scholarly journals Low‐frequency transmission loss modeling in the Arctic using measured mode attenuation coefficients

1987 ◽  
Vol 82 (S1) ◽  
pp. S31-S31
Author(s):  
T. C. Yang
Keyword(s):  
Transmission Loss ◽  
Low Frequency ◽  
The Arctic ◽  
Attenuation Coefficients ◽  
Loss Modeling

scholarly journals Characteristics of Low-Frequency Acoustic Wave Propagation in Ice-Covered Shallow Water Environment

2021 ◽  
Vol 11 (17) ◽  
pp. 7815
Author(s):  
Shande Li ◽  
Shuai Yuan ◽  
Shaowei Liu ◽  
Jian Wen ◽  
Qibai Huang ◽  
...  
Keyword(s):  
Parabolic Equation ◽  
Target Detection ◽  
Acoustic Field ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Low Frequency ◽  
Sound Field ◽  
The Arctic ◽  
Long Distance ◽  
Propagation Law

Mastering the sound propagation law of low-frequency signals in the Arctic is a major frontier basic research demand to improve the level of detection, communication, and navigation technology. It is of practical significance for long-distance sound propagation and underwater target detection in the Arctic Ocean. Therefore, how to establish an effective model to study the characteristics of the acoustic field in the Arctic area has always been a hot topic in polar acoustic research. Aimed at solving this problem, a mathematical polar acoustic field model with an elastic seafloor is developed based on a range-dependent elastic parabolic equation theory. Moreover, this method is applied to study the characteristics of polar sound propagation for the first attempt. The validity and effectiveness of the method and model are verified by the elastic normal mode method. Simultaneously, the propagation characteristics of low-frequency signals are studied in a polar sound field from three aspects, which are seafloor parameters, sea depth, and ice thickness. The results show that the elastic parabolic equation method can be well utilized to the Arctic low-frequency acoustic field. The analysis of the influence factors of the polar sound field reveals the laws of sound transmission loss of low-frequency signals, which is of great significance to provide information prediction for underwater submarine target detection and target recognition.

scholarly journals Low-frequency bursts of horizontally polarized waves in the Arctic sea-ice cover

2011 ◽  
Vol 57 (202) ◽  
pp. 231-237 ◽  
Author(s):  
David Marsan ◽  
Jérôme Weiss ◽  
Jean-Philippe Métaxian ◽  
Jacques Grangeon ◽  
Pierre-François Roux ◽  
...  
Keyword(s):  
Sea Ice ◽  
Regional Scale ◽  
Low Frequency ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Strong Activity ◽  
Temporal Sampling ◽  
Polarized Waves ◽  
Arctic Sea

AbstractWe report the detection of bursts of low-frequency waves, typically f = 0.025 Hz, on horizontal channels of broadband seismometers deployed on the Arctic sea-ice cover during the DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies) experiment in spring 2007. These bursts have amplitudes well above the ambient ice swell and a lower frequency content. Their typical duration is of the order of minutes. They occur at irregular times, with periods of relative quietness alternating with periods of strong activity. A significant correlation between the rate of burst occurrences and the ice-cover deformation at the ∼400 km scale centered on the seismic network suggests that these bursts are caused by remote, episodic deformation involving shearing across regional-scale leads. This observation opens the possibility of complementing satellite measurements of ice-cover deformation, by providing a much more precise temporal sampling, hence a better characterization of the processes involved during these deformation events.

scholarly journals Empirical Mode Reduction in a Model of Extratropical Low-Frequency Variability

2006 ◽  
Vol 63 (7) ◽  
pp. 1859-1877 ◽  
Author(s):  
D. Kondrashov ◽  
S. Kravtsov ◽  
M. Ghil
Keyword(s):  
Numerical Study ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
The Arctic ◽  
Reduced Model ◽  
The North ◽  
Low Frequency Variability ◽  
Intraseasonal Oscillations ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

Abstract This paper constructs and analyzes a reduced nonlinear stochastic model of extratropical low-frequency variability. To do so, it applies multilevel quadratic regression to the output of a long simulation of a global baroclinic, quasigeostrophic, three-level (QG3) model with topography; the model's phase space has a dimension of O(104). The reduced model has 45 variables and captures well the non-Gaussian features of the QG3 model's probability density function (PDF). In particular, the reduced model's PDF shares with the QG3 model its four anomalously persistent flow patterns, which correspond to opposite phases of the Arctic Oscillation and the North Atlantic Oscillation, as well as the Markov chain of transitions between these regimes. In addition, multichannel singular spectrum analysis identifies intraseasonal oscillations with a period of 35–37 days and of 20 days in the data generated by both the QG3 model and its low-dimensional analog. An analytical and numerical study of the reduced model starts with the fixed points and oscillatory eigenmodes of the model's deterministic part and uses systematically an increasing noise parameter to connect these with the behavior of the full, stochastically forced model version. The results of this study point to the origin of the QG3 model's multiple regimes and intraseasonal oscillations and identify the connections between the two types of behavior.

scholarly journals Long range transmission loss of broadband seismic pulses in the Arctic under ice-free conditions

2010 ◽  
Vol 128 (4) ◽  
pp. EL181-EL187 ◽  
Author(s):  
Aaron Thode ◽  
Katherine H. Kim ◽  
Charles R. Greene ◽  
Ethan Roth
Keyword(s):  
Long Range ◽  
Transmission Loss ◽  
The Arctic
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