A new methodology for quantifying bubble flow rates in deep water using splitbeam echosounders: Examples from the Arctic offshore NW-Svalbard

Veloso, M., Greinert, Jens, Mienert, J. and De Batist, M. (2015) 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, 13 (6). pp. 267-287. DOI 10.1002/lom3.10024.

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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.

Document Type: Article
Additional Information: WOS:000356975300001
Keywords: GULF-OF-MEXICO; COAL OIL POINT; BLACK-SEA; SPATIAL HETEROGENEITY; METHANE EBULLITION; HYDROCARBON SEEPS; GAS EMISSIONS; FLUID-FLOW; QUANTIFICATION; CALIFORNIA
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems > DeepSea Monitoring
Refereed: Yes
DOI etc.: 10.1002/lom3.10024
ISSN: 1541-5856
Related URLs:
Projects: COST, PERGAMON
Contribution Number:
ProjectNumber
eprint_fieldopt_contribution_number_project_DSM6
Date Deposited: 16 Jul 2015 10:34
Last Modified: 15 Sep 2017 08:52
URI: http://eprints.uni-kiel.de/id/eprint/29252

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