Modelling atmospheric OH-reactivity in a boreal forest ecosystem
1Division of Atmospheric Sciences, Department of Physics, P.O. Box 48, University of Helsinki, 00014, Finland
2Helsinki University Centre for Environment, P.O. Box 27, University of Helsinki, 00014, Finland
3Wind Energy Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, Building 118, Box 49, 4000, Roskilde, Denmark
4Max Planck Institute of Chemistry, J. Becher Weg 27, 55128 Mainz, Germany
5Indian Institute of Science Education and Research (IISER) Mohali, MGSIPAP Complex, Sector 26, Chandigarh 160019, India
6National Center for Atmospheric Research, Boulder, CO 80307, USA
Abstract. 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.