References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-7-5675-2007

Secondary organic aerosol in the global aerosol – chemical transport model Oslo CTM2

Hoyle

C. R.

¹ Berntsen

¹ Myhre

¹ Isaksen

I. S. A.

Department of Geosciences, University of Oslo, Norway

16 11 2007

7 21 5675 5694

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.net/7/5675/2007/acp-7-5675-2007.html

The full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/5675/2007/acp-7-5675-2007.pdf

The global chemical transport model Oslo CTM2 has been extended to include the formation, transport and deposition of secondary organic aerosol (SOA). Precursor hydrocarbons which are oxidised to form condensible species include both biogenic species such as terpenes and isoprene, as well as species emitted predominantly by anthropogenic activities (toluene, m-xylene, methylbenzene and other aromatics). A model simulation for 2004 gives an annual global SOA production of approximately 55 Tg. Of this total, 2.5 Tg is found to consist of the oxidation products of anthropogenically emitted hydrocarbons, and about 15 Tg is formed by the oxidation products of isoprene. The global production of SOA is increased to about 69 Tg yr−1 by allowing semi-volatile species to partition to ammonium sulphate aerosol. This brings modelled organic aerosol values closer to those observed, however observations in Europe remain significantly underestimated. Allowing SOA to partition into ammonium sulphate aerosol increases the contribution of anthropogenic SOA from about 4.5% to 9.4% of the total production. Total modelled organic aerosol (OA) values are found to represent a lower fraction of the measured values in winter (when primary organic aerosol (POA) is the dominant OA component) than in summer, which may be an indication that estimates of POA emissions are too low. Additionally, for measurement stations where the summer OA values are higher than in winter, the model generally underestimates the increase in summertime OA. In order to correctly model the observed increase in OA in summer, additional SOA sources or formation mechanisms may be necessary. The importance of NO3 as an oxidant of SOA precursors is found to vary regionally, causing up to 50%–60% of the total amount of SOA near the surface in polluted regions and less than 25% in more remote areas, if the yield of condensible oxidation products for β-pinene is used for NO3 oxidation of all terpenes. Reducing the yield for α-pinene and limonene oxidation in line with recent measurements reduces the global fraction of SOA formed from NO3 oxidation products from 27% to about 21%. This study underscores the need for SOA to be represented in a more realistic way in global aerosol models in order to better reproduce observations of organic aerosol burdens in industrialised and biomass burning regions.

References 1

Ackerman, A S., Toon, O B., Stevens, D E., Heymsfield, A J., Ramanathan, V., and Welton, E J.: Reduction of Tropical Cloudiness by Soot, Science, 288, 1042–1047, 2000.

Albrecht, B A.: Aerosols, Cloud Microphysics, and Fractional Cloudiness, Science, 245, 1227–1230, 1989.

Allan, B J., Plane, J. M C., Coe, H., and Shillito, J.: Observations of NO3 concentration profiles in the troposphere, J. Geophys. Res., 107(D21), 4588 \doi10.1029/2002JD002112, 2002.

Atkinson, R.: Gas-phase tropospheric chemistry of organic compounds: a review , Atmospheric Environment Part A-General Topics, 24, 1–41, 1990.

Atkinson, R.: Gas-phase tropospheric chemistry of organic compounds, J. Phys. Chem. Ref. Data, Monogr., 2, 1–216, 1994.

Berglen, T F., Berntsen, T K., Isaksen, I. S A., and Sundet, J K.: A global model of the coupled sulfur/oxidant chemistry in the troposphere: The sulfur cycle, J. Geophys. Res., 109, D19310, \doi10.1029/2003JD003948, 2004.

Berntsen, T K. and Isaksen, I S A.: A global three-dimensional chemical transport model for the troposphere 1. Model description and CO and ozone results, J. Geophys. Res., 102, 21 239–21 280, \doi10.1029/97JD01140, 1997.

Bond, T C., Streets, D G., Yarber, K F., Nelson, S M., Woo, J.-H., and Klimont, Z.: A technology-based global inventory of black and organic carbon emissions from combustion, J. Geophys. Res.-Atmos., 109, D14203, \doi10.1029/2003JD003697, 2004.

Bonn, B. and Moorgat, G K.: New particle formation during a- and b-pinene oxidation by O3, OH and NO3, and the influence of water vapour: particle size distribution studies, Atmos. Chem. Phys., 2, 183–196, 2002.

