Page 55 - Spring2020

Peter F. Worcester
Address:
Scripps Institution of Oceanography University of California, San Diego 9500 Gilman Drive, 0225 La Jolla, California 92093-0225 USA
Email:
pworcester@ucsd.edu
Matthew A. Dzieciuch
Address:
Scripps Institution of Oceanography University of California, San Diego 9500 Gilman Drive, 0225 La Jolla, California 92093-0225 USA
Email:
mdzieciuch@ucsd.edu
Hanne Sagen
Address:
Nansen Environmental and Remote Sensing Center Thormøhlensgate 47 N-5006 Bergen Norway
Email:
hanne.sagen@nersc.no
Ocean Acoustics in the Rapidly Changing Arctic
Multipurpose acoustic systems have special roles to play in providing observations year-round in ice-covered regions, complementing and supporting other observations.
Interest in Arctic acoustics began in the early years of the Cold War between the United States and the Soviet Union with the development of nuclear-powered sub- marines capable of operating for extended periods under the ice (Hutt, 2012). In 1958, the first operational nuclear submarine, the USS Nautilus (SSN 571), reached the North Pole during a submerged transit from the Bering Strait to northeast of Greenland. Beginning in the late 1950s, extensive research on Arctic acoustics was done from manned ice islands and seasonal ice camps to obtain the knowledge needed to support submarine operations and conduct antisubmarine warfare. How- ever, military interest in Arctic acoustics waned with the end of the Cold War in the early 1990s.
As military interest was waning, there was increasing interest in the dramatic changes that the Arctic Ocean is undergoing in response to increasing atmospheric concentrations of carbon dioxide and other greenhouse gases (Jeffries et al., 2013). Surface air temperature in the Arctic has warmed at more than twice the global rate over the past 50 years (AMAP, 2017) while sea ice extent and thickness have declined dramatically (Stroeve and Notz, 2018). Moreover, ocean stratification is changing as warmer waters have entered the Arctic from the North Atlantic and North Pacific Oceans.
The ice cover presents a difficult challenge for an Arctic Ocean observing system designed to monitor the changes that are underway (Figure 1). Profiling floats, gliders, and autonomous underwater vehicles that measure ocean temperature,
Figure 1. Sea ice in Fram Strait in August 2012. Photo by Peter Worcester, Scripps Institution of Oceanography, La Jolla, CA.
©2020 Acoustical Society of America. All rights reserved.
https://doi.org/10.1121/AT.2020.16.1.55
volume 16, issue 1 | Spring 2020 | Acoustics Today | 55