ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-8-2821-2008 Airborne measurements of nucleation mode particles II: boreal forest nucleation events O'Dowd C. D. 1 Yoon Y. J. 1 2 Junkerman W. 3 Aalto P. 4 Kulmala M. 4 Lihavainen H. 5 Viisanen Y. 5 Department of Physics and Centre for Climate and Air Pollution Studies, Environmental Change Institute, National University of Ireland, University Road, Galway, Ireland Korea Polar Research Institute, KORDI, 7–50, Songdo-dong, Incheon 406–840, Korea Fraunhofer Institute for Atmospheric Environmental Research, Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany Department of Physical Sciences, P.O. Box 64 (Gustaf Hällströmin katu 2) PL 64, 00014 University of Helsinki, Helsinki, Finland Finnish Meteorological Institute, Erik Palménin aukio, P.O. Box 503 00101, Helsinki, Finland 13 02 2008 8 1 2821 2848 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/8/2821/2008/acpd-8-2821-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/8/2821/2008/acpd-8-2821-2008.pdf

Airborne measurements of nucleation mode aerosol concentrations during nucleation events over the boreal forest of southern Finland are reported. Three case studies are analysis in an attempt to characterise the spatial scales over which these events occur and to identify the source region for particle production. For the cases presented, there is no evidence of nucleation mode particles in the Free Troposphere. Nucleation mode particles are first detected in the surface layer as the nocturnal inversion breaks up and develops into the current-day's new boundary layer. In terms of spatial variability, significant variability in the concentration of nucleation mode particles was observed and was attributed to changes in the topography which comprised a mix of forest canopy and frozen lakes. Measurements over the Gulf of Bothnia indicated no nucleation mode over the sea and confirm that the scale of the events is associated with the boreal forest scale and that the new particles are produced directly above the forest canopy.

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