Concurrent inversion of geo- and bio-acoustic parameters from transmission loss measurements in the Yellow Sea

Diachok, Orest; Wales, Stephen C.

doi:10.1121/1.1862093

Cited by 8 publications

(4 citation statements)

References 35 publications

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“…These lines are attributed to 15 cm sardines and schools of sardines respectively. Estimates of layer depths, which were derived by matching TL measurements with calculations that included an attenuating layer (Diachok and Wales, 2005b), are consistent with concurrent echo sounder measurements. Attribution of these lines to 15 cm sardines is based on concurrent trawls.…”

Section: A (Db/km) = [Tl(measured) -Tl(calculated)] / Rsupporting

confidence: 58%

Bio-Alpha off the West Coast

Diachok¹

2012

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LONG-TERM GOALSDevelop quantitative models of the effects of fish with swim bladders on attenuation (bio-alpha), transmission loss, and scintillation index in the ocean. OBJECTIVESConduct an experiment off the west coast to determine the effects of hake and sardines, the dominant species of fish with swim bladders off the west coast of the USA, on attenuation (bio-alpha), transmission loss (TL) and scintillation index (SI). Determine the effects of gas production and removal from swim bladders of hake, a physoclist, on the temporal evolution of resonance frequencies. Isolate the effects of hake from the effects of sardines and anchovies, which may be present in large numbers during the experiment. Determine bubble cloud effects of schools of sardines and hake. APPROACHBio-alpha measurements will be made along a track that traverses a mesoscale region, where the concentrations of the target species, hake and sardines are high. We will select the site of the bio-alpha measurements, based on biological scattering maps generated by Dr. Roger Gauss of NRL, and echo sounder and trawling measurements by Dr. Kelly Benoit-Bird of the Oregon State University (OSU) and Dr. Dezhang Chu of the Northwest Fisheries Science Center (NWFSC). The selected track will be relatively flat, approximately parallel to shore.We will conduct measurements of TL vs. range (0-8 km) and frequency (0.2-5 kHz), about 6 times during night, and about 6 times during day for 2 days. The transit speed will be nominally 3 knots. The depth of the source will be alternated between a near surface depth (TBD), and a near bottom depth (TBD). To minimize the uncertainty of geoacoustic effects on TL we will repeat TL measurements along the same (or if necessary, a nearby track) when fish are absent.We will make concurrent measurements of sound speed profiles with XBT's and depths of fish layers with an echo sounder from the source ship. The composition of the dominant species along this track will be provided by Dr. Kelly Benoit-Bird of the OSU and Dr. Dezhang Chu of the NWFSC.We will also conduct measurements of SI with the ship at an approximately fixed range (to the extent possible without DP), at about 5 km, for 1 hour periods during night and day. We will not conduct long term TL and SI measurements between a fixed source and fixed receivers, as originally planned,

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Section: A (Db/km) = [Tl(measured) -Tl(calculated)] / Rsupporting

confidence: 58%

Bio-Alpha off the West Coast

Diachok¹

2012

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“…This replacement effectively "spreads" a concentrated fish shoal across the water column while retaining the total number of fish. Previous studies have modeled attenuation from fish in a waveguide using this formulation [12,29].…”

Section: Methodsmentioning

confidence: 99%

The Effect of Attenuation from Fish Shoals on Long-Range, Wide-Area Acoustic Sensing in the Ocean

et al. 2019

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Acoustics is the primary means of long-range and wide-area sensing in the ocean due to the severe attenuation of electromagnetic waves in seawater. While it is known that densely packed fish groups can attenuate acoustic signals during long-range propagation in an ocean waveguide, previous experimental demonstrations have been restricted to single line transect measurements of either transmission or backscatter and have not directly investigated wide-area sensing and communication issues. Here we experimentally show with wide-area sensing over 360 • in the horizontal and ranges spanning many tens of kilometers that a single large fish shoal can significantly occlude acoustic sensing over entire sectors spanning more than 30 • with corresponding decreases in detection ranges by roughly an order of magnitude. Such blockages can comprise significant impediments to underwater acoustic remote sensing and surveillance of underwater vehicles, marine life and geophysical phenomena as well as underwater communication. This makes it important to understand the relevant mechanisms and accurately predict attenuation from fish in long-range underwater acoustic sensing and communication. To do so, we apply an analytical theory derived from first principles for acoustic propagation and scattering through inhomogeneities in an ocean waveguide to model propagation through fish shoals. In previous experiments, either the attenuation from fish in the shoal or the scattering cross sections of fish in the shoal were measured but not both, making it impossible to directly confirm a theoretical prediction on attenuation through the shoal. Here, both measurements have been made and they experimentally confirm the waveguide theory presented. We find experimentally and theoretically that attenuation can be significant when the sensing frequency is near the resonance frequency of the shoaling fish. Negligible attenuation was observed in previous low-frequency ocean acoustic waveguide remote sensing (OAWRS) experiments because the sensing frequency was sufficiently far from the swimbladder resonance peak of the shoaling fish or the packing densities of the fish shoals were not sufficiently high. We show that common heuristic approaches that employ free space scattering assumptions for attenuation from fish groups can lead to significant errors for applications involving long-range waveguide propagation and scattering.

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“…Other relevant research works were analyzed and reviewed by Furusawa et al (1992) [6]. Diachok (2005) conducted a study on estimating the number density from the attenuation of anchovy schools during the day and night at the mid-frequency range of 1-3 kHz in shallow water environments through transmission loss measurements [20]. Raveau and Feuillade (2015) recently studied sound extinction by fish schools on the basis of the forward scattering theory [21].…”

Section: Introductionmentioning

confidence: 99%

In Situ Measurement of Sound Attenuation by Fish Schools (Japanese Horse Mackerel, Trachurus japonicus) at Mid-Frequency Bands

Kim

Paeng

2021

Applied Sciences

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Acoustic waves are attenuated by fish schools as they propagate through the ocean. The attenuation by fish schools is not currently considered in fishery acoustics and sonar applications, especially at mid-frequency bands. In this study, fish school attenuation experiments were conducted with a number of individual fish in situ in a net cage at mid-frequency bands (3–7 kHz). The target fish species was the Japanese horse mackerel (Trachurus japonicus), which typically forms fish schools in the coastal ocean of northeastern Asia. The attenuated acoustic waves were measured for the cases of non-net, only net (0), 100, 200, 300, 400, and 500 individual horse mackerels in the net cage. Results showed that the acoustic signal attenuation increased with the number of horse mackerels. The mean and maximum attenuation coefficients were approximately 6.0–15.4 dB/m and 6.5–21.8 dB/m for all frequencies, respectively. The measured attenuation coefficients were compared with the ones from previous studies to propose new regression models with normalized extinction cross-sections of weight and length of fish. This study confirmed that the fish school attenuation could not be ignored and compensated at mid-frequencies in the ocean. These results would be useful for fishery acoustics, especially in the development of scientific echo-sounder, and naval applications of sonar operations and analysis.

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Concurrent inversion of geo- and bio-acoustic parameters from transmission loss measurements in the Yellow Sea

Cited by 8 publications

References 35 publications

Bio-Alpha off the West Coast

Bio-Alpha off the West Coast

The Effect of Attenuation from Fish Shoals on Long-Range, Wide-Area Acoustic Sensing in the Ocean

In Situ Measurement of Sound Attenuation by Fish Schools (Japanese Horse Mackerel, Trachurus japonicus) at Mid-Frequency Bands

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