ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-8-18155-2008 Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere Costabile F. 1 2 Birmili W. 1 Klose S. 1 Tuch T. 1 3 Wehner B. 1 Wiedensohler A. 1 Franck U. 3 König K. 1 Sonntag A. 1 Leibniz Institute for Tropospheric Research, Leipzig, Germany C.N.R. – IIA, Via Salaria Km 29, 3, 00016 Monterotondo Scalo (Roma), Italy Helmholtz Center for Environmental Research, Leipzig, Germany 16 10 2008 8 5 18155 18217 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/8/18155/2008/acpd-8-18155-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/8/18155/2008/acpd-8-18155-2008.pdf

Due to the presence of diffusive anthropogenic sources in urban areas, the spatio-temporal variability of fine (diameter <1 μm) and ultrafine (<0.1 μm) aerosol particles has been a challenging issue in particle exposure assessment as well as atmospheric research in general. We examined number size distributions of atmospheric aerosol particles (size range 3–800 nm) that were measured simultaneously at a maximum of eight observation sites in and around a city in Central Europe (Leipzig, Germany). Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites). A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting principal components, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300–800 nm), considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90–250 nm), considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30–200 nm) linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5–20 nm) linked to urban traffic emissions; nucleation modes (3–20 nm) linked to photochemically induced particle formation; an aged nucleation mode (10–50 nm). A number of additional components were identified to represent only local sources at a single site each, or infrequent phenomena. In summary, the analysis of size distributions of high time and size resolution yielded a surprising wealth of statistical aerosol components occurring in the urban atmosphere over one single city. Meanwhile, satisfactory physical explanations could be found for the components with the greatest temporal persistence and spatial coverage. Therefore a paradigm on the behaviour of sub-μm urban aerosol particles is proposed, with recommendations how to efficiently monitor individual sub-fractions across an entire city.

 References Andronache, C.: Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer, J. Geophys. Res., 109, D16S07, doi:10.1029/2003JD004050, 2004. Birmili, W., Stratmann, F., and Wiedensohler, A.: Design of a DMA-Based Size Spectrometer for a Large Particle Size Range and Stable Operation, J. Aerosol Sci., 30, 549–553, 1999. Birmili, W. and Wiedensohler, A.: New particle formation in the continental boundary layer: Meteorological and gas phase parameter influence, Geophys. Res. Lett., 27, 3325–3328, 2000. Birmili, W., Wiedensohler, A., Heintzenberg, J., and Lehmann, K.: Atmospheric Particle Number Size Distribution in Central Europe: Statistical Relations to Air Masses and Meteorology, J. Geophys. Res., D23, 32 005–32 018, 2001. Birmili, W., Berresheim, H., Plass-Dülmer, C., Elste, T., Gilge, S., Wiedensohler, A., and Uhrner, U.: The Hohenpeissenberg aerosol formation experiment (HAFEX): a long-term study including size-resolved aerosol, H2SO4, OH, and monoterpenes measurements, Atmos. Chem. Phys., 3, 361–376, 2003. Brock, C A., Trainer, M., Ryerson, T B., Neuman, J A., Parrish, D. D., Holloway, J. S., Nicks, D K J., Frost, G J., Hübler, G., and Fehsenfeld, F. C.: Particle growth in plumes of coal-fired power plants, J. Geophys. Res., 107, 4155, doi:10.1029/2001JD001062, 2002. Bukowiecki, N., Dommen, J., Prévôt, A. S. H., Weingartner, E., and Baltensperger, U.: Fine and ultrafine particles in the Zürich (Switzerland) area measured with a mobile laboratory: an assessment of the seasonal and regional variation throughout a year, Atmos. Chem. Phys., 3, 1477–1494, 2003. Chan, T W. and Mozurkewich, M.: Simplified representation of atmospheric aerosol size distributions using absolute principal component analysis, Atmos. Chem. Phys. 7, 875–886, 2007. Doyle, G. J.: Self-nucleation in the sulfuric acid-water system, J. Chem. Phys., 35, 795–799, 1961. Drewnick F., J. T. Jayne, M. R. Canagaratna, D. R. Worsnop, and Demerjian, K. L.: Measurement of Ambient Aerosol Composition During the PMTACS-NY 