Brown, S S., Osthoff, H D., Stark, H., Dubé, W P., Ryerson, T B., Warneke, C., de Gouw, J A., Wollny, A G., Parrish, D D., Fehsenfeld, F C., and Ravishankara, A R.: Aircraft observations of daytime NO3 and N2O$_5$ and their implications for tropospheric chemistry, J. Photoch. Photobio. A, 176, 270–278, 2005.

Brunner, D., Staehelin, J., Rogers, H L., Köhler, M O., Pyle, J A., Hauglustaine, D., Jourdain, L., Berntsen, T K., Gauss, M., Isaksen, I. S A., Meijer, E., van Velthoven, P., Pitari, G., Mancini, E., Grew, V., and Sausen, R.: An evaluation of the performance of chemistry transport models by comparison with research aircraft observations. Part 1: Concepts and overall model performance, Atmos. Chem. Phys., 3, 1609–1631, 2003.

Chung, S H. and Seinfeld, J H.: Global distribution and climate forcing of carbonaceous aerosols, J. Geophys. Res.-Atmos., 107(D19), 4407, \doi10.1029/2001JD001397, 2002.

Cooke, W F., Liousse, C., Cachier, H., and Feichter, J.: Construction of a 1\degree×1\degree fossil fuel emission data set for carbonaceous aerosol and implementation and radiative impact in the ECHAM4 model, J. Geophys. Res., 104(D18), 22 137–22 162, \doi10.1029/1999JD900187, 1999.

Derwent, R G., Collins, W J., Jenkin, M E., Johnson, C E., and Stevenson, D S.: The Global Distribution of Secondary Particulate Matter in a 3-D Lagrangian Chemistry Transport Model, J. Atmos. Chem., 44, 57–95, 2003.

Dindorf, T., Kuhn, U., Ganzeveld, L., Schebeske, G., Ciccioli, P., Holzke, C., Köble, R., Seufert, G., and Kesselmeier, J.: Significant light and temperature dependent monoterpene emissions from European beech (Fagus sylvatica L.) and their potential impact on the European volatile organic compound budget, J. Geophys. Res.-Atmos., 111, D16305, \doi10.1029/2005JD006751, 2006.

Donahue, N M., Robinson, A L., Stanier, C O., and Pandis, S N.: Coupled partitioning, dilution and chemical aging of semivolatile organics, Environ. Sci. Technol., 40, 2635–2643, 2006.

Edney, E O., Driscoll, D J., Speer, R E., Weathers, W S., Kleindienst, T E., Li, W., and Smith, D F.: Impact of aerosol liquid water on secondary organic aerosol yields of irradiated toluene/propylene/NOx/(NH4)2SO4/air mixtures, Atmos. Environ., 34, 3907–3919, 2000.

Geyer, A., Alicke, B., Ackermann, R., Martinez, M., Harder, H., Brune, W., di Carlo, P., Williams, E., Jobson, T., Hall, S., Shetter, R., and Stutz, J.: Direct observations of daytime NO3: Implications for urban boundary layer chemistry, J. Geophys. Res.-Atmos., 108(D12), 4368, \doi10.1029/2002JD002967, 2003.

Granier, C., Lamarque, J F., Mieville, A., Muller, J F., Olivier, J., Orlando, J., Peters, J., Petron, G., Tyndall, G., and Wallens, S.: POET, a database of surface emissions of ozone precursors, available on internet at http://www.aero.jussieu.fr/projet/ACCENT/POET.php, 2005.

Greenberg, J P., Guenther, A., Harley, P., Otter, L., Veenendaal, E M., Hewitt, C N., James, A E., and Owen, S M.: Eddy flux and leaf-level measurements of biogenic VOC emissions from mopane woodland of Botswana, J. Geophys. Res.-Atmos., 108(D13), 8466, \doi10.1029/2002JD002317, 2003.

Griffin, R J., Cocker, D R., Seinfeld, J H., and Dabdub, D.: Estimate of global atmospheric organic aerosol from oxidation of biogenic hydrocarbons, Geophys. Res. Lett., 26, 2721–2724, \doi10.1029/1999GL900476, 1999a.

Griffin, R J., Flagan, R C., and Seinfeld, J H.: Organic aerosol formation from the oxidation of biogenic hydrocarbons, J. Geophys. Res., 104, 3555–3568, \doi10.1029/1998JD100049, 1999b.

Guenther, A., Hewitt, C N., Erickson, D., Fall, R., Geron, C., Graedel, T., Harley, P., Klinger, L., Lerdau, M., McKay, W A., Pierce, T., Scholes, B., Steinbrecher, R., Tallamraju, R., Taylor, J., and Zimmerman, P.: A global model of natural volatile organic compound emissions, J. Geophys. Res., 100, 8873–8892, \doi10.1029/94JD02950, 1995.

Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181–3210, 2006.

Han, J S., Moon, K J., Kong, B J., Lee, S J., Kim, J E., and Kim, Y J.: Seasonal variation of chemical composition in fine particles at Gosan, Korea, Environ. Monit. Assess., 107, 221–237, 2005.

Hansen, J., Sato, M., and Ruedy, R.: Radiative forcing and climate response, J. Geophys. Res., 102, 6831–6864, \doi10.1029/96JD03436, 1997.

Haywood, J M. and Shine, K P.: The effect of anthropogenic sulfate and soot aerosol on the clear sky planetary radiation budget, Geophys. Res. Lett., 22, 603–606, \doi10.1029/95GL00075, 1995.

Henze, D K. and Seinfeld, J H.: Global secondary organic aerosol from isoprene oxidation, Geophys. Res. Lett., 33, L09812, \doi10.1029/2006GL025976, 2006.

Hesstvedt, E., Hov, Ø., and Isaksen, I S A.: Quasi-Steady-State Approximations in Air-Pollution Modeling - Comparison of Two Numerical Schemes for Oxidant Prediction, Int. J. Chem. Kinet., 10, 971–994, 1978.

Hoffmann, T., Odum, J R., Bowman, F., D.Collins, Klockow, D., Flagan, R C., and Seinfeld, J H.: Formation of Organic Aerosols from the Oxidation of Biogenic Hydrocarbons, J. Atmos. Chem., 26, 189–222, 1997.

Holtslag, A. A M. and Ulden, A. P V.: A Simple Scheme for Daytime Estimates of the Surface Fluxes from Routine Weather Data, J. Clim. Appl. Meteorol., 22, 517–529, 1983.

IPCC: Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 881 pp., 2001.

Isaksen, I. S A., Zerefos, C., Kourtidis, K., Meleti, C., Dalsoren, S B., Sundet, J K., Grini, A., Zanis, P., and Balis, D.: Tropospheric ozone changes at unpolluted and semipolluted regions induced by stratospheric ozone changes, J. Geophys. Res., 110, D02302, doi:10.1029/2004JD004618, 2005.

Jones, A P.: Indoor air quality and health, Atmos. Environ., 33, 4535–4564, 1999.

Kanakidou, M., Tsigaridis, K., Dentener, F J., and Crutzen, P J.: Human-activity-enhanced formation of organic aerosols by biogenic hydrocarbon oxidation, J. Geophys. Res., 105, 9243–9254, \doi10.1029/1999JD901148, 2000.

Kanakidou, M., Seinfeld, J H., Pandis, S N., Barnes, I., Dentener, F J., Facchini, M C., van Dingenen, R., Ervens, B., Nenes, A., Nielsen, C J., Swietlicki, E., Putaud, J P., Balkanski, Y., Fuzzi, S., Horth, J., Moortgat, G K., Winterhalter, R., Myhre, C E L., Tsigaridis, K., Vignati, E., Stephanou, E G., and Wilson, J.: Organic aerosol and global climate modelling: a review, Atmos. Chem. Phys., 5, 1053–1123, 2005.

Kesselmeier, J. and Staudt, M.: Biogenic Volatile Organic Compounds (VOC): An Overview on Emission, Physiology and Ecology, J. Atmos. Chem., 33, 23–88, 1999.

