Atmospheric Chemistry and Physics (Sep 2011)

Modelling atmospheric OH-reactivity in a boreal forest ecosystem

  • D. Mogensen,
  • S. Smolander,
  • A. Sogachev,
  • L. Zhou,
  • V. Sinha,
  • A. Guenther,
  • J. Williams,
  • T. Nieminen,
  • M. K. Kajos,
  • J. Rinne,
  • M. Kulmala,
  • M. Boy

DOI
https://doi.org/10.5194/acp-11-9709-2011
Journal volume & issue
Vol. 11, no. 18
pp. 9709 – 9719

Abstract

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We have modelled the total atmospheric OH-reactivity in a boreal forest and investigated the individual contributions from gas phase inorganic species, isoprene, monoterpenes, and methane along with other important VOCs. Daily and seasonal variation in OH-reactivity for the year 2008 was examined as well as the vertical OH-reactivity profile. We have used SOSA; a one dimensional vertical chemistry-transport model (Boy et al., 2011a) together with measurements from Hyytiälä, SMEAR II station, Southern Finland, conducted in August 2008. Model simulations only account for ~30–50% of the total measured OH sink, and in our opinion, the reason for missing OH-reactivity is due to unmeasured unknown BVOCs, and limitations in our knowledge of atmospheric chemistry including uncertainties in rate constants. Furthermore, we found that the OH-reactivity correlates with both organic and inorganic compounds and increases during summer. The summertime canopy level OH-reactivity peaks during night and the vertical OH-reactivity decreases with height.