A new methodology for quantifying bubble flow rates in deep water using splitbeam echosounders: Examples from the Arctic offshore NW-Svalbard
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https://hdl.handle.net/10037/24967Date
2015-05-08Type
Journal articleTidsskriftartikkel
Peer reviewed
Abstract
Quantifying marine methane fluxes of free gas (bubbles) from the seafloor into the water column is of importance for climate related studies, for example, in the Arctic, reliable methodologies are also of interest for studying
man-made gas and oil leakage systems at hydrocarbon production sites. Hydroacoustic surveys with singlebeam
and nowadays also multibeam systems have been proven to be a successful approach to detect bubble release
from the seabed. A number of publications used singlebeam echosounder data to indirectly quantify free gas fluxes
via empirical correlations between gas fluxes observed at the seafloor and the hydroacoustic response. Others utilize the hydroacoustic information in an inverse modeling approach to derive bubble fluxes. Here, we present an
advanced methodology using data from splitbeam echosounder systems for analyzing gas release water depth
(> 100m). We introduce a new MATLAB-based software for processing and interactively editing data and we present how bubble-size distribution, bubble rising speed and the model used for calculating the backscatter response
of single bubbles influence the final gas flow rate calculations. As a result, we highlight the need for further investigations on how large, wobbly bubbles, bubble clouds, and multi-scattering influence target strength. The results
emphasize that detailed studies of bubble-size distributions and rising speeds need to be performed in parallel to
hydroacoustic surveys to achieve realistic mediated methane flow rate and flux quantifications.
Publisher
WileyCitation
Veloso M, Greinert J, Mienert J, De Batist. A new methodology for quantifying bubble flow rates in deep water using splitbeam echosounders: Examples from the Arctic offshore NW-Svalbard. Limnology and Oceanography : Methods. 2015;13(6):267-287Metadata
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