Kinne, S., Schulz, M., Textor, C., Guibert, S., Balkanski, Y., Bauer, S E., Berntsen, T., Berglen, T F., Boucher, O., Chin, M., Collins, W., Dentener, F., Diehl, T., Easter, R., Feichter, J., Fillmore, D., Ghan, S., Ginoux, P., Gong, S., Grini, A., Hendricks, J., Herzog, M., Horowitz, L., Isaksen, I., Iversen, T., Kirkevåg, A., Kloster, S., Koch, D., Kristjansson, J E., Krol, M., Lauer, A., Lamarque, J F., Lesins, G., Liu, X., Lohmann, U., Montanaro, V., Myhre, G., Penner, J., Pitari, G., Reddy, S., Seland, O., Stier, P., Takemura, T., and Tie, X.: An AeroCom initial assessment – optical properties in aerosol component modules of global models, Atmos. Chem. Phys., 6, 1815–1834, 2006.

Kleindienst, T E., Smith, D F., Li, W., Edney, E O., Driscoll, D J., Speer, R E., and Weathers, W S.: Secondary organic aerosol formation from the oxidation of aromatic hydrocarbons in the presence of dry submicron ammonium sulphate aerosol, Atmos. Environ., 33, 3669–3681, 1999.

Kroll, J H., Chan, A. W H., Ng, N L., Flagan, R C., and Seinfeld, J H.: Reactions of semivolatile organics and their effects on secondary organic aerosol formation, Environ. Sci. Technol., 41, 3545–3550, 2007.

Kuhn, U., Rottenberger, S., Biesenthal, T., Wolf, A., Schebeske, G., Ciccioli, P., Brancaleoni, E., Frattoni, M., Tavares, T M., and Kesselmeier, J.: Isoprene and monoterpene emissions of Amaz\^onian tree species during the wet season: Direct and indirect investigations on controlling environmental functions, J. Geophys. Res.-Atmos., 107(D20), 8069, \doi10.1029/2000JD000303, 2002.

Lack, D A., Tie, X X., Bofinger, N D., Wiegand, A N., and Madronich, S.: Seasonal variability of secondary organic aerosol: A global modeling study, J. Geophys. Res.-Atmos., 109, D03203, \doi10.1029/2003JD003418, 2004.

Lathière, J., Hauglustaine, D A., Friend, A D., de Noblet-Ducoudré, N., Viovy, N., and Folberth, G A.: Impact of climate variability and land use changes on global biogenic volatile organic compound emissions, Atmos. Chem. Phys., 6, 2129–2146, 2006.

Liousse, C., Penner, J E., Chuang, C., Walton, J J., Eddleman, H., and Cachier, H.: A global three-dimensional model study of carbonaceous aerosols, J. Geophys. Res., 101, 19 411–19 432, \doi10.1029/95JD03426, 1996.

Maria, S F., Russell, L M., Gilles, M K., and Myneni, S C B.: Organic Aerosol Growth Mechanisms and Their Climate-Forcing Implications, Science, 306, 1921–1924, \doi10.1126/science.1103491, 2004.

Myhre, G., Berntsen, T K., Haywood, J M., Sundet, J K., Holben, B N., Johnsrud, M., and Stordal, F.: Modelling the solar radiative impact of aerosols from biomass burning during the Southern African Regional Science Initiative (SAFARI-2000) experiment, J. Geophys. Res.-Atmos., 108(D13), 8501, \doi10.1029/2002JD002313, 2003.

Myhre, G., Bellouin, N., Berglen, T F., Berntsen, T K., Boucher, O., Grini, A., Isaksen, I S A., Johnsrud, M., Mishchenko, M I., Stordal, F., and Tanré, D.: Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean, Tellus B, 59, 115–129, \doi10.1111/j.1600-0889.2006.00226.x, 2007.

Northcross, A L. and Jang, M.: Heterogeneous SOA yield from ozonlysis of monoterpenes in the presence of inorganic acid, Atmos. Environ., 41, 1483–1493, 2007.

Odum, J R., Jungkamp, T. P W., Griffin, R J., Flagan, R C., and Seinfeld, J H.: The Atmospheric Aerosol-Forming Potential of Whole Gasoline Vapor, Science, 276, 96–99, 1997.

Ostro, B. and Chestnut, L.: Assessing the health benifits of reducing particulate matter air pollution in the United States, Environ. Res., 76, 94–106, 1998.

Otter, L., Guenther, A., Wiedinmyer, C., Fleming, G., Harley, P., and Greenberg, J.: Spatial and temporal variations in biogenic volatile organic compound emissions for Africa south of the equator, Journal of Geophysical Research (Atmospheres), 108(D13), 8505, \doi10.1029/2002JD002609, 2003.

