High resolution population density imaging of random scatterers with the matched filtered scattered field variance

Andrews, Mark; Gong, Zheng; Ratilal, Purnima

doi:10.1121/1.3177271

Cited by 18 publications

(27 citation statements)

References 28 publications

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“…The water-column temperature and salinity were measured using Expendable Bathythermographs (XBTs) and Conductivity-Temperature-Depth (CTD) sensors. Other details about the measurement geometry and oceanographic properties of the environment are provided in Section II of [16] and also in [1,2,17,22,23,41,59,64].…”

Section: Gulf Of Maine 2006 Experiments Acoustic Data Collectionmentioning

confidence: 99%

Vocalization Source Level Distributions and Pulse Compression Gains of Diverse Baleen Whale Species in the Gulf of Maine

et al. 2016

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Abstract:The vocalization source level distributions and pulse compression gains are estimated for four distinct baleen whale species in the Gulf of Maine: fin, sei, minke and an unidentified baleen whale species. The vocalizations were received on a large-aperture densely-sampled coherent hydrophone array system useful for monitoring marine mammals over instantaneous wide areas via the passive ocean acoustic waveguide remote sensing technique. For each baleen whale species, between 125 and over 1400 measured vocalizations with significantly high Signal-to-Noise Ratios (SNR > 10 dB) after coherent beamforming and localized with high accuracies (<10% localization errors) over ranges spanning roughly 1 km-30 km are included in the analysis. The whale vocalization received pressure levels are corrected for broadband transmission losses modeled using a calibrated parabolic equation-based acoustic propagation model for a random range-dependent ocean waveguide. The whale vocalization source level distributions are characterized by the following means and standard deviations, in units of dB re 1 µPa at 1 m: 181.9 ± 5.2 for fin whale 20-Hz pulses, 173.5 ± 3.2 for sei whale downsweep chirps, 177.7 ± 5.4 for minke whale pulse trains and 169.6 ± 3.5 for the unidentified baleen whale species downsweep calls. The broadband vocalization equivalent pulse-compression gains are found to be 2.5 ± 1.1 for fin whale 20-Hz pulses, 24 ± 10 for the unidentified baleen whale species downsweep calls and 69 ± 23 for sei whale downsweep chirps. These pulse compression gains are found to be roughly proportional to the inter-pulse intervals of the vocalizations, which are 11 ± 5 s for fin whale 20-Hz pulses, 29 ± 18 for the unidentified baleen whale species downsweep calls and 52 ± 33 for sei whale downsweep chirps. The source level distributions and pulse compression gains are essential for determining signal-to-noise ratios and hence detection regions for baleen whale vocalizations received passively on underwater acoustic sensing systems, as well as for assessing communication ranges in baleen whales.

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Section: Gulf Of Maine 2006 Experiments Acoustic Data Collectionmentioning

confidence: 99%

Vocalization Source Level Distributions and Pulse Compression Gains of Diverse Baleen Whale Species in the Gulf of Maine

et al. 2016

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“…These scattered returns are collected by a towed receiver and charted in range and bearing, resulting in an instantaneous snapshot of the ocean over hundreds of square kilometers. The intensity of the scattered returns from fish shoals is proportional to the fish population density [3], [27], so that, by repeating transmissions at regular intervals, a population density image sequence is generated. A detailed technical description of the OAWRS system can be found in [20], [27], [32], [33].…”

Section: Application To Fish Population Density Imagesmentioning

confidence: 99%

Force estimation and prediction from time-varying density images

Jagannathan

Horn

Ratilal

et al. 2012

The Journal of the Acoustical Society of America

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Abstract-We present methods for estimating forces which drive motion observed in density image sequences. Using these forces, we also present methods for predicting velocity and density evolution. To do this, we formulate and apply a Minimum Energy Flow (MEF) method which is capable of estimating both incompressible and compressible flows from time-varying density images. Both the MEF and force-estimation techniques are applied to experimentally obtained density images, spanning spatial scales from micrometers to several kilometers. Using density image sequences describing cell splitting, for example, we show that cell division is driven by gradients in apparent pressure within a cell. Using density image sequences of fish shoals, we also quantify 1) intershoal dynamics such as coalescence of fish groups over tens of kilometers, 2) fish mass flow between different parts of a large shoal, and 3) the stresses acting on large fish shoals.

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“…The expected magnitude square of the scattered field, |Φ F | 2 , received at location r from N omni-directional targets randomly distributed with uniform probability in a vertical layer of thickness H centered at z = z 0 within a resolution footprint A R (ρ C ) centered at horizontal location ρ C can be determined from [23,30]:…”

Section: Detection Of Scattered Returns From Herring Shoals and The Smentioning

confidence: 99%

Feasibility of Acoustic Remote Sensing of Large Herring Shoals and Seafloor by Baleen Whales

Makris

2016

Remote Sensing

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Recent research has found a high spatial and temporal correlation between certain baleen whale vocalizations and peak herring spawning processes in the Gulf of Maine. These vocalizations are apparently related to feeding activities with suggested functions that include communication, prey manipulation, and echolocation. Here, the feasibility of the echolocation function is investigated. Physical limitations on the ability to detect large herring shoals and the seafloor by acoustic remote sensing are determined with ocean acoustic propagation, scattering, and statistical theories given baleen whale auditory parameters. Detection is found to be highly dependent on ambient noise conditions, herring shoal distributions, baleen whale time-frequency vocalization spectra, and geophysical parameters of the ocean waveguide. Detections of large herring shoals are found to be physically feasible in common Gulf of Maine herring spawning scenarios at up to 10 ± 6 km in range for humpback parameters and 1 ± 1 km for minke parameters but not for blue and fin parameters even at zero horizontal range. Detections of the seafloor are found to be feasible up to 2 ± 1 km for blue and humpback parameters and roughly 1 km for fin and minke parameters, suggesting that the whales share a common acoustic sensation of rudimentary features of the geophysical environment.

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High resolution population density imaging of random scatterers with the matched filtered scattered field variance

Cited by 18 publications

References 28 publications

Vocalization Source Level Distributions and Pulse Compression Gains of Diverse Baleen Whale Species in the Gulf of Maine

Vocalization Source Level Distributions and Pulse Compression Gains of Diverse Baleen Whale Species in the Gulf of Maine

Force estimation and prediction from time-varying density images

Feasibility of Acoustic Remote Sensing of Large Herring Shoals and Seafloor by Baleen Whales

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