Cristin-resultat-ID: 1262964
Sist endret: 9. september 2015, 14:41
Faglig foredrag

Comparative studies and field measurements of the acoustic absorption coefficient in seawater

  • Dezhang Chu
  • Gavin Macaulay og
  • Egil Ona


Navn på arrangementet: ICES Symposium on “Marine Ecosystem Acoustics - observing the ocean interior in support of integrated management”
Sted: Nantes
Dato fra: 25. mai 2015
Dato til: 28. mai 2015


Arrangørnavn: ICES

Om resultatet

Faglig foredrag
Publiseringsår: 2015

Beskrivelse Beskrivelse


Comparative studies and field measurements of the acoustic absorption coefficient in seawater


The absorption coefficient of seawater is an important component to the sonar equation underlying fisheries and zooplankton acoustic investigations. The equations currently considered most accurate and widely used for calculating the coefficient are the three decades-old work of Francois and Garrison (1982, J. Acoust. Soc. Am. 72: 896- 907, and 72: 1879-1890). However, there is evidence to suggest that these equations are inadequate for the higher frequency applications that have become increasingly important in ecosystem-based acoustic surveys and management. Comparative studies among the different formulas will be presented. In situ measurements of acoustic absorption were conducted onboard the R/V G. O. SARS in the Norwegian fjords from 2011 to 2014. It was found that the absorption coefficient at 333 kHz was about 18.5 dB/km more than that given by Francois and Garrison's work, which could lead to an uncertainty in biomass estimates of about 50% more at a range of 100 m. In addition, inaccurate absorption coefficients will also introduce a depth-dependent bias on frequency response and impair acoustic echo characterization and species identification/classification that strongly rely on relative frequency response.


Dezhang Chu

  • Tilknyttet:

Gavin John Macaulay

Bidragsyterens navn vises på dette resultatet som Gavin Macaulay
  • Tilknyttet:
    ved Økosystemakustikk ved Havforskningsinstituttet

Egil Ona

  • Tilknyttet:
    ved Institutt for biovitenskap ved Universitetet i Bergen
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