Nighttime isoprene trends at an urban forested site during the 1999 Southern Oxidant Study

C. A. Stroud, J. M. Roberts, E. J. Williams, D. Hereid, W. M. Angevine, F. C. Fehsenfeld, A. Wisthaler, A. Hansel, M. Martinez-Harder, H. Harder, William Henry Brune, G. Hoenninger, J. Stutz, A. B. White

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Abstract

Measurements of isoprene and its oxidation products, methacrolein, methyl vinyl ketone and peroxymethacrylic nitric anhydride, were conducted between 13 June and 14 July 1999, at the Cornelia Fort Airpark during the Nashville intensive of the Southern Oxidant Study. Trends in isoprene and its oxidation products showed marked variability from night-to-night. The reaction between isoprene and the nitrate radical was shown to be important to the chemical budget of isoprene and often caused rapid decay of isoprene mixing ratios in the evening. Trends in methacrolein, methyl vinyl ketone, and peroxymethacrylic nitric anhydride were steady during the evening isoprene decay period, consistent with their slow reaction rate with the nitrate radical. For cases when isoprene sustained and even increased in mixing ratio throughout the night, the observed isoprene oxidation rates via the hydroxyl radical, ozone, and the nitrate radical were all small. Sustained isoprene mixing ratios within the nocturnal boundary layer give a unique opportunity to capture hydroxyl radical photochemistry at sunrise as isoprene was observed to rapidly convert to its first stage oxidation products before vertical mixing significantly redistributed chemical species. The observed nighttime isoprene variability at urban, forested sites is related to a complex coupling between nighttime boundary layer dynamics and chemistry.

Original languageEnglish (US)
JournalJournal of Geophysical Research Atmospheres
Volume107
Issue number16
Publication statusPublished - Jan 1 2002

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All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology

Cite this

Stroud, C. A., Roberts, J. M., Williams, E. J., Hereid, D., Angevine, W. M., Fehsenfeld, F. C., ... White, A. B. (2002). Nighttime isoprene trends at an urban forested site during the 1999 Southern Oxidant Study. Journal of Geophysical Research Atmospheres, 107(16).