Penkett, S A., Blake, N J., Lightman, P., Marsh, A R W., Anwyl, P., and Butcher, G.: The seasonal variation of nonmethane hydrocarbons in the free troposphere over the North Atlantic Ocean – Possible evidence for extensive reaction of hydrocarbons with the nitrate radical, J. Geophys. Res., 98, 2865–2885, 1993.

Penner, J E., Chuang, C C., and Grant, K.: Climate forcing by carbonaceous and sulfate aerosols, Clim. Dynam., 14, 839–851, 1998.

Pun, B K., Wu, S.-Y., Seigneur, C., Seinfeld, J H., Griffin, R J., and Pandis, S N.: Uncertainties in Modeling Secondary Organic Aerosols: Three-Dimensional Modeling Studies in Nashville/Western Tennessee, Environ. Sci. Technol., 37, 3647–3661, 2003.

Puxbaum, H., Rendl, J., Allabashi, R., Otter, L., and Scholes, M C.: Mass balance of the atmospheric aerosol in a South African subtropical savanna (Nylsvley, May 1997), J. Geophys. Res., 105, 20 697–20 706, \doi10.1029/2000JD900306, 2000.

Robinson, A L., Donahue, N M., Shrivastava, M K., Weitkamp, E A., Sage, A M., Grieshop, A P., Lane, T E., Pierce, J R., and Pandis, S N.: Rethinking Organic Aerosols: Semivolatile Emissions and Photochemical Aging, Science, 315, 1259–1262, \doi10.1126/science.1133061, 2007.

Schulz, M., Textor, C., Kinne, S., Balkanski, Y., Bauer, S., Berntsen, T., Berglen, T., Boucher, O., Dentener, F., Guibert, S., Isaksen, I S A., Iversen, T., Koch, D., Kirkevåg, A., Liu, X., Montanaro, V., Myhre, G., Penner, J E., Pitari, G., Reddy, S., Seland, Ø., Stier, P., and Takemura, T.: Radiative forcing by aerosols as derived from the AeroCom present-day and pre-industrial simulations, Atmos. Chem. Phys., 6, 5225–5246, 2006.

Shrivastava, M K., Lipsky, E M., Stanier, C O., and Robinson, A L.: Modeling semivolatile organic aerosol mass emissions from combustion systems, Environ. Sci. Technol., 40, 2671–2677, 2006.

S.Moukhtar, Bessagnet, B., Rouil, L., and Simon, V.: Monoterpene emissions from Beech (Fagus sylvatica) in a French forest and impact on secondary pollutants formation at regional scale, Atmos. Environ., 39, 3535–3547, 2005.

Spittler, M., Barnes, I., Bejan, I., Brockmann, K J., Benter, T., and Wirtz, K.: Reactions of NO3 radicals with limonene and α-pinene: Product and SOA formation, Atmos. Environ., 40, 116–127, 2006.

Takami, A., Miyoshi, T., Shimono, A., and Hatakeyama, S.: Chemical composition of fine aerosol measured by AMS at Fukue Island, Japan during APEX period, Atmos. Environ., 39, 4913–4924, 1995.

Textor, C., Schulz, M., Guibert, S., Kinne, S., Balkanski, Y., Bauer, S., Berntsen, T., Berglen, T., Boucher, O., Chin, M., Dentener, F., Diehl, T., Easter, R., Feichter, H., Fillmore, D., Ghan, S., Ginoux, P., Gong, S., Grini, A., Hendricks, J., Horowitz, L., Huang, P., Isaksen, I., Iversen, I., Kloster, S., Koch, D., Kirkevåg, A., Kristjansson, J E., Krol, M., Lauer, A., Lamarque, J F., Liu, X., Montanaro, V., Myhre, G., Penner, J., Pitari, G., Reddy, S., Seland, Ø., Stier, P., Takemura, T., and Tie, X.: Analysis and quantification of the diversities of aerosol life cycles within AeroCom, Atmos. Chem. Phys., 6, 1777–1813, 2006.

Tsigaridis, K. and Kanakidou, M.: Global modelling of secondary organic aerosol in the troposphere: A sensitivity analysis, Atmos. Chem. Phys., 3, 2879–2929, 2003.

