Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 4 4 2004 10.5194/acpd-4-4641-2004 http://www.atmos-chem-phys-discuss.net/4/4641/2004/ http://www.atmos-chem-phys-discuss.net/4/4641/2004/acpd-4-4641-2004.html http://www.atmos-chem-phys-discuss.net/4/4641/2004/acpd-4-4641-2004.pdf 4641 4664 2004-08-20 Measurements of organic gases during aerosol formation events in the boreal forest atmosphere during QUEST K. Sellegri karine.sellegri@nuigalway.ie M. Hanke B. Umann F. Arnold M. Kulmala Atmospheric Physic Division, Max Planck Institute for Nuclear Physics, Heidelberg, Germany Department of Physical Sciences, University of Helsinki, Finland Biogenic VOCs are important in the growth and possibly also in the formation of atmospheric aerosol particles. In this work, we present 10 min-time resolution measurements of organic trace gases at Hyytiälä, Finland during March 2002. The measurements were part of the project QUEST (Quantification of Aerosol Nucleation in the European Boundary Layer) and took place during a two-week period when nucleation events occurred with various intensities nearly every day. Using a ground-based Chemical Ionization Mass Spectrometer (CIMS) instrument, the following trace gases were detected: acetone, TMA, DMA, mass 68 amu (candidate=isoprene), monoterpenes, Methyl Vinyl Ketone (MVK) and Methacrolein (MaCR), cis-3-hexenyl acetate and MonoTerpene Oxidation Products (MTOP). For all of them except for the amines, we present daily variations during different classes of event days, and non-event days. Isoprene, monoterpenes, MVK+MaCR, cis-3-hexenyl acetate and MTOP are found to show significant correlations with the condensational sink (CS), which indicates that a fraction of these compounds are participating to the growth of the nucleated particles and generally secondary organic aerosol formation. Moreover, the terpene oxidation products (TOP) (MVK, MaCR and MTOP) show a higher ratio to the CS on event days compared to non-event days, indicating that their abundance relative to the surface of aerosol available is higher on nucleation days.