Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 9 19 2009 10.5194/acp-9-7643-2009 http://www.atmos-chem-phys.net/9/7643/2009/ http://www.atmos-chem-phys.net/9/7643/2009/acp-9-7643-2009.html http://www.atmos-chem-phys.net/9/7643/2009/acp-9-7643-2009.pdf 7643 7655 2009-10-13 Chemical apportionment of southern African aerosol mass and optical depth B. I. Magi brian.magi@noaa.gov Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey, USA This study characterizes the aerosol over extratropical and tropical southern Africa during the biomass burning season by presenting an aerosol mass apportionment and aerosol optical properties. Carbonaceous aerosol species account for 54% and 83% of the extratropical and tropical aerosol mass, respectively, which is consistent with the fact that the major source of particulate matter in southern Africa is biomass burning. This mass apportionment implies that carbonaceous species in the form of organic carbon (OC) and black carbon (BC) play a critical role in the aerosol optical properties. By combining the in situ measurements of aerosol mass concentrations with concurrent measurements of aerosol optical properties at a wavelength of 550 nm, it is shown that 80–90% of the aerosol scattering is due to carbonaceous aerosol, and the derived mass scattering cross sections (MSC) for OC and BC are 3.9±0.6 m²/g and 1.6±0.2 m²/g, respectively. Derived values of mass absorption cross sections (MAC) for OC and BC are 0.7±0.6 m²/g and 8.2±1.1 m²/g, respectively. The values of MAC imply that ~26% of the aerosol absorption in southern Africa is due to OC, with the remainder due to BC. The results in this study provide important constraints for aerosol properties in a region dominated by biomass burning and should be integrated into climate models to improve aerosol simulations. % vor jede Referenz Bohren, C. F. and Huffman, D. R.: Absorption and scattering of light by small particles, John Wiley and Sons, New York, 1983. Bond, T. C., Streets, D. G., Yarber, K. F., Nelson, S. M., Woo, J., and Klimont, Z.: A technology-based global inventory of black and organic carbon emissions from combustion, J. Geophys. Res., 109, D14203, doi:10.1029/2003JD003697, 2004. Bond, T. C. and Bergstrom, R. W.: Light Absorption by Carbonaceous Particles: An Investigative Review, Aerosol Sci. Tech., 40, 27–67, 2006. Bond, T. C., Habib, G., and Bergstrom, R. W.: Limitations in the enhancement of visible light absorption due to mixing state, J. Geophys. Res., 111, D20211, doi:10.1029/2006JD007315, 2006. Bond, T. C., Bhardwaj, E., Dong, R., Jogani, R., Jung, S., Roden, C., Streets, D. G., and Trautmann, N. M.: Historical emissions of black and organic carbon aerosol from energy-related combustion, 1850–2000, Glob. Biogeochem. Cyc., 21, GB2018, doi:10.1029/2006GB002840, 2007. Dentener, F., Kinne, S., Bond, T., Boucher, O., Cofala, J., Generoso, S., Ginoux, P., Gong, S., Hoelzemann, J. J., Ito, A., Marelli, L., Penner, J. E., Putaud, J.-P., Textor, C., Schulz, M., van der Werf, G. R., and Wilson, J.: Emissions of primary aerosol and precursor gases in the years 2000 and 1750 prescribed data-sets for AeroCom, Atmos. Chem. Phys., 6, 4321–4344, 2006. Eatough, D. J., Eatough, N. L., Pang, Y., Sizemore, S., Kirchstetter, T. W., Novakov, T., and Hobbs, P. V.: Semivolatile particulate organic material in southern Africa during SAFARI 2000, J. Geophys. Res., 108(D13), 8479, doi:10.1029/2002JD002296, 2003. Formenti, P., Elbert, W., Maenhaut, W., Haywood, J., Osborne, S., and Andreae, M. O.: Inorganic and carbonaceous aerosols during the Southern African Regional Science Initiative (SAFARI 2000) experiment: Chemical characteristics, physical properties, and emission data for smoke from African biomass burning, J. Geophys. Res., 108(D13), 8488, doi:10.1029/2002JD002408, 2003. Gao, S., Hegg, D. A., Hobbs, P. V., Kirchstetter, T. W., Magi, B. I., and Sadilek, M.: Water-soluble organic