Accession Number:

AD1024347

Title:

Alaska North Shore Ocean Acoustics Study

Descriptive Note:

Technical Report,01 Oct 2014,30 Sep 2015

Corporate Author:

Woods Hole Oceanographic Institution Woods Hole United States

Personal Author(s):

Report Date:

2015-09-30

Pagination or Media Count:

7.0

Abstract:

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 circulationupwelling 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 ChukchiBeaufort 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.

Subject Categories:

  • Acoustics
  • Physical and Dynamic Oceanography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE