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Ocean Noise

Christian Che-Castaldo, Stephanie Jenouvrier, Casey Youngflesh, Kevin T Shoemaker, Grant Humphries, Philip McDowall, Laura Landrum, Marika M Holland, Yun Li, Rubao Ji, Heather J Lynch
Colonially-breeding seabirds have long served as indicator species for the health of the oceans on which they depend. Abundance and breeding data are repeatedly collected at fixed study sites in the hopes that changes in abundance and productivity may be useful for adaptive management of marine resources, but their suitability for this purpose is often unknown. To address this, we fit a Bayesian population dynamics model that includes process and observation error to all known Adélie penguin abundance data (1982-2015) in the Antarctic, covering >95% of their population globally...
October 10, 2017: Nature Communications
William D Halliday, Stephen J Insley, R Casey Hilliard, Tyler de Jong, Matthew K Pine
As the Arctic warms and sea ice decreases, increased shipping will lead to higher ambient noise levels in the Arctic Ocean. Arctic marine mammals are vulnerable to increased noise because they use sound to survive and likely evolved in a relatively quiet soundscape. We model vessel noise propagation in the proposed western Canadian Arctic shipping corridor in order to examine impacts on marine mammals and marine protected areas (MPAs). Our model predicts that loud vessels are audible underwater when >100km away, could affect marine mammal behaviour when within 2km for icebreakers vessels, and as far as 52km for tankers...
September 15, 2017: Marine Pollution Bulletin
Philip Judge
A laboratory experiment is suggested in which conditions similar to those in the plume ejecta from Enceladus and, perhaps, Europa are established. With the use of infrared spectroscopy and polarimetry, the experiment might identify possible biomarkers in differential measurements of water from the open ocean, hydrothermal vents, and abiotic water samples. Should the experiment succeed, large telescopes could be used to acquire sensitive infrared spectra of the plumes of Enceladus and Europa, as the satellites transit the bright planetary disks...
September 2017: Astrobiology
Kiwamu Nishida
The ambient seismic wave field, also known as ambient noise, is excited by oceanic gravity waves primarily. This can be categorized as seismic hum (1-20 mHz), primary microseisms (0.02-0.1 Hz), and secondary microseisms (0.1-1 Hz). Below 20 mHz, pressure fluctuations of ocean infragravity waves reach the abyssal floor. Topographic coupling between seismic waves and ocean infragravity waves at the abyssal floor can explain the observed shear traction sources. Below 5 mHz, atmospheric disturbances may also contribute to this excitation...
2017: Proceedings of the Japan Academy. Series B, Physical and Biological Sciences
Sébastien Angelliaume, Xavier Ceamanos, Françoise Viallefont-Robinet, Rémi Baqué, Philippe Déliot, Véronique Miegebielle
Remote sensing techniques are commonly used by Oil and Gas companies to monitor hydrocarbon on the ocean surface. The interest lies not only in exploration but also in the monitoring of the maritime environment. Occurrence of natural seeps on the sea surface is a key indicator of the presence of mature source rock in the subsurface. These natural seeps, as well as the oil slicks, are commonly detected using radar sensors but the addition of optical imagery can deliver extra information such as thickness and composition of the detected oil, which is critical for both exploration purposes and efficient cleanup operations...
August 2, 2017: Sensors
Sophie L Nedelec, Suzanne C Mills, Andrew N Radford, Ricardo Beldade, Stephen D Simpson, Brendan Nedelec, Isabelle M Côté
Human-made noise is contributing increasingly to ocean soundscapes. Its physical, physiological and behavioural effects on marine organisms are potentially widespread, but our understanding remains largely limited to intraspecific impacts. Here, we examine how motorboats affect an interspecific cleaning mutualism critical for coral reef fish health, abundance and diversity. We conducted in situ observations of cleaning interactions between bluestreak cleaner wrasses (Labroides dimidiatus) and their fish clients before, during and after repeated, standardised approaches with motorboats...
August 1, 2017: Scientific Reports
Keunhwa Lee, Woojae Seong, Seongil Kim
This paper proposes a roll-angle estimation method for the triplet towed array using the oceanic ambient noise recorded in the mid-frequency range of 1 to 10 kHz. Here, the dominance of oceanic surface-generated noises such as wind-driven and shipping noises is expected. The ratio between the approximated phase parts of the noise-coherence function regarding the triplet hydrophones is used for the roll estimation. Advantage of this technique is that explicit input regarding the oceanic environment is not required, especially for an ocean with an azimuthally uniform noise field or dominant noise sources at the end-fire direction of the horizontal array...
July 2017: Journal of the Acoustical Society of America
G Bazile Kinda, Florent Le Courtois, Yann Stéphan
The management of underwater noise within the European Union's waters is a significant component (Descriptor 11) of the Marine Strategy Framework Directive (MSFD). The indicator related to continuous noise, is the noise levels in two one-third octave bands centered at 63Hz and 125Hz. This paper presents an analysis of underwater noise in the Celtic Sea, a heavy shipping area which also hosts the seasonal Ushant thermal front. In addition to the MSFD recommended frequency bands, the analysis was extended to lower and upper frequency bands...
July 26, 2017: Marine Pollution Bulletin
Ibrahim Sadiek, Qiang Shi, Douglas W R Wallace, Gernot Friedrichs
Methyl iodide is a toxic halocarbon with diverse industrial and agricultural applications, and it is an important ocean-derived trace gas that contributes to the iodine burden of the atmosphere. Quantitative analysis of CH3I is mostly based on gas chromatography coupled with mass spectrometry or electron capture detection (GC-MS/ECD) as of yet, which often limits the ability to conduct in situ high-frequency monitoring studies. This work presents an alternative detection scheme based on mid-infrared continuous wave cavity ringdown spectroscopy (mid-IR cw-CRDS)...
August 4, 2017: Analytical Chemistry
Li-Wei Lin, Shu-Chuan Weng, Hua-Shan Wu, Lu-Jen Tsai, Ya-Ling Lin, Shu-Hui Yeh
BACKGROUND: The aging of society is a global trend, and care of older adults with dementia is an urgent challenge. As dementia progresses, patients exhibit negative emotions, memory disorders, sleep disorders, and agitated behavior. Agitated behavior is one of the most difficult problems for family caregivers and healthcare providers to handle when caring for older adults with dementia. PURPOSE: The aim of this study was to investigate the effectiveness of white noise in improving agitated behavior, mental status, and activities of daily living in older adults with dementia...
July 13, 2017: Journal of Nursing Research: JNR
Zhishan Zhao, Anbang Zhao, Juan Hui, Baochun Hou, Reza Sotudeh, Fang Niu
The most classical detector of active sonar and radar is the matched filter (MF), which is the optimal processor under ideal conditions. Aiming at the problem of active sonar detection, we propose a frequency-domain adaptive matched filter (FDAMF) with the use of a frequency-domain adaptive line enhancer (ALE). The FDAMF is an improved MF. In the simulations in this paper, the signal to noise ratio (SNR) gain of the FDAMF is about 18.6 dB higher than that of the classical MF when the input SNR is -10 dB. In order to improve the performance of the FDAMF with a low input SNR, we propose a pre-processing method, which is called frequency-domain time reversal convolution and interference suppression (TRC-IS)...
July 4, 2017: Sensors
Ilaria Spiga, Nicholas Aldred, Gary S Caldwell
Anthropogenic noise is a significant pollutant of the world's oceans, affecting behavioural and physiological traits in a range of species, including anti-predator behaviours. Using the open field test, we investigated the effects of recordings of piling and drilling noise on the anti-predator behaviour of captive juvenile European seabass in response to a visual stimulus (a predatory mimic). The impulsive nature of piling noise triggered a reflexive startle response, which contrasted the behaviour elicited by the continuous drilling noise...
June 26, 2017: Marine Pollution Bulletin
Francesco Caruso, Giuseppe Alonge, Giorgio Bellia, Emilio De Domenico, Rosario Grammauta, Giuseppina Larosa, Salvatore Mazzola, Giorgio Riccobene, Gianni Pavan, Elena Papale, Carmelo Pellegrino, Sara Pulvirenti, Virginia Sciacca, Francesco Simeone, Fabrizio Speziale, Salvatore Viola, Giuseppa Buscaino
Dolphins emit short ultrasonic pulses (clicks) to acquire information about the surrounding environment, prey and habitat features. We investigated Delphinidae activity over multiple temporal scales through the detection of their echolocation clicks, using long-term Passive Acoustic Monitoring (PAM). The Istituto Nazionale di Fisica Nucleare operates multidisciplinary seafloor observatories in a deep area of the Central Mediterranean Sea. The Ocean noise Detection Experiment collected data offshore the Gulf of Catania from January 2005 to November 2006, allowing the study of temporal patterns of dolphin activity in this deep pelagic zone for the first time...
