Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 10 1 2010 10.5194/acpd-10-785-2010 http://www.atmos-chem-phys-discuss.net/10/785/2010/ http://www.atmos-chem-phys-discuss.net/10/785/2010/acpd-10-785-2010.html http://www.atmos-chem-phys-discuss.net/10/785/2010/acpd-10-785-2010.pdf 785 819 2010-01-15 Impact of brown and clear carbon on light absorption enhancement, single scatter albedo and absorption wavelength dependence of black carbon D. A. Lack daniel.lack@noaa.gov C. D. Cappa NOAA Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, 80304, CO, USA Cooperative Institute for Research in Environmental Sciences, University of Colorado, 216 UCB, Boulder, 80309, CO, USA Department of Civil and Environmental Engineering, University of California, Davis, California, USA The presence of clear coatings on atmospheric black carbon (BC) particles is known to enhance the magnitude of light absorption by the BC cores. Based on calculations using core/shell Mie theory, we demonstrate the enhancement of light absorption (<i>E</i>_Abs) by atmospheric black carbon (BC) when coated in mildly absorbing material (C_Brown) is reduced, relative to the enhancement by non-absorbing coatings (C_Clear). This reduction, sensitive to C_Brown shell thickness and imaginary refractive index (RI), can be up to 50% for 400 nm radiation and 25% averaged across the visible radiation spectrum for reasonable core/shell diameters. The enhanced direct radiative forcing possible due to the enhancement effect of C_Clear is therefore reduced if the coating is absorbing. Additionally, the need to explicitly treat BC as an internal, as opposed to external, mixture with C_Brown is shown to be important to the calculated single scatter albedo only whensub models treat BC as large spherical cores (>50 nm). For smaller BC cores (or fractal agglomerates) consideration of the BC and C_Brown as an external mixture leads to relatively small errors in the particle single scatter albedo of <0.03. It is often assumed that observation of an absorption Angstrom exponent (AAE) >1 indicates non-BC absorption. Here, it is shown that BC cores coated in C_Clearcan reasonably have an AAE of up to 1.6, a result that complicates the attribution of observed light absorption to C_Brown within ambient particles. However, an AAE<1.6 does not exclude the possibility of C_Brown, rather C_Brown cannot be confidently assigned unless AAE>1.6. Comparison of these results to some ambient AAE data shows that large-scale attribution of C_Brown is a challenging task using current in-situ measurement methods. We suggest that coincident measurements of particle core and shell sizes along with the AAE may be necessary to distinguish absorbing and non-absorbing OC. Alexander,~D T L., Crozier,~P A., and Anderson,~J R.: Brown carbon spheres in east asian outflow and their optical properties, Science, 321, 833–836, 2008. Andreae,~M O. and Gelencsér,~A.: Black carbon or brown carbon? The nature of light absorbing carbonaceous aerosols, Atmos. Chem. Phys., 6, 3131–3148, 2006. Barnard,~J C., Volkamer,~R., and Kassianov,~E I.: Estimation of the mass absorption cross section of the organic carbon component of aerosols in the Mexico City Metropolitan Area, Atmos. Chem. Phys., 8, 6665–6679, 2008. Bates,~T S., Quinn,~P K., Coffman,~D J., Johnson,~J E., and