime ice extent on the Chukchi/Beaufort shelves and in the adjacent Canada Basin has decreased drastically over the last decade. As a result, the sea ice has become younger and more mobile [1]. A presumed primary acoustical consequence of this altered ice condition is reduction of transmission loss. Also, the increased ice mobility has led to stronger upwelling at the Chukchi and Beaufort shelf edge in conjunction with enhanced easterly winds [2-3]. This in turn significantly alters the hydrographic conditions of the water column, with strong ramifications for sound propagation.Underwater sound propagation in the Canada Basin and the Beaufort Sea can be efficient through the sound duct formed within the Pacific-water halocline layer located about 50-250 m below surface (see Figure 1). In the deep basin, the structure of this water-borne acoustic duct can be perturbed by the abundant subsurface eddies with diameters on the order of 20 km. It is estimated that the Canada Basin is filled with 100-200 of these eddies at any given time [4-6].