Estimation of bubble-mediated air-sea gas exchange from concurrent DMS and CO2 transfer velocities at intermediate-high wind speeds

TitleEstimation of bubble-mediated air-sea gas exchange from concurrent DMS and CO2 transfer velocities at intermediate-high wind speeds
Publication TypeJournal Article
Year of Publication2017
AuthorsBell T.G, Landwehr S., Miller S.D, de Bruyn W.J, Callaghan AH, Scanlon B., Ward B., Yang M.X, Saltzman E.S
JournalAtmospheric Chemistry and Physics
Volume17
Pagination9019-9033
Date Published2017/07
Type of ArticleArticle
ISBN Number1680-7316
Accession NumberWOS:000406389100001
Keywordsbreaking; covariance; dimethylsulfide dms; eddy-correlation; flux measurements; ocean; parameterization; temperature; water; wave
Abstract

Simultaneous air-sea fluxes and concentration differences of dimethylsulfide (DMS) and carbon dioxide (CO2) were measured during a summertime North Atlantic cruise in 2011. This data set reveals significant differences between the gas transfer velocities of these two gases (Delta k(w)) over a range of wind speeds up to 21ms(-1). These differences occur at and above the approximate wind speed threshold when waves begin breaking. Whitecap fraction (a proxy for bubbles) was also measured and has a positive relationship with Delta k(w), consistent with enhanced bubble-mediated transfer of the less soluble CO2 relative to that of the more soluble DMS. However, the correlation of Delta k(w) with whitecap fraction is no stronger than with wind speed. Models used to estimate bubble-mediated transfer from in situ whitecap fraction underpredict the observations, particularly at intermediate wind speeds. Examining the differences between gas transfer velocities of gases with different solubilities is a useful way to detect the impact of bubble-mediated exchange. More simultaneous gas transfer measurements of different solubility gases across a wide range of oceanic conditions are needed to understand the factors controlling the magnitude and scaling of bubble-mediated gas exchange.

DOI10.5194/acp-17-9019-2017
Short TitleAtmos. Chem. Phys.
Student Publication: 
No
Research Topics: 
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