2001 Using an Aerosol Mass Spectrometer. Part I: Mass Concentrations, Aerosol Sci. Tech., 38(S1), 92-103, 2004. Ebert, M., Weinbruch, S., Hoffmann, P., and Ortner, H M.: The chemical composition and complex refractive index of rural and urban influenced aerosols determined by individual particle analysis, Atmos. Environ., 38, 6531–6545, 2004. Eder, B K.: A principal component analysis of SO<sub>4</sub> precipitation concentrations over the eastern United States, Atmos. Environ., 23, 2739–2750, 1989. Engler, C., Rose, D., Wehner, B, Wiedensohler, A., Bruggemann, E., Gnauk, T., Spindler, G., Tuch, T., and Birmili, W.: Size distributions of non-volatile particle residuals (Dp &lt; 800 nm) at a rural site in Germany and relation to air mass origin, Atmos. Chem. Phys. 7, 5785–5802, 2007. Gnanadesikan, R.: Methods for statistical data analysis of multivariate observations., New York, John Wiley and Sons, Inc., 1977. Haywood, J. M. and Boucher, O.: Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: A review, Rev. Geophys. 38, 513–543, 2000. HEI: Understanding the health effects of components of the particulate matter mix: progress and next steps, Tech. Rep 4, Health Effects Institute, Boston, MA, 2002. Heintzenberg, J., Birmili, W., Wiedensohler, A., Nowak, A., and Tuch, T.: Structure, variability and persistence of the submicrometre marine aerosol, Tellus B, 56(4), 357–367, 2004. Hering, S. V. and Friedlander, S. K.: Origins of Sulfur Size Distributions in the Los Angeles Basin, Atmos. Enriron. 16, 2647–2656, 1982. Hinds, W C.: Aerosol Technology, 2nd ed., John Wiley and Sons, New York, 1999. Huang, S., Rahn, K. A., and Arimoto, R.: Testing and optimizing two factor-analysis techniques on aerosol at Narragansett, Rhode Island, Atmos. Environ., 33, 2169–2185, 1999. Hussein, T., Puustinen, A., Aalto, P., Mäkelä, J., Hämeri, K., and Kulmala, M.: Urban aerosol number size distributions, Atmos. Chem. Phys., 4, 391–411, 2004. Hussein, T., Hämeri, K., Aalto, P., Paatero, P., and Kulmala, M.: Modal structure and spatial-temporal variations of urban and suburban aerosols in Helsinki, Finland, Atmos. Environ., 39, 1655–1668, 2005. Jaenicke, R. : Tropospheric aerosols, in: Aerosol-cloud-climate interactions, edited by: Hobbs, P V., Academic Press, San Diego, CA, 1–31, 1993. Jimenez, J. L., Jayne, J. T., Shi, Q., Kolb, C. E., Worsnop, D R., Yourshaw, I., Seinfeld, J H., Flagan, R C., Zhang, X., Smith, K A., Morris, J W., and Davidovits, P.: Ambient aerosol sampling with an Aerosol Mass Spectrometer, J. Geophys. Res., 108(D7), 8425, doi:10:1029/2001JD001213, 2003. John, W., Wall, S. M., Ondo, J. L., and Winklmayr, W.: Modes in the size distributions of atmospheric inorganic aerosol, Atmos. Environ., 24A, 2349–2359, 1990. John, W.: The characteristics of environmental and laboratory-generated aerosols, in: Aerosol measurement: Principles, techniques and applications, edited by: Willeke, K. and Baron, P. A., Van Nostrand Reinhold, New York, 1993. Jobson, B. T., Parrish, D. D., Goldan, P., Kuster, W., Fehsenfeld, F. C., Blake, D. R., Blake, N. J., and Niki, H.: Spatial and temporal variability of nonmethane hydrocarbon mixing ratios and their relation to photochemical lifetime, J. Geophys. Res. A, 103, 13 557–13 567, 1998. Junge, C. E.: Residence time and variability of tropospheric trace gases, Tellus, 16, 477–488, 1974. Kerminen, V. M. and Wexler, A. S.: The occurrence of sulfuric acid-water nucleation in plumes: Urban environment, Tellus, 48B, 65–82, 1996. Ketzel, M P., Wahlin, A., Kristensson, E., Swietlicki, R., Berkowicz, O J., Nielsen, and Palmgren, F.: Particle size distribution and particle mass measurements at urban, near-city and rural level in the Copenhagen area and Southern Sweden, Atmos. Chem. Phys., 4, 281–292, 2004. Kittelson, D.: Engines and Nanoparticles: A Review, J. Aerosol Sci., 29, 575–588, 1998. Kulmala, M., Suni, T., Lehtinen, K. E. J., Dal Maso, M., Boy, M., Reissell, A., Rannik, U., Aalto, P., Keronen, P., Hakola, H., Ba\"ck, J., Hoffmann, T., Vesala T., and Hari, P.: A new feedback mechanism linking forests, aerosols, and climate, Atmos. Chem. Phys., 3, 6093–6107, 2003. 