In situ calibration of observatory broadband echosounders

Abstract Today, numerous scientific echosounders are used as continuously monitoring systems in ocean observatories. These echosounders are usually calibrated in shallow water, either in laboratory tanks or at random ocean docks before deployments. If the systems are used for quantitative measuremen...

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Bibliographic Details
Published in:ICES Journal of Marine Science
Main Authors: Ona, Egil, Zhang, Guosong, Pedersen, Geir, Johnsen, Espen
Other Authors: Demer, David
Format: Article in Journal/Newspaper
Language:English
Published: Oxford University Press (OUP) 2020
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Online Access:http://dx.doi.org/10.1093/icesjms/fsaa177
http://academic.oup.com/icesjms/article-pdf/77/7-8/2954/35589386/fsaa177.pdf
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Summary:Abstract Today, numerous scientific echosounders are used as continuously monitoring systems in ocean observatories. These echosounders are usually calibrated in shallow water, either in laboratory tanks or at random ocean docks before deployments. If the systems are used for quantitative measurements by the observatories, they should be calibrated at the operating depths to consider the environmental effects on the calibration parameters. In this article, a simple in situ calibration method is presented, which was recently applied to one of the nodes of the Norwegian Lofoten-VesterĂ¥len ocean observatory, when the research vessel with dynamic positioning system suspended and moved the calibration sphere between the vessel and the transducer. The calibration results of a 70-kHz split-beam echosounder demonstrate that this method can be applied to the cabled observatories.