Sound absorption based on ocean measurements. Part II: Boric acid contribution and equation for total absorption

François, R. E.; Garrison, G. R.

doi:10.1121/1.388673

Cited by 511 publications

(266 citation statements)

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“…Regarding sound absorption throughout the water column, the α coefficient (see Francois and Garrison 1982) was computed according to the local seawater properties at the surface which were fed into the acquisition system every half an hour. The necessary water medium environmental parameters were obtained from the On board Data Acquisition System (ODAS), which logs these data at 1-s intervals.…”

Section: Acquisitionmentioning

confidence: 99%

Seafloor change detection using multibeam echosounder backscatter: case study on the Belgian part of the North Sea

et al. 2017

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Section: Acquisitionmentioning

confidence: 99%

Seafloor change detection using multibeam echosounder backscatter: case study on the Belgian part of the North Sea

et al. 2017

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“…The noise level (E r ) of all four beams was determined from the minimum values of RSSI (Received Signal Strength Indicator) counts obtained in the remotest depth cell, when the sea surface was outside the ADCP range. Sound velocity c and sound absorption coefficient  were considered variable with depth and time and calculated according to the UNESCO formula introduced by Fofonoff and Millard (1983) and computed after Francois and Garrison (1982).…”

Section: Other Environmental Parametersmentioning

confidence: 99%

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Cisewski

Strass

2016

Progress in Oceanography

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The success of any efforts to determine the effects of climate change on marine ecosystems depends on understanding in the first instance the natural variations, which contemporarily occur on the interannual and shorter time scales. Here we present results on the environmental controls of zooplankton distribution patterns and behaviour in the eastern Weddell Sea, Southern Ocean. Zooplankton abundance and vertical migration are derived from the mean volume backscattering strength (MVBS) and the vertical velocity measured by moored acoustic Doppler current profilers (ADCPs), which were deployed simultaneously at 64°S, 66.5°S and 69°S along the Greenwich Meridian from February, 2005, until March, 2008 While these time series span a period of full three years they resolve hourly changes.A highly persistent behavioural pattern found at all three mooring locations is the synchronous diel vertical migration (DVM) of two distinct groups of zooplankton that migrate between a deep residence depth during daytime and a shallow depth during nighttime. The DVM was closely coupled to the astronomical daylight cycles. However, while the DVM was symmetric around local noon, the annual modulation of the DVM was clearly asymmetric around winter solstice or summer solstice, respectively, at all three mooring sites. DVM at our observation sites persisted throughout winter, even at the highest latitude exposed to the polar night. Since the magnitude as well as the relative rate of change of illumination is minimal at this time, we propose that the ultimate causes of DVM separated from the light-mediated proximal cue that coordinates it. In all three years, a marked change in the migration behaviour occurred in late spring (late October/early November), when DVM ceased. The complete suspension of DVM after early November is possibly caused by the combination of two factors: (1) increased availability of food in the surface mixed layer provided by the phytoplankton spring bloom, and (2) vanishing diurnal enhancement of the threat from visually oriented predators when the illumination is quasi-continuous during the polar and subpolar summer. 3Zooplankton abundance in the water column, estimated as the mean MVBS in the depth range 50 -300 m, was highest end of summer and lowest mid to end winter on the average annual cycle. However, zooplankton abundance varied several-fold between years and between locations. Based on satellite and in situ data of chlorophyll and sea ice as well as on hydrographic measurements, the interannual and spatial variations of zooplankton mean abundance can be explained by differences in the magnitude of the phytoplankton spring bloom, which develops during the seasonal sea ice retreat. Whereas the vernal ice melt appears necessary to stimulate the blooming of phytoplankton, it is not the determinator of the blooms magnitude, its areal extent and duration. A possible explanation for the limitation of the phytoplankton bloom in some years is top-down control. We hypothesize that the phytoplankton spring ...

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“…The absorption coefficient was calculated using an emprically-derived formula (Francois & Garrison 1982). The values for α T and k L assuming a sand bottom (Erbe 2002) and sea states 0 or 5, as well as the equation to calculate H based on a water depth of 100m are given in Marsh & Shulkin (1962).…”

Section: Active Space Estimationmentioning

confidence: 99%

Diversity in sound pressure levels and estimated active space of resident killer whale vocalizations

2006

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Please use second address for correspondence. pulsed calls and 24 whistles produced by free-ranging resident killer whales by triangulating the angles-of-arrival of sounds on two beamforming arrays towed in series. Levels in the 1-20 kHz band ranged from 131-168 dB re 1μPa @1m, with differences in the means of different sound classes (whistles: 140.2 ± 4.1 dB; variable calls: 146.6 ± 6.6 dB; stereotyped calls: 152.6 ± 5.9 dB), and among stereotyped call types. Repertoire diversity carried through to estimates of active space, with "long-range" stereotyped calls all containing overlapping, independently-modulated high-frequency components (mean estimated active space of 10-16km in sea state zero) and "short-range" sounds (5-9 km) included all stereotyped calls without a high-frequency component, whistles, and variable calls. Short-range sounds are reported to be more common during social and resting behaviors, while long-range stereotyped calls predominate in dispersed travel and foraging behaviors. These results suggest that variability in sound pressure levels may reflect diverse social and ecological functions of the acoustic repertoire of killer whales.

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Sound absorption based on ocean measurements. Part II: Boric acid contribution and equation for total absorption

Cited by 511 publications

References 0 publications

Seafloor change detection using multibeam echosounder backscatter: case study on the Belgian part of the North Sea

Seafloor change detection using multibeam echosounder backscatter: case study on the Belgian part of the North Sea

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Diversity in sound pressure levels and estimated active space of resident killer whale vocalizations

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