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, 2004. Mäkelä, J. M., Dal Maso, M., Laaksonen, A., Kulmala, M., Pirjola, L., Keronen, P., and Laakso, L.: Characteristics of the aerosol particle formation events observed at a boreal forest site in southern Finland, Boreal Environ. Res., 5, 299–313, 2000. McFiggans, G., Alfarra, M. R., Allan, J., Bower, K., Coe, H., Cubison, M., Topping, D., Williams, P., Decesari, S., Facchini, C., and Fuzzi, S.: Simplification of the representation of the organic component of atmospheric particulates, Faraday Discuss., 130, 341–362, 2005. Mejia J. F., Morawska L., and Mengersen, K.: Spatial variation in particle number size distributions in a large metropolitan area, Atmos. Chem. Phys., 8, 1127–1138, 2008. Meng, Z. and Seinfield, J. H.: On the source of the submicrometer droplet mode of urban and regional aerosols, Aerosol Sci. Technol., 20, 253–265, 1994. Morawska, L., Keogh, D U., Thomas, S B., and Mengersen, K.: Modality in ambient particle size distributions and its potential as a basis for developing air quality regulation, Atmos. Environ., 42, 1617–1628, 2008. Morrison, D F.: Multivariate statistical methods, 2nd ed., McGraw-Hill, New York, 1976. Mulaik, S. A.: The foundations of factor analysis, McGraw-Hill, New York, 1972. Oberdörster, G.: Nanotoxicology: An emerging discipline evolving from studies of ultrafine particles, Environ. Health Persp., 113(7), 823–839, 2005. Ondov, J M. and Wexler, A S.: Where Do Particulate Toxins Reside? An Improved Paradigm for the Structure and Dynamics of the Urban Mid-Atlantic Aerosol, Environ. Sci. Technol., 32, 17, 2547–2555, 1998. Pope, C A., Burnett, R T., Thun, M J., et~al.: Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution, J. Aerosol Med., 287, 1132–1141, 2002. Pugatshova, A., Reinart, A., and Tamm, E.: Features of the multimodal aerosol size distribution depending on the air mass origin in the Baltic region, Atmos. Environ., 41, 4408–4422, 2007. Puustinen, A., Hämeri, K. , Pekkanen, J., Kulmala, M., Hartog, J., de Meliefste, K., Brink, H., Kos, G. T., Katsouyanni, K., Karakatsani, A., Kotronarou, A., Kavouras, I., Meddings, C., Thomas, S., Harrison, R., Ayres, J., Zee, S. C., Der, V., and Hoek, G.: Spatial variation of particle number and mass over four European cities, Atmos. Environ., 41, 6622–6636, 2007. Ramanathan, V., Crutzen, P. J., Kiehl, J. T., and Rosenfeld, D.: Aerosol, climate, and the hydrological cycle, Science, 294, 2119–2124, 2001. Seinfeld, J H. and Pandis, S P.: Atmospheric Chemistry and Physics, 2nd ed., John Wiley, New York, 2006. Sioutas, C., Delfino, R J., and Singh, M.: Exposure assessment for atmospheric ultrafine particles (UFP) and implications in epidemiological research, Environ. Health Persp., 113(8), 947–955, 2005. Stott, P. A., Tett, S. F. B., Jones, G. S., Allen, M. R., Mitchell, J. F. B., and Jenkins, G. J.: External control of 20$^th$ century temperature by natural and anthropogenic forcings, Science, 290, 2133–2137, 2000. Tuch, T., Herbarth, O., Franck, U., Peters, A., Wehner, B., Wiedensohler, A., and Heintzenberg, J.: Weak correlation of ultrafine aerosol particle concentrations &lt;800 nm between two sites within one city, J. Expo. Sci. Env. Epid., 16, 486–490, 2006. Tunved, P., Ström, J., and Hansson, H C.: An investigation of processes controlling the evolution of the boundary layer aerosol size distribution properties at the Swedish background station Aspvreten, Atmos. Chem. Phys., 4, 2581–2592, 2004. Voigtländer, J., Tuch, T., Birmili, W., and Wiedensohler, A.: Correlation between traffic density and particle size distribution in a street canyon and the dependence on wind direction, Atmos. Chem. Phys., 6, 4275–4286, 2006. Wehner, B., Birmili, W., Gnauk, T., and Wiedensohler, A.: Particle number size distributions in a street canyon and their transformation into the urban background: Measurements and a simple model study, Atmos. Environ., 36, 2215–2223, 2002. Wehner, B., and Wiedensohler, A.: Long term measurements of submicrometer urban aerosols: statistical analysis for correlations with meteorological conditions and trace gases, Atmos. Chem. Phys., 3, 867–879, 2003. Wehner, B., Siebert, H., Stratmann, F., Tuch, T., Wiedensohler, A., Petäjä, T., Dal Maso, M., and Kulmala, M.: Horizontal homogeinity and vertical extent of new particle formation events, Tellus, 59B, 362–371, 2007. Whitby, K.T.: The physical characteristics of sulphur aerosols, Atmos. Environ., 12, 135–159, 1978. WHO: World Health Report 2002, Tech. Rep., World Health Organisation, Genova, 2002.