Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea
Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s −1 to derive the...
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2017
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ftdoajarticles:oai:doaj.org/article:929a84c8539c4f259a18fe5e7f2c5461 2023-05-15T15:01:50+02:00 Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea I. Leifer D. Chernykh N. Shakhova I. Semiletov 2017-06-01T00:00:00Z https://doi.org/10.5194/tc-11-1333-2017 https://doaj.org/article/929a84c8539c4f259a18fe5e7f2c5461 EN eng Copernicus Publications http://www.the-cryosphere.net/11/1333/2017/tc-11-1333-2017.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-11-1333-2017 1994-0416 1994-0424 https://doaj.org/article/929a84c8539c4f259a18fe5e7f2c5461 The Cryosphere, Vol 11, Pp 1333-1350 (2017) Environmental sciences GE1-350 Geology QE1-996.5 article 2017 ftdoajarticles https://doi.org/10.5194/tc-11-1333-2017 2022-12-30T21:17:07Z Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s −1 to derive the in situ calibration curve ( Q ( σ )). These nonlinear curves related flux ( Q ) to sonar return ( σ ) for a multibeam echosounder (MBES) and a single-beam echosounder (SBES) for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering – precluding the use of a theoretical approach to derive Q ( σ ) from the product of the bubble σ ( r ) and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function (Ψ( σ )) with respect to Q found Ψ( σ ) for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. Ψ( σ ) for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core. Ψ( σ ) was bimodal for all but the weakest plumes. Q ( σ ) was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes ( Q m ) were 5.56, 42.73, and 4.88 mmol s −1 for MBES data with good to reasonable agreement (4–37 %) between the SBES and MBES systems. The seepage flux occurrence probability distribution function (Ψ( Q )) was bimodal, with weak Ψ( Q ) in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost. Article in Journal/Newspaper Arctic laptev Laptev Sea permafrost The Cryosphere Directory of Open Access Journals: DOAJ Articles Arctic Laptev Sea The Cryosphere 11 3 1333 1350 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 I. Leifer D. Chernykh N. Shakhova I. Semiletov Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s −1 to derive the in situ calibration curve ( Q ( σ )). These nonlinear curves related flux ( Q ) to sonar return ( σ ) for a multibeam echosounder (MBES) and a single-beam echosounder (SBES) for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering – precluding the use of a theoretical approach to derive Q ( σ ) from the product of the bubble σ ( r ) and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function (Ψ( σ )) with respect to Q found Ψ( σ ) for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. Ψ( σ ) for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core. Ψ( σ ) was bimodal for all but the weakest plumes. Q ( σ ) was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes ( Q m ) were 5.56, 42.73, and 4.88 mmol s −1 for MBES data with good to reasonable agreement (4–37 %) between the SBES and MBES systems. The seepage flux occurrence probability distribution function (Ψ( Q )) was bimodal, with weak Ψ( Q ) in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost. |
format |
Article in Journal/Newspaper |
author |
I. Leifer D. Chernykh N. Shakhova I. Semiletov |
author_facet |
I. Leifer D. Chernykh N. Shakhova I. Semiletov |
author_sort |
I. Leifer |
title |
Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea |
title_short |
Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea |
title_full |
Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea |
title_fullStr |
Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea |
title_full_unstemmed |
Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea |
title_sort |
sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer laptev sea |
publisher |
Copernicus Publications |
publishDate |
2017 |
url |
https://doi.org/10.5194/tc-11-1333-2017 https://doaj.org/article/929a84c8539c4f259a18fe5e7f2c5461 |
geographic |
Arctic Laptev Sea |
geographic_facet |
Arctic Laptev Sea |
genre |
Arctic laptev Laptev Sea permafrost The Cryosphere |
genre_facet |
Arctic laptev Laptev Sea permafrost The Cryosphere |
op_source |
The Cryosphere, Vol 11, Pp 1333-1350 (2017) |
op_relation |
http://www.the-cryosphere.net/11/1333/2017/tc-11-1333-2017.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-11-1333-2017 1994-0416 1994-0424 https://doaj.org/article/929a84c8539c4f259a18fe5e7f2c5461 |
op_doi |
https://doi.org/10.5194/tc-11-1333-2017 |
container_title |
The Cryosphere |
container_volume |
11 |
container_issue |
3 |
container_start_page |
1333 |
op_container_end_page |
1350 |
_version_ |
1766333844748763136 |