1Department of Physics, P.O. Box 64, 00014 University of Helsinki, Helsinki, Finland
2Helsinki University Centre of Environment, P.O. Box 65, 00014 University of Helsinki, Helsinki, Finland
3Department of Wind Energy, Technical University of Denmark, Frederiksborgvej 399, P.O. Box 49, Building 118, 4000 Roskilde, Denmark
4National Center for Atmospheric Research, Boulder, Colorado, USA
5Department of Applied Physics, University of Eastern Finland, 70211 Kuopio, Finland
6National Park Service, Air Resources Division, Lakewood, CO, USA
7Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
8NOAA/Geophysical Fluid Dynamics Laboratory, Princeton University Cooperative Institute for Climate Science, Princeton, NJ, USA
9Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington, USA
10University of Innsbruck, Institute for Meteorology and Geophysics (IMGI), Innrain 52, 6020 Innsbruck, Austria
Received: 03 Mar 2015 – Discussion started: 25 Mar 2015
Abstract. New particle formation (NPF) is an important atmospheric phenomenon. During an NPF event, particles first form by nucleation and then grow further in size. The growth step is crucial because it controls the number of particles that can become cloud condensation nuclei. Among various physical and chemical processes contributing to particle growth, condensation by organic vapors has been suggested as important. In order to better understand the influence of biogenic emissions on particle growth, we carried out modeling studies of NPF events during the BEACHON-ROCS (Bio–hydro–atmosphere interactions of Energy, Aerosol, Carbon, H2O, Organics & Nitrogen – Rocky Mountain Organic Carbon Study) campaign at Manitou Experimental Forest Observatory in Colorado, USA. The site is representative of the semi-arid western USA. With the latest Criegee intermediate reaction rates implemented in the chemistry scheme, the model underestimates sulfuric acid concentration by 50 %, suggesting either missing sources of atmospheric sulfuric acid or an overestimated sink term. The results emphasize the contribution from biogenic volatile organic compound emissions to particle growth by demonstrating the effects of the oxidation products of monoterpenes and 2-Methyl-3-buten-2-ol (MBO). Monoterpene oxidation products are shown to influence the nighttime particle loadings significantly, while their concentrations are insufficient to grow the particles during the day. The growth of ultrafine particles in the daytime appears to be closely related to the OH oxidation products of MBO.
Revised: 13 Jul 2015 – Accepted: 18 Jul 2015 – Published: 06 Aug 2015
Zhou, L., Gierens, R., Sogachev, A., Mogensen, D., Ortega, J., Smith, J. N., Harley, P. C., Prenni, A. J., Levin, E. J. T., Turnipseed, A., Rusanen, A., Smolander, S., Guenther, A. B., Kulmala, M., Karl, T., and Boy, M.: Contribution from biogenic organic compounds to particle growth during the 2010 BEACHON-ROCS campaign in a Colorado temperate needleleaf forest, Atmos. Chem. Phys., 15, 8643-8656, doi:10.5194/acp-15-8643-2015, 2015.