Middlebrook,~A M.: Dominance of organic aerosols in the marine boundary layer over the Gulf of Maine during NEAQS 2002 and their role in aerosol light scattering, J. Geophys. Res., 110, D18202, \doi10.1029/2005jd005797, 2005. Bates,~T S., Quinn,~P K., Coffman,~D J., Schulz,~K., Covert,~D S., Johnson,~J E., Williams,~E J., Lerner,~B M., Angevine,~W M., Tucker,~S C., Brewer,~W A., and Stohl,~A.: Boundary layer aerosol chemistry during TexAQS/GoMACCS 2006: Insights into Aerosol Sources and transformation processes, J. Geophys. Res., 113, D00F01, \doi10.1029/2008JD010023, 2008. Bergstrom,~R W., Pilewskie,~P., Russell,~P B., Redemann,~J., Bond,~T C., Quinn,~P K., and Sierau,~B.: Spectral absorption properties of atmospheric aerosols, Atmos. Chem. Phys., 7, 5937–5943, 2007. Bohren,~C F. and Huffman,~D R.: Absorption and Scattering of Light by Small Particles, John Wiley & Sons, Inc, 530 pp., 1983. Bond,~T., Habib,~G., and Bergstrom,~R W.: Limitations in the enhancement of visible light absorption due to mixing state,~J. Geophys. Res., 111, D20211, \doi10.1029/2006JD007315, 2006. Bond,~T C. and Bergstrom,~R W.: Light absorption by carbonaceous particles: an investigative review, Aerosol Sci. Tech., 40, 27–67, 2006. Cappa,~C., Lack,~D., Burkholder,~J., and Ravishankara,~A.: Bias in filter based aerosol light absorption measurements due to organic aerosol loading: evidence from laboratory measurements, Aerosol Sci. Tech., 42, 1022–1032, 2008. Clarke,~A., McNaughton,~C., Kapustin,~V., Shinozuka,~Y., Howell,~S., Dibb,~J., Zhou,~J., Anderson,~B., Brekhovskikh,~V., Turner,~H., and Pinkerton,~M.: Biomass burning and pollution aerosol over North America: organic components and their influence on spectral optical properties and humidification response,~J. Geophys. Res., 112, D12S18, \doi10.1029/2006jd007777, 2007. Favez,~O., Alfaro,~S C., Sciare,~J., Cachier,~H., and Abdelwahab,~M M.: Ambient measurements of light-absorption by agricultural waste burning organic aerosols, J. Aerosol Sci., 40, 613–620, 2009. Fuller,~K A., Malm,~W C., and Kreidenweis,~S M.: Effects of mixing on extinction by carbonaceous particles, J. Geophys. Res., 104, 15941-15954, 1999. Gustafsson,~O., Krusa,~M., Zencak,~Z., Sheesley,~R J., Granat,~L., Engstrom,~E., Praveen,~P S., Rao,~P S P., Leck,~C., and Rodhe,~H.: Brown clouds over South Asia: biomass or fossil fuel combustion? Science, 323, 495–498, \doi10.1126/science.1164857, 2009. Gyawali,~M., Arnott,~W P., Lewis,~K., and Moosmüller,~H.: In situ aerosol optics in Reno, NV, USA during and after the summer 2008 California wildfires and the influence of absorbing and non-absorbing organic coatings on spectral light absorption, Atmos. Chem. Phys., 9, 8007–8015, 2009. Hoffer,~A., Gelencsér,~A., Guyon,~P., Kiss,~G., Schmid,~O., Frank,~G P., Artaxo,~P., and Andreae,~M O.: Optical properties of humic-like substances (HULIS) in biomass-burning aerosols, Atmos. Chem. Phys., 6, 3563–3570, 2006. IPCC: Climate Change 2007: The Physical Science Basis. Contribution of Working Group 1 to the Fourth Assessment Report. Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK and New York, NY USA, 2007. Jacobson,~M Z.: A physically-based treatment of elemental carbon optics: implications for global direct forcing of aerosols, Geophys. Res. Lett., 27(2), 217–220, \doi10.1029/1999gl010968, 2000. Jacobson,~M Z.: Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature, 409, 695–697, 2001. Kinne,~S., Lohmann,~U., Feichter,~J., Schulz,~M., Timmreck,~C., Ghan,~S., Easter,~R., Chin,~M., Ginoux,~P., Takemura,~T., Tegen,~I., Koch,~D., Herzog,~M., Penner,~J., Pitari,~G., Holben,~B., Eck,~T., Smirnov,~A., Dubovik,~O., Slutsker,~I., Tanre,~D., Torres,~O., Mishchenko,~M., Geogdzhayev,~I., Chu,~D A., and Kaufman,~Y.: Monthly averages of aerosol properties: a~global comparison among models, satellite data, and AERONET ground data,~J. Geophys. Res., 108, \doi10.1029/2001jd001253, 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, D21208, doi:10.1029/2004JD004999, 2004. Kondo,~Y., Sahu,~L., Kuwata,~M., Miyazaki,~Y., Takegawa,~N., Moteki, N., Imaru,~J., Han,~N S., Nakayama,~T., Kim-Oanh,~N T., Hu,~M., Kim,~Y J., and Kita,~K.: Stabilization of the mass absorption cross section of black carbon for filter-based absorption photometry by the use of a~heated inlet, Aerosol Sci. Tech., 43, 8, \doi10.1080/02786820902889879, 2009. Lack,~D A., Cappa,~C D., Covert,~D S., Baynard,~T., Massoli,~P., Sierau,~B., Bates,~T S., Quinn,~P K., Lovejoy,~E R., and Ravishankara,~A R.: Bias in filter based aerosol light absorption measurements due to organic aerosol loading: evidence from ambient measurements, Aerosol Sci. Tech., 42, 1033–1041, 2008. Lack,~D A., Cappa,~C D., Cross,~E S., Massoli,~P., Ahern,~A T., Davidovits,~P., and Onasch,~T B.: Absorption enhancement of coated absorbing aerosols: validation of the photo-acoustic technique for measuring the enhancement, Aerosol Sci. Tech., 43, 1006–1012, 2009a. Lack,~D A., Quinn,~P K., Massoli,~P., Bates,~T S., Coffman,~D., Covert,~D S., Sierau,~B., Tucker,~S., Baynard,~T., Lovejoy,~E R., Murphy,~D M., and Ravishankara,~A R.: Relative humidity dependence of light absorption by mineral dust after long-range atmospheric transport from the Sahara, Geophys. Res. Lett., 36, L24805, doi:10.1029/2009GL041002, 2009b. Moteki,~N., Kondo,~Y., Miyazaki,~Y., Takegawa,~N., Komazaki,~Y., Kurata,~G., Shirai,~T., Blake,~D R., Miyakawa,~T., and Koike,~M.: Evolution of mixing state of black carbon particles: aircraft measurements over the western pacific in March 2004, Geophys. Res. Lett., 34, L11803, \doi10.1029/2006gl028943, 2007. Quinn,~P K., Coffman,~D J., Bates,~T S., Miller,~T L., Johnson,~J E., Welton,~E J., Neususs,~C., Miller,~M., and Sheridan,~P J.: Aerosol optical properties during INDOEX 1999: means, variability, and controlling factors,~J. Geophys. Res., 107(D19), 8020, , \doi10.1029/2000jd000037, 2002. Quinn,~P K., Coffman,~D J., Bates,~T S., Welton,~E J., Covert,~D S., Miller,~T L., Johnson,~J E., Maria,~S., Russell,~L., Arimoto,~R., Carrico,~C M., Rood,~M J., and Anderson,~J.: Aerosol optical properties measured onboard the Ronald~H. Brown during ACE-asia as a~function of aerosol chemical composition and source region,~J. Geophys. Res., 109, D19S01, \doi10.1029/2003jd004010, 2004. Rincon,~A G., Guzman,~M I., Hoffmann,~M R., and Colussi,~A J.: Optical absorptivity versus molecular composition of model organic aerosol matter,~J. Phys. Chem. A, 113(39), 9~pp., 2009. Roden,~C A., Bond,~T C., Conway,~S., and Pinel,~A B O.: Emission factors and real-time optical properties of particles emitted from traditional wood burning cookstoves, Environ. Sci. Technol., 40, 6750–6757, \doi10.1021/es052080i, 2006. Schnaiter,~M., Linke,~M., Möhler,~O., Naumann,~K.