components in aerosols associated with savanna fires in southern Africa: Identification, evolution, and distribution, J. Geophys. Res., 108(D13), 8491, doi:10.1029/2002JD002324, 2003. Garstang, M., Tyson, P. D., Swap, R., Edwards, M., Kallberg, P., and Lindesay, J. A.: Horizontal and vertical transport of air over southern Africa, J. Geophys. Res., 101(D19), 23721–23736, 1996. Giglio, L., Descloitres, J., Justice, C. O., and Kaufman, Y. J.: An enhanced contextual fire detection algorithm for MODIS, Remote Sens. Environ., 87(2–3), 273–282, 2003. Giglio, L., G. R. van der Werf, J. T. Randerson, G. J. Collatz, and P. Kasibhatla, Global estimation of burned area using MODIS active fire observations, Atmos. Chem. Phys., 6, 957-974, 2006. Ginoux, P., Horowitz, L. W., Ramaswamy, V., Geogdzhayev, I. V., Holben, B. N., Stenchikov, G., and Tie, X.: Evaluation of aerosol distribution and optical depth in the Geophysical Fluid Dynamics Laboratory coupled model CM2.1 for present climate, J. Geophys. Res., 111, D22210, doi:10.1029/2005JD006707, 2006. Hegg, D. A., Larson, T., and Yuen, P. F.: A theoretical study of the effect of relative humidity on light scattering by tropospheric aerosols, J. Geophys. Res., 98, 18435–18439, 1993. Hobbs, P. V., Sinha, P., Yokelson, R. J., Bertschi, I. T., Blake, D. R., Gao, S., Kirchstetter, T. W., Novakov, T., and Pilewskie, P.: Evolution of gases and particles from a savanna fire in South Africa, J. Geophys. Res., 108(D13), 8485, doi:10.1029/2002JD002352, 2003. 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. 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. Kirchstetter, T. W., Novakov, T., Hobbs, P. V., and Magi, B.: Airborne measurements of carbonaceous aerosols in southern Africa during the dry, biomass burning season, J. Geophys. Res., 108(D13), 8476, doi:10.1029/2002JD002171, 2003. Kirchstetter, T. W., Novakov, T., and Hobbs, P. V.: Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon, J. Geophys. Res., 109(D21), D21208, 8476, doi:10.1029/2004JD004999, 2004. Li, J., Posfai, M., Hobbs, P. V., and Buseck, P. R.: Individual aerosol particles from biomass burning in southern Africa: 2. Compositions and aging of inorganic particles, J. Geophys. Res., 108(D13), 8484, doi:10.1029/2002JD002310, 2003. 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, 19411–19432, 1996. Liu, L., Lacis, A. A., Carlson, B. E., Mishchenko, M. I., and Cairns, B.: Assessing Goddard Institute for Space Studies ModelE aerosol climatology using satellite and ground-based measurements: A comparison study, J. Geophys. Res., 111, D20212, doi:10.1029/2006JD007334, 2006. Maenhaut, W., Salma, I., Cafmeyer, J., Annegarn, H. J., and Andreae, M. O.: Regional atmospheric aerosol composition and sources in the eastern Transvaal, South Africa, and impact of biomass burning, J. Geophys. Res., 101(D19), 23631–23650, 1996. Magi, B. I. and Hobbs, P. V.: Effects of humidity on aerosols in southern Africa during the biomass burning season, J. Geophys. Res., 108(D13), 8495, doi:10.1029/2002JD002144, 2003. Magi, B. I., Hobbs, P. V., Schmid, B., and Redemann, J.: Vertical profiles of light scattering, light absorption and single-scattering albedo during the dry, biomass burning season in southern Africa and comparisons of in-situ and remote sensing measurements of aerosol optical depth, J. Geophys. Res., 108(D13), 8504, doi:10.1029/2002JD002361, 2003. Magi, B. I.: Optical Properties and Radiative Forcing of Southern African Biomass Burning Aerosol, Ph.D. thesis, Univ. of Washington, Seattle, 180~pp., 2006. Magi, B. I., Fu, Q., Redemann, J., and Schmid, B.: Using aircraft measurements to estimate the magnitude and uncertainty of the shortwave direct radiative forcing of southern African biomass burning aerosol, J. Geophys. Res., 113, D05213, doi:10.1029/2007JD009258, 2008. Magi, B. I., Ginoux, P. A., Ming, Y., and Ramaswamy, V.: Evaluation of tropical and extratropical