Atmos. Chem. Phys. Discuss., 10, 24435-24497, 2010
www.atmos-chem-phys-discuss.net/10/24435/2010/
doi:10.5194/acpd-10-24435-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Importance of secondary sources in the atmospheric budgets of formic and acetic acids
F. Paulot1, D. Wunch1, J. D. Crounse2, G. C. Toon3, D. B. Millet4, P. F. DeCarlo5, C. Vigouroux6, N. M. Deutscher7, G. González Abad8, J. Notholt9, T. Warneke9, J. W. Hannigan10, C. Warneke11,12, J. A. de Gouw11,12, E. J. Dunlea12, M. De Mazière6, D. W. T. Griffith7, P. Bernath8, J. L. Jimenez12,13, and P. O. Wennberg1
1Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California, USA
2Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
4University of Minnesota, Department of Soil, Water and Climate, St. Paul, Minnesota, USA
5Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
6Belgisch Instituut voor Ruimte-Aëronomie, Brussels, Belgium
7School of Chemistry, University of Wollongong, Wollongong, Australia
8Department of Chemistry, University of York, York, UK
9Institute of Environmental Physics, Bremen, Germany
10National Center for Atmospheric Research, Boulder, Colorado, USA
11Aeronomy Laboratory, NOAA, Boulder, Colorado, USA
12Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
13Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado, USA

Abstract. We present a detailed budget of formic and acetic acids, two of the most abundant trace gases in the atmosphere. Our bottom-up estimate of the global source of formic and acetic acids are ~1200 and ~1400 Gmol/yr, dominated by photochemical oxidation of biogenic volatile organic compounds, in particular isoprene. Their sinks are dominated by wet and dry deposition. We use the GEOS-Chem chemical transport model to evaluate this budget against an extensive suite of measurements from ground, ship and satellite-based Fourier transform spectrometers, as well as from several aircraft campaigns over North America. The model captures the seasonality of formic and acetic acids well but generally underestimates their concentration, particularly in the Northern midlatitudes. We infer that the source of both carboxylic acids may be up to 50% greater than our estimate and report evidence for a long-lived missing secondary source of carboxylic acids that may be associated with the aging of organic aerosols. Vertical profiles of formic acid in the upper troposphere support a negative temperature dependence of the reaction between formic acid and the hydroxyl radical as suggested by several theoretical studies.

Citation: Paulot, F., Wunch, D., Crounse, J. D., Toon, G. C., Millet, D. B., DeCarlo, P. F., Vigouroux, C., Deutscher, N. M., González Abad, G., Notholt, J., Warneke, T., Hannigan, J. W., Warneke, C., de Gouw, J. A., Dunlea, E. J., De Mazière, M., Griffith, D. W. T., Bernath, P., Jimenez, J. L., and Wennberg, P. O.: Importance of secondary sources in the atmospheric budgets of formic and acetic acids, Atmos. Chem. Phys. Discuss., 10, 24435-24497, doi:10.5194/acpd-10-24435-2010, 2010.
 
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