Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 7 1 2007 10.5194/acp-7-201-2007 http://www.atmos-chem-phys.net/7/201/2007/ http://www.atmos-chem-phys.net/7/201/2007/acp-7-201-2007.html http://www.atmos-chem-phys.net/7/201/2007/acp-7-201-2007.pdf 201 210 2007-01-15 Identification and classification of the formation of intermediate ions measured in boreal forest A. Hirsikko anne.hirsikko@helsinki.fi T. Bergman L. Laakso M. Dal Maso I. Riipinen U. Hõrrak M. Kulmala Department of Physical Sciences, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland Institute of Environmental Physics, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia We have measured the size distributions of air ions (0.42–7.5 nm in diameter) with the Balanced Scanning Mobility Analyzer in boreal forest, in Southern Finland since spring 2003. The size range covers the size range of cluster ions (approximately 0.42–1.6 nm) and naturally charged nanometre aerosol particles (1.6–7.5 nm) or intermediate air ions. Based on the measurements from April 2003 to March 2006 we studied the characteristics of charged aerosol particle formation by classifying each day either as a particle formation event, undefined or non-event day. The principal of the classification, as well as the statistical description of the charged aerosol particle formation events are given. We found in total 270 (26% of the analysed days) and 226 (22% of the analysed days) particle formation days for negative and positive intermediate ions, respectively. For negatively charged particles we classified 411 (40% of the analysed days) undefined and 348 (34% of the analysed days) non-event days whereas for positively charged particles 343 (33% of the analysed days) undefined and 460 (45% of the analysed days) non-event days. The results were compared with the ordinary classification based on the Differential Mobility Particle Sizer (DMPS) measurements carried out at the same place. The above-presented values differed slightly from that found from the DMPS data, with a lower particle diameter of 3 nm. In addition, we have found the rain-induced intermediate ion bursts frequently. The rain effect was detected on 163 days by means of negative ions and on 105 days by positive ones. Another interesting phenomenon among the charged aerosol particles was the appearance and existence of intermediate ions during the snowfall. We observed this phenomenon 24 times with negatively charged particles and 21 times with positively charged ones during winter months (October–April). These intermediate air ions were seen during the snowfall and may be caused by ice crystals, although the origin of these intermediate ions is unclear at the moment. Aalto, P., Hämeri, K., Becker, E., Weber, R., Salm, J., Mäkelä, J. M., Hoell, C., O'Dowd, C. O., Karlsson, H., Hansson, H.-C., Väkevä, M., Koponen, I. K, Buzorius, G., and Kulmala, M.: Physical characterization of aerosol particles during nucleation events, Tellus, 53B, 344–358, 2001. Boy, M., Kulmala, M., Ruuskanen, T. M., Pihlatie, M., Reissell, A., Aalto, P. P., Keronen, P., Dal Maso, M., Hellen, H., Hakola, H., Jansson, R., Hanke, M., and Arnold, F.: Sulphuric acid closure and contribution to nucleation mode particle growth, Atmos. Chem. Phys., 5, 863–878, 2005. Dal Maso, M., Kulmala, M., Riipinen, I., Wagner, R., Hussein, T., Aalto, P. P., and Lehtinen, K. E. J.: Formation and growth of fresh atmospheric aerosols: eight years of aerosol size distribution data from SMEAR II, Hyytiälä, Finland, Boreal Environ. Res., 10, 323–336, 2005. Froyd, K. D. and Lovejoy, E. R.: Experimental Thermodynamics of Cluster Ions Composed of H₂SO₄ and H₂O. 1. Positive Ions, J. Phys. Chem. A, 107, 9800–9811, 2003a. Froyd, K. D. and Lovejoy, E. R.: Experimental Thermodynamics of Cluster Ions Composed of H₂SO₄ and H₂O. 2. Measurements and ab Initio Structures of Negative Ions, J. Phys. Chem. A, 107, 9812–9824, 2003b. Gamero-Castaño, M. and Fernández de la Mora, J.: Direct measurement of ion evaporation kinetics from electrified liquid surfaces, J. Chem. Phys., 113, 815–832, 2000a. Gamero-Castaño, M. and Fernández de la Mora, J.: Mechanisms of electrospray ionisation of singly and multiply charged salt clusters, Analytica Chimica Acta, 406, 67–91, 2000b. Hari, P. and Kulmala, M.: Station for Measuring Ecosystem–Atmosphere Relations (SMEAR II), Boreal Environ. Res., 10, 315–322, 2005. Hirsikko, A., Laakso, L., Hörrak, U., Aalto, P. P., Kerminen, V.