-H., Saathoff,~H., Wagner,~R., Schurath,~U., and Wehner,~B.: Absorption amplification of black carbon internally mixed with secondary organic aerosol,~J. Geophys. Res., 110, D19204, \doi10.1029/2005JD006046, 2005. Schnaiter,~M., Gimmler,~M., Llamas,~I., Linke,~C., Jäger,~C., and Mutschke,~H.: Strong spectral dependence of light absorption by organic carbon particles formed by propane combustion, Atmos. Chem. Phys., 6, 2981–2990, 2006. Schwarz,~J P., Gao,~R S., Spackman,~J R., Watts,~L A., Thomson,~D S., Fahey,~D W., Ryerson,~T B., Peischl,~J., Holloway,~J S., Trainer,~M., Frost,~G J., Baynard,~T., Lack,~D A., de Gouw,~J A., Warneke,~C., and Del Negro,~L A.: Measurement of the mixing state, mass, and optical size of individual black carbon particles in urban and biomass burning emissions, Geophys. Res. Lett., 35, L13810, \doi10.1029/2008gl033968, 2008. Schwier,~A N., Shapiro,~E L., Sareen,~N., and McNeill,~V F.: Secondary organic material formed by methylglyoxal in aqueous aerosol mimics – Part 1: Surface tension depression and light-absorbing products, Atmos. Chem. Phys. Discuss., 9, 15541–15565, 2009. Shapiro,~E L., Szprengiel,~J., Sareen,~N., Jen,~C N., Giordano,~M R., and McNeill,~V F.: Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics, Atmos. Chem. Phys., 9, 2289–2300, 2009. Sierau,~B., Covert,~D S., Coffman,~D J., Quinn,~P K., and Bates,~T S.: Aerosol optical properties during the 2004 New England air quality study – intercontinental transport and chemical transformation: Gulf of Maine surface measurements – regional and case studies,~J. Geophys. Res., 111, D23S37, \doi10.1029/2006jd007568, 2006. Sorensen,~C M.: The optics of single particles and fractal aggregates,~J. Aerosol Sci., 31, 952–954, 2000. 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, \doi10.1029/2007gl029797, 2007. van Poppel,~L H., Friedrich,~H., Spinsby,~J., Chung,~S H., Seinfeld,~J H., and Buseck,~P R.: Electron tomography of nanoparticle clusters: implications for atmospheric lifetimes and radiative forcing of soot, Geophys. Res. Lett., 32, L24811, \doi10.1029/2005gl024461, 2005. Yang,~M., Howell,~S G., Zhuang,~J., and Huebert,~B J.: Attribution of aerosol light absorption to black carbon, brown carbon, and dust in China – interpretations of atmospheric measurements during EAST-AIRE, Atmos. Chem. Phys., 9, 2035–2050, 2009. Zhang,~Q., Jimenez,~J L., Canagaratan,~M R., Allan,~J D., Coe,~H., Ulbrich,~I., Alfarra,~M R., Takami,~A., Middlebrook,~A M., Sun,~Y L., Dzepina,~K., Dunlea,~E., Docherty,~K., DeCarlo,~P F., Salcedo,~D., Onasch,~T., Jayne,~J T., Miyoshi,~T., Shimono,~A., Hatakeyama,~S., Takegawa,~N., Kondo,~Y., Schneider,~J., Drewnick,~R., Borrmann,~S., Weimer,~S., Demerjian,~K., Williams,~P I., Bower,~K N., Bahreini,~R., Cottrell,~L., Griffin,~R J., Rautiainen,~J., Sun,~J Y., Zhang,~Y M., and Worsnop,~D R.: Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically-influenced Northern Hemisphere midlatitudes, Geophys. Res. Lett., 34, L13801, \doi10.1029/2007GL029979, 2007. Zhang,~R., Khalizov,~A F., Pagels,~J., Zhang,~D., Xue,~H., and McMurry,~P H.: Variability in morphology, hygroscopicity, and optical properties of soot aerosols during atmospheric processing, P. Natl. Acad. Sci. USA, 105, 10291–10296, 2008.