Atmos. Chem. Phys. Discuss., 13, 8101-8152, 2013
www.atmos-chem-phys-discuss.net/13/8101/2013/
doi:10.5194/acpd-13-8101-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Vertical fluxes and atmospheric cycling of methanol, acetaldehyde, and acetone in a coastal environment
M. Yang1, R. Beale1, T. Smyth1, and B. Blomquist2
1Plymouth Marine Laboratory, Prospect Place, Plymouth, Devon, UK
2Department of Oceanography, University of Hawaii, Honolulu, HI, USA

Abstract. We present here vertical fluxes of methanol, acetaldehyde, and acetone measured directly with eddy covariance (EC) during March to July 2012 near the southwest coast of the UK. The performance of the proton-transfer reaction mass spectrometer (PTR-MS) for flux measurement is characterized, with additional considerations given to the homogeneity and stationarity assumptions required by EC. Concentrations and fluxes of these compounds vary significantly with time of day and wind direction. Higher values of acetaldehyde and acetone are usually observed in the daytime and from the direction of a forested park, most likely due to light-driven emissions from terrestrial plants. Methanol concentration and flux do not demonstrate clear diel variability, suggesting sources in addition to plants. We estimate air–sea exchange and photochemical rates of these compounds, which are compared to measured vertical fluxes. For acetaldehyde, the mean (1σ) concentration of 0.13 (0.02) ppb at night may be maintained by oceanic emission, while photochemical destruction outpaces production during the day. Air-sea exchange and photochemistry are probably net sinks of methanol and acetone in this region. Their nighttime concentrations of 0.46 (0.20) and 0.39 (0.08) ppb appear to be affected more by terrestrial emissions and long distance transport, respectively.

Citation: Yang, M., Beale, R., Smyth, T., and Blomquist, B.: Vertical fluxes and atmospheric cycling of methanol, acetaldehyde, and acetone in a coastal environment, Atmos. Chem. Phys. Discuss., 13, 8101-8152, doi:10.5194/acpd-13-8101-2013, 2013.
 
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