-M., and Kulmala, M.: Annual and size dependent variation of growth rates and ion concentrations in boreal forest, Boreal Environ. Res., 10, 357–369, 2005. Hõrrak, U., Iber, H., Luts, A., Salm, J., and Tammet, H.: Mobility spectrum of air ions at Tahkuse Observatory, J. Geophys. Res., 99, 10 697–10 700, 1994. Hõrrak, U., Salm, J., and Tammet, H.: Diurnal variation in the concentration of air ions of different mobility classes in a rural area, J. Geophys. Res., 108, 4653, doi:10.1029/2002JD003240, 2003. Hõrrak, U., Tammet, H., Aalto, P. P., Vana, M., Hirsikko, A., Laakso, L., and Kulmala, M.: Formation of charged nanometer aerosol particles associated with rainfall, Proceedings of European Aerosol Conference 2005, p. 606, 2005. Hõrrak, U., Tammet, H., Aalto, P. P., Vana, M., Hirsikko, A., Laakso, L., and Kulmala, M.: Formation of Charged Nanometer Aerosol Particles Associated with Rainfall: Atmospheric Measurements and Lab Experiment, Proceedings of BACCI, NECC and FCoE activities 2005, Report Series in Aerosol Sciences, 81, 180–185, 2006. Iribarne, J. V. and Thomson, B. A.: On the evaporation of small ions from charged droplets, J. Chem. Phys., 64, 2287–2294, 1976. Israel, H.: Atmospheric electricity, Israel Program for Scientific Translations, 1, Jerusalem, 1970. Kaufman, Y. J., Tanré, D., and Boucher, O.: A satellite view of aerosols in the climate system, Nature, 419, 215–223, 2002. Kulmala, M., Hämeri, K., Aalto, P. P., Mäkelä, J. M., Pirjola, L., Nilsson, E. D., Buzorius, G., Rannik, Ü., Dal Maso, M., Seidl, W., Hoffman, T., Janson, R., Hansson, H.-C., Viisanen, Y., Laaksonen, A., and O'Dowd, C. D.: Overview of the international project on biogenic aerosol formation in the boreal forest (BIOFOR), Tellus, 53B, 324–343, 2001. Kulmala, M., Laakso, L., Lehtinen, K. E. J., Riipinen, I., Dal Maso, M., Anttila, T., Kerminen, V.-M., Hörrak, U., Vana, M., and Tammet, H.: Initial steps of aerosol growth, Atmos. Chem. Phys., 4, 2553–2560, 2004a. Kulmala, M., Vehkamäki, H., Petäjä, T., Dal Maso, M., Lauri, A., Kerminen, V.-M., Birmili, W., and McMurry, P. H.: Formation and growth rates of ultrafine atmospheric particles: A review of observations, J. Aerosol Sci., 35, 143–176, 2004b. Laakso, L., Grönholm, T., Rannik, Ü., Kosmale, M., Fiedler, V., Vehkamäki, H., and Kulmala, M.: Ultrafine particle scavenging coefficients calculated from 6 years field measurements, Atmos. Environ., 37(25), 3605–3613, 2003a. Laakso, L., Kulmala, M., and Lehtinen K. E. J.: Effect of condensation rate enhancement factor on 3-nm (diameter) particle formation in binary ion-induced and homogeneous nucleation, J. Geophys. Res., 108, 4574, doi:10.1029/2003JD003432, 2003b. Laakso, L., Anttila, T., Lehtinen, K. E. J., Aalto, P. P., Kulmala, M., Hõrrak, U., Paatero, J., Hanke, M., and Arnold, F.: Kinetic nucleation and ions in boreal particle formation events, Atmos. Chem. Phys., 4, 2353–2366, 2004. Laakso, L., Gagné, S., Petäjä, T., Hirsikko, A., Aalto, P., Kulmala, M., and Kerminen, V.-M.: Detecting charging state of ultra-fine particles: instrumental development and ambient measurements, Atmos. Chem. Phys. Discuss., 6, 6401–6429, 2006. Lovejoy, E. R., Curtius, J., and Froyd, K. D.: Atmospheric ion-induced nucleation of sulphuric acid and water, J. Geophys. Res., 109, D08204, doi:10.1029/2003JD004460, 2004. Nadykto, A. and Yu, F.: Uptake of neutral polar vapour molecules by charged particles: Enhancement due to dipole-charge interaction, J. Geophys. Res., 108(D23), 4717, doi:10.1029/2003JD003664, 2003. Pope, C. A., Burnett, R. T., Thun, M. J., Calle, E. E., Krewski, D., Ito, K., and Thurston, G. D.: Lung Cancer, Cardiopulmonary Mortality, and Long-term Exposure to Fine Particulate Air Pollution, J. Amer. Med. Assoc., 287, 1132–1141, 2002. Tammet, H.: Size and mobility of nanometer particles, clusters and ions, J. Aerosol Sci., 26, 459–475, 1995. Tammet, H.: Reduction of air ion mobility to standard conditions, J. Geophys. Res., 103, 13 933–13 937, 1998. Tammet, H.: Balanced Scanning Mobility Analyzer, in: Proc. 16th International Conference on Nucleation & Atmospheric Aerosols in Kyoto, 2004. Tammet, H.: Continuous scanning of the mobility and size distribution of charged clusters and nanometer particles in atmospheric air and the Balanced Scanning Mobility Analyzer BSMA, Atmos. Res., 523–535, 2006. Vesala, T., Haataja, J., Aalto, P., Altimir, N., Buzorius, G., Garam, E., Hämeri, K., Ilvesniemi, H., Jokinen, V., Keronen, P., Lahti, T., Markkanen, T., Mäkelä, J. M., Nikinmaa, E., Palmroth, S., Palva, L., Pohja, T., Pumpanen, J., Rannik, Ü., Siivola, E., Ylitalo, H., Hari, P., and Kulmala, M.: Long-term field measurements of atmosphere-surface interactions in boreal forest combining forest ecology, micrometeorology, aerosol physics and atmospheric chemistry, Trends in Heat, Mass and Momentum Transfer, 4, 17–35, 1998. Wilhelm, S., Eichkorn, S., Wiedner, D., Pirjola, L., and Arnold, F.: Ion-induced aerosol formation: new insights from laboratory measurements of mixed cluster ions HSO₄\= (H₂SO$_4)_a$(H₂O)$_w $and H$^+$(H₂SO$_4)_a$(H₂O)$_w$, Atmos. Environ., 38, 1735–1744, 2004. Yu, F. and Turco, R. P.: Ultrafine aerosol formation via ion-mediated nucleation, Geophys. Res. Lett., 27(6), 883–886, 2000.