Tsigaridis, K., Lathière, J., Kanakidou, M., and Hauglustaine, D A.: Naturally driven variability in the global secondary organic aerosol over a decade, Atmos. Chem. Phys., 5, 1891–1904, 2005.

Turpin, B J. and Lim, H.-J.: Species contributions to PM2.5 mass concentrations: revisiting common assumptions for estimating organic mass, Aerosol Sci. Technol., 35, 602–610, \doi10.1080/02786820119445, 2001.

Twomey, S.: The Nuclei of Natural Cloud Formation Part II: The Supersaturation in Natural Clouds and the Variation of Cloud Droplet Concentration, Geofisica pura e applicata, 43, 243–249, 1959.

Twomey, S.: The Influence of Pollution on the Shortwave Albedo of Clouds, J. Atmos. Sci., 34, 1149–1152, 1977.

van der Werf, G R., Randerson, J T., Giglio, L., Collatz, G J., Kasibhatla, P S., and Arellano, Jr., A F.: Interannual variability in global biomass burning emissions from 1997 to 2004, Atmos. Chem. Phys., 6, 3423–3441, 2006.

van Noije, T P C., Eskes, H J., Dentener, F J., Stevenson, D S., Ellingsen, K., Schultz, M G., Wild, O., Amann, M., Atherton, C S., Bergmann, D J., Bey, I., Boersma, K F., Butler, T., Cofala, J., Drevet, J., Fiore, A M., Gauss, M., Hauglustaine, D A., Horowitz, L W., Isaksen, I S A., Krol, M C., Lamarque, J.-F., Lawrence, M G., Martin, R V., Montanaro, V., Müller, J.-F., Pitari, G., Prather, M J., Pyle, J A., Richter, A., Rodriguez, J M., Savage, N H., Strahan, S E., Sudo, K., Szopa, S., and van Roozendael, M.: Multi-model ensemble simulations of tropospheric NO2 compared with GOME retrievals for the year 2000, Atmos. Chem. Phys., 6, 2943–2979, 2006.

Virkkula, A., Teinilã, K., Hillamo, R., V.-M.Kerminen, Saarikoski, S., Aurela, M., J.Viidanoja, Paatero, J., Koponen, I K., and Kulmala, M.: Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic site, Atmos. Chem. Phys., 6, 3407–3421, 2006.

Volkamer, R., Jimenez, J L., San Martini, F., Dzepina, K., Zhang, Q., Salcedo, D., Molina, L T., Worsnop, D R., and Molina, M J.: Secondary organic aerosol formation from anthropogenic air pollution: Rapid and higher than expected, Geophys. Res. Lett., 33, L17811, \doi10.1029/2006GL026899, 2006.

Vrekoussis, M., Kanakidou, M., Mihalopoulos, N., Crutzen, P J., Lelieveld, J., Perner, D., Berresheim, H., and Baboukas, E.: Role of the NO3 radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign, Atmos. Chem. Phys., 4, 169–182, 2004.

Vrekoussis, M., Liakakou, E., Mihalopoulos, N., Kanakidou, M., Crutzen, P J., and Lelieveld, J.: Formation of HNO3 and NO$_3^-$ in the anthropogenically-influenced eastern Mediterranean marine boundary layer, Geophys. Res. Lett., 33, L05811, \doi10.1029/2005GL025069, 2006.

Yang, H., Yu, J Z., Ho, S. S H., Xu, J., W.-S.Wu, Wan, C H., Wang, X., Wang, X., and Wang, L.: The chemical composition of inorganic and carbonaceous materials in PM$_2.5$ in Nanjing, China, Atmos. Environ., 39, 3735–3749, 2005.

Yttri, K E., Aas, W., Bjerke, A., Ceburnis, D., Dye, C., Emblico, L., Facchini, M C., Forster, C., Hanssen, J E., Hansson, H C., Jennings, S G., Maenhaut, W., Putaud, J P., , and Tørseth, K.: Elemental and organic carbon in PM$_10$: a one year measurement campaign within the European Monitoring and Evaluation Programme EMEP, Atmos. Chem. Phys. Discuss., 7, 3859–3899, 2007.

Zhang, Q., Worsnop, D R., Canagaratna, M R., and Jimenez, J L.: Hydrocarbon-like and oxygenated organic aerosols in Pittsburgh: insights into sources and processes of organic aerosols, Atmos. Chem. Phys., 5, 3289–3311, 2005.