Coherence of low‐frequency acoustic signals in the deep ocean

1974 ◽  
Vol 56 (4) ◽  
pp. 1122-1125 ◽  
Author(s):  
J. D. Shaffer ◽  
R. M. Fitzgerald ◽  
A. N. Guthrie
Keyword(s):  
Low Frequency ◽  
Deep Ocean ◽  
Acoustic Signals

scholarly journals Bottom interaction of low-frequency acoustic signals at small grazing angles in the deep ocean

1981 ◽  
Author(s):  
George V. Frisk ◽  
James A. Doutt ◽  
Earl E. Hays
Keyword(s):  
Low Frequency ◽  
Deep Ocean ◽  
Acoustic Signals ◽  
Grazing Angles

scholarly journals Bottom interaction of low‐frequency acoustic signals at small grazing angles in the deep ocean

1981 ◽  
Vol 69 (1) ◽  
pp. 84-94 ◽  
Author(s):  
George V. Frisk ◽  
James A. Doutt ◽  
Earl E. Hays
Keyword(s):  
Low Frequency ◽  
Deep Ocean ◽  
Acoustic Signals ◽  
Grazing Angles

Fish Attraction with Pulsed Low-Frequency Sound

1968 ◽  
Vol 25 (7) ◽  
pp. 1441-1452 ◽  
Author(s):  
Joseph D. Richard
Keyword(s):  
Acoustic Stimulus ◽  
Low Frequency ◽  
Reef Fishes ◽  
Test Site ◽  
Acoustic Signals ◽  
Commercial Fisheries ◽  
Test Results ◽  
Potential Applications ◽  
Predatory Fishes ◽  
Underwater Television

A series of tests were conducted to determine the effectiveness of pulsed low-frequency acoustic signals for attracting fishes. The acoustic signals were contrived to simulate the hydrodynamically generated disturbances normally associated with active predation. Underwater television was used to observe fish arrivals during both control and test periods. Demersal predatory fishes were successfully attracted although they habituated rapidly to the acoustic stimulus. Members of the families Serranidae, Lutjanidae, and Pomadasyidae were particularly well represented among the fishes attracted. Sharks were also attracted in considerable numbers. Herbivorous reef fishes, although common around the test site, were not attracted. Possible relationships between the test results and the hearing capabilities of fishes are discussed. It is concluded that acoustic attraction techniques have potential applications in certain existing commercial fisheries.

scholarly journals Climate Process Team on Internal Wave–Driven Ocean Mixing

2017 ◽  
Vol 98 (11) ◽  
pp. 2429-2454 ◽  
Author(s):  
Jennifer A. MacKinnon ◽  
Zhongxiang Zhao ◽  
Caitlin B. Whalen ◽  
Amy F. Waterhouse ◽  
David S. Trossman ◽  
...  
Keyword(s):  
Internal Wave ◽  
Turbulent Mixing ◽  
Low Frequency ◽  
Internal Tide ◽  
Deep Ocean ◽  
Global Ocean ◽  
Primary Role ◽  
Inverse Models ◽  
Lee Waves ◽  
Mixing Rates

Abstract Diapycnal mixing plays a primary role in the thermodynamic balance of the ocean and, consequently, in oceanic heat and carbon uptake and storage. Though observed mixing rates are on average consistent with values required by inverse models, recent attention has focused on the dramatic spatial variability, spanning several orders of magnitude, of mixing rates in both the upper and deep ocean. Away from ocean boundaries, the spatiotemporal patterns of mixing are largely driven by the geography of generation, propagation, and dissipation of internal waves, which supply much of the power for turbulent mixing. Over the last 5 years and under the auspices of U.S. Climate Variability and Predictability Program (CLIVAR), a National Science Foundation (NSF)- and National Oceanic and Atmospheric Administration (NOAA)-supported Climate Process Team has been engaged in developing, implementing, and testing dynamics-based parameterizations for internal wave–driven turbulent mixing in global ocean models. The work has primarily focused on turbulence 1) near sites of internal tide generation, 2) in the upper ocean related to wind-generated near inertial motions, 3) due to internal lee waves generated by low-frequency mesoscale flows over topography, and 4) at ocean margins. Here, we review recent progress, describe the tools developed, and discuss future directions.

Propagation of Low‐Frequency CW Sound Signals in the Deep Ocean

1965 ◽  
Vol 38 (6) ◽  
pp. 1060-1061 ◽  
Author(s):  
Albert N. Guthrie ◽  
John D. Shaffer
Keyword(s):  
Low Frequency ◽  
Deep Ocean

scholarly journals Climate models can correctly simulate the continuum of global-average temperature variability

2019 ◽  
Vol 116 (18) ◽  
pp. 8728-8733 ◽  
Author(s):  
Feng Zhu ◽  
Julien Emile-Geay ◽  
Nicholas P. McKay ◽  
Gregory J. Hakim ◽  
Deborah Khider ◽  
...  
Keyword(s):  
Climate Models ◽  
Initial Conditions ◽  
Low Frequency ◽  
Deep Ocean ◽  
Critical Element ◽  
Average Temperature ◽  
Global Mean Temperature ◽  
Low Frequency Variability ◽  
Climate Forcings ◽  
Global Mean

Climate records exhibit scaling behavior with large exponents, resulting in larger fluctuations at longer timescales. It is unclear whether climate models are capable of simulating these fluctuations, which draws into question their ability to simulate such variability in the coming decades and centuries. Using the latest simulations and data syntheses, we find agreement for spectra derived from observations and models on timescales ranging from interannual to multimillennial. Our results confirm the existence of a scaling break between orbital and annual peaks, occurring around millennial periodicities. That both simple and comprehensive ocean–atmosphere models can reproduce these features suggests that long-range persistence is a consequence of the oceanic integration of both gradual and abrupt climate forcings. This result implies that Holocene low-frequency variability is partly a consequence of the climate system’s integrated memory of orbital forcing. We conclude that climate models appear to contain the essential physics to correctly simulate the spectral continuum of global-mean temperature; however, regional discrepancies remain unresolved. A critical element of successfully simulating suborbital climate variability involves, we hypothesize, initial conditions of the deep ocean state that are consistent with observations of the recent past.

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