Southern Hemisphere African aerosol properties simulated by a climate model, J. Geophys. Res., 114, D14204, doi:10.1029/2008JD011128, 2009. Matichuk, R. I., Colarco, P. R., Smith, J. A., and Toon, O. B.: Modeling the transport and optical properties of smoke aerosols from African savanna fires during the Southern African Regional Science Initiative campaign (SAFARI 2000), J. Geophys. Res., 112, D08203, doi:10.1029/2006JD007528, 2007. Mätzler, C., MATLAB Functions for Mie Scattering and Absorption, Institut für Angewandte Physik, Research Report No. 2002-08, Bern, Switzerland, 2002. Meehl, G. A., Stocker, T. F., Collins, W. D., Friedlingstein, P., Gaye, A. T., Gregory, J. M., Kitoh, A., Knutti, R., Murphy, J. M., Noda, A., Raper, S. C. B., Watterson, I. G., Weaver, A. J., and Zhao, Z.-C.: Global Climate Projections, in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited bY: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2007. Piketh, S. J., Annegarn, H. J., and Tyson, P. D.: Lower tropospheric aerosol loadings over South Africa: The relative contribution of aeolian dust, industrial emissions, and biomass burning, J. Geophys. Res., 104(D1), 1597–1607, 1999. Posfai, M., Simonics, R., Li, J., Hobbs, P. V., and Buseck, P. R.: Individual aerosol particles from biomass burning in southern Africa: 1. Compositions and size distributions of carbonaceous particles, J. Geophys. Res., 108(D13), 8483, doi:10.1029/2002JD002291, 2003. Ruellan, S., Cachier, H., Gaudichet, A., Masclet, P., and Lacaux, J.: Airborne aerosols over central Africa during the Experiment for Regional Sources and Sinks of Oxidants (EXPRESSO), J. Geophys. Res., 104(D23), 30673–30690, 1999. Sinha, P., Hobbs, P. V., Yokelson, R. J., Bertschi, I. T., Blake, D. R., Simpson, I. J., Gao, S., Kirchstetter, T. W., and Novakov, T.: Emissions of trace gases and particles from savanna fires in southern Africa, J. Geophys. Res., 108(D13), 8487, doi:10.1029/2002JD002325, 2003a. Sinha, P., Hobbs, P. V., Yokelson, R. J., Blake, D. R., Gao, S., and Kirchstetter, T. W.: Distributions of trace gases and aerosols during the dry biomass burning season in southern Africa, J. Geophys. Res., $108$(D17), 4536, doi:10.1029/2003JD003691, 2003b. Stier, P., Feichter, J., Kinne, S., Kloster, S., Vignati, E., Wilson, J., Ganzeveld, L., Tegen, I., Werner, M., Balkanski, Y., Schulz, M., Boucher, O., Minikin, A., and Petzold, A.: The aerosol-climate model ECHAM5-HAM, Atmos. Chem. Phys., 5, 1125–1156, 2005. Sun, H., Biedermann, L., and Bond, T. C.: Color of brown carbon: A model for ultraviolet and visible light absorption by organic carbon aerosol, Geophys. Res. Lett., 34, L17813, doi:10.1029/2007GL029797, 2007. Swap, R. J., Annegarn, H. J., Suttles, J. T., King, M. D., Platnick, S., Privette, J. L., and Scholes, R. J.: Africa burning: A thematic analysis of the Southern African Regional Science Initiative (SAFARI 2000), J. Geophys. Res., 108(D13), 8465, doi:10.1029/2003JD003747, 2003. Tang, I. N. and Munkelwitz, H. R.: Water activities, densities, and refractive indices of aqueous sulfates and sodium nitrate droplets of atmospheric importance, J. Geophys. Res., 99(D9), 18801–18808, 1994. Tripathi, B. D., Chaturvedi, S. S., and Tripathi, R. D.: Seasonal Variation in Ambient Air Concentration of Nitrate and Sulfate Aerosols in a Tropical City, Varanasi, Atmos. Environ., 30(15), 2773–2778, 1996. Turpin, B. J. and Lim, H. J.: Species contributions to PM2.5 mass concentrations: Revisiting common assumptions for estimating organic mass, Aerosol Sci. and Tech., 35, 602–610, 2001. White, W. H.: The chemical composition of fine particles, Visibility: Existing and Historical Conditions – Causes and Effects, edited by: Trijonis, J. C., US Nat. Acid Precipitation Assess. Prog., Washington DC, 90–94, 1990. Wild, M.: Short-wave and long-wave surface radiation budgets in GCMs: a review based on the IPCC-AR4/CMIP3 models, Tellus, 60A, 932–945, 2008.