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Air‐sea exchange of methanol and acetone during HiWinGS: Estimation of air phase, water phase gas transfer velocities
Author(s) -
Yang Mingxi,
Blomquist Byron W.,
Nightingale Philip D.
Publication year - 2014
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010227
Subject(s) - atmosphere (unit) , methanol , eddy covariance , mass transfer , chemistry , seawater , trace gas , flux (metallurgy) , analytical chemistry (journal) , atmospheric sciences , meteorology , environmental chemistry , geology , chromatography , oceanography , physics , ecology , organic chemistry , ecosystem , biology
The air‐sea fluxes of methanol and acetone were measured concurrently using a proton‐transfer‐reaction mass spectrometer (PTR‐MS) with the eddy covariance (EC) technique during the High Wind Gas Exchange Study (HiWinGS) in 2013. The seawater concentrations of these compounds were also measured twice daily with the same PTR‐MS coupled to a membrane inlet. Dissolved concentrations near the surface ranged from 7 to 28 n M for methanol and from 3 to 9 n M for acetone. Both gases were consistently transported from the atmosphere to the ocean as a result of their low sea surface saturations. The largest influxes were observed in regions of high atmospheric concentrations and strong winds (up to 25 m s −1 ). Comparison of the total air‐sea transfer velocity of these two gases ( K a ), along with the in situ sensible heat transfer rate, allows us to constrain the individual gas transfer velocity in the air phase ( k a ) and water phase ( k w ). Among existing parameterizations, the scaling of k a from the COARE model is the most consistent with our observations. The k w we estimated is comparable to the tangential (shear driven) transfer velocity previously determined from measurements of dimethyl sulfide. Lastly, we estimate the wet deposition of methanol and acetone in our study region and evaluate the lifetimes of these compounds in the surface ocean and lower atmosphere with respect to total (dry plus wet) atmospheric deposition.