June 28, 2017: Scientific Reports
Zeng-Zhen Hu, Arun Kumar, Jieshun Zhu, Bohua Huang, Yu-Heng Tseng, Xiaochun Wang
The possible factors associated with the shortening of lead time between ocean warm water volume (WWV) variability along the equatorial Pacific and El Niño-Southern Oscillation (ENSO) variability after 2000 are documented. It is shown that the shortening of lead time is due to frequency increases of both WWV and ENSO. During 1979-99 the dominant frequencies were 1.5-3.5 years for both the Niño3.4 and WWV indices. In contrast, during 2000-16, both indices had a relatively flatter spectrum and were closer to a white noise process with a relative maximum at 1...
June 27, 2017: Scientific Reports
Fulong Jing, Shuhong Jiao, Changbo Hou, Weijian Si, Yu Wang
For targets with complex motion, such as ships fluctuating with oceanic waves and high maneuvering airplanes, azimuth echo signals can be modeled as multicomponent quadratic frequency modulation (QFM) signals after migration compensation and phase adjustment. For the QFM signal model, the chirp rate (CR) and the quadratic chirp rate (QCR) are two important physical quantities, which need to be estimated. For multicomponent QFM signals, the cross terms create a challenge for detection, which needs to be addressed...
June 21, 2017: Sensors
Arthur B Baggeroer
A direct version for the stochastic Cramér-Rao bound (CRB) for parameters of Gaussian signals with additive Gaussian noise is introduced. The formulation applies to passive and active radars/sonars/seismics/structures with vector observations from multiple sources. These sensors include pressure, vector velocity, and/or acceleration sensors for ocean and structural acoustics, seismometers, polarized receivers for electromagnetics, and vector current meters for oceanography. The observations may contain partially coherent signals such as multipath...
May 2017: Journal of the Acoustical Society of America
Jonathan M Lilly
A method is derived for the quantitative analysis of signals that are composed of superpositions of isolated, time-localized 'events'. Here, these events are taken to be well represented as rescaled and phase-rotated versions of generalized Morse wavelets, a broad family of continuous analytic functions. Analysing a signal composed of replicates of such a function using another Morse wavelet allows one to directly estimate the properties of events from the values of the wavelet transform at its own maxima. The distribution of events in general power-law noise is determined in order to establish significance based on an expected false detection rate...
April 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
Chris H Harrison
The cross-spectral density of ocean ambient noise is usually estimated from the product of the complex hydrophone signals, each of which already corresponds to the summed responses of sources from all angles. The true coherence is the integral over all angles of the angle-dependent product. The influence of this distinction on necessary time integration in geoacoustic inversion and passive fathometry is explored, and a meaningful separation of the cross-spectral density matrix into Toeplitz and Hankel parts is proposed...
April 2017: Journal of the Acoustical Society of America
Sangeet Lamichhaney, Angela P Fuentes-Pardo, Nima Rafati, Nils Ryman, Gregory R McCracken, Christina Bourne, Rabindra Singh, Daniel E Ruzzante, Leif Andersson
Atlantic herring is an excellent species for studying the genetic basis of adaptation in geographically distant populations because of its characteristically large population sizes and low genetic drift. In this study we compared whole-genome resequencing data of Atlantic herring populations from both sides of the Atlantic Ocean. An important finding was the very low degree of genetic differentiation among geographically distant populations (fixation index = 0.026), suggesting lack of reproductive isolation across the ocean...
April 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
Graham A Warner, Stan E Dosso, David E Hannay
This paper estimates bowhead whale locations and uncertainties using nonlinear Bayesian inversion of the time-difference-of-arrival (TDOA) of low-frequency whale calls recorded on onmi-directional asynchronous recorders in the shallow waters of the northeastern Chukchi Sea, Alaska. A Y-shaped cluster of seven autonomous ocean-bottom hydrophones, separated by 0.5-9.2 km, was deployed for several months over which time their clocks drifted out of synchronization. Hundreds of recorded whale calls are manually associated between recorders...
March 2017: Journal of the Acoustical Society of America
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