<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "https://jats.nlm.nih.gov/nlm-dtd/publishing/3.0/journalpublishing3.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="3.0" xml:lang="en">
<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACP</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACP</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Atmos. Chem. Phys.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-13-12389-2013</article-id>
<title-group>
<article-title>Size-resolved measurements of brown carbon in water and methanol extracts and estimates of their contribution to ambient fine-particle light absorption</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Liu</surname>
<given-names>J.</given-names>
<ext-link>https://orcid.org/0000-0001-7238-593X</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Bergin</surname>
<given-names>M.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Guo</surname>
<given-names>H.</given-names>
<ext-link>https://orcid.org/0000-0003-0487-3610</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>King</surname>
<given-names>L.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kotra</surname>
<given-names>N.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Edgerton</surname>
<given-names>E.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Weber</surname>
<given-names>R. J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>School of Civil &amp; Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Atmospheric Research and Analysis, Inc, Cary, N.C., USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>19</day>
<month>12</month>
<year>2013</year>
</pub-date>
<volume>13</volume>
<issue>24</issue>
<fpage>12389</fpage>
<lpage>12404</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2013 J. Liu et al.</copyright-statement>
<copyright-year>2013</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/3.0/">https://creativecommons.org/licenses/by/3.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://acp.copernicus.org/articles/13/12389/2013/acp-13-12389-2013.html">This article is available from https://acp.copernicus.org/articles/13/12389/2013/acp-13-12389-2013.html</self-uri>
<self-uri xlink:href="https://acp.copernicus.org/articles/13/12389/2013/acp-13-12389-2013.pdf">The full text article is available as a PDF file from https://acp.copernicus.org/articles/13/12389/2013/acp-13-12389-2013.pdf</self-uri>
<abstract>
<p>Light absorbing organic carbon, often called brown carbon, has the potential
to significantly contribute to the visible light-absorption budget,
particularly at shorter wavelengths. Currently, the relative contributions
of particulate brown carbon to light absorption, as well as the sources of
brown carbon, are poorly understood. With this in mind size-resolved direct
measurements of brown carbon were made at both urban (Atlanta), and rural
(Yorkville) sites in Georgia. Measurements in Atlanta were made at both a
representative urban site and a road-side site adjacent to a main highway.
Fine particle absorption was measured with a multi-angle absorption
photometer (MAAP) and seven-wavelength Aethalometer, and brown carbon
absorption was estimated based on Mie calculations using direct size-resolved
measurements of chromophores in solvents. Size-resolved samples were
collected using a cascade impactor and analyzed for water-soluble organic
carbon (WSOC), organic and elemental carbon (OC and EC), and solution light-absorption spectra of water and methanol extracts. Methanol extracts were
more light-absorbing than water extracts for all size ranges and
wavelengths. Absorption refractive indices of the organic extracts were
calculated from solution measurements for a range of wavelengths and used
with Mie theory to predict the light absorption by fine particles comprised
of these components, under the assumption that brown carbon and other
aerosol components were externally mixed. For all three sites, chromophores
were predominately in the accumulation mode with an aerodynamic mean
diameter of 0.5 μm, an optically effective size range resulting in
predicted particle light absorption being a factor of 2 higher than bulk
solution absorption. Mie-predicted brown carbon absorption at 350 nm
contributed a significant fraction (20 to 40%) relative to total light
absorption, with the highest contributions at the rural site where organic to
elemental carbon ratios were highest. Brown carbon absorption, however, was
highest by the roadside site due to vehicle emissions. The direct
size-resolved measurement of brown carbon in solution definitively shows
that it is present and optically important in the near-UV range in both a
rural and urban environment during the summer when biomass burning emissions are
low. These results allow estimates of brown carbon aerosol absorption from
direct measurements of chromophores in aerosol extracts.</p>
</abstract>
<counts><page-count count="16"/></counts>
</article-meta>
</front>
<body/>
<back>
<ref-list>
<title>References</title>
<ref id="ref1">
<label>1</label><mixed-citation publication-type="other" xlink:type="simple">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.</mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple">Andreae, M. O. and Gelencsér, A.: Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols, Atmos. Chem. Phys., 6, 3131–3148, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-6-3131-2006&quot;&gt;https://doi.org/10.5194/acp-6-3131-2006&lt;/a&gt;, 2006.</mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple">Bahadur, R., Praveen, P. S., Xu, Y. Y., and Ramanathan, V.: Solar absorption by elemental and brown carbon determined from spectral observations, P. Natl. Acad. Sci. USA, 109, 17366–17371, 2012.</mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple">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, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-8-6665-2008&quot;&gt;https://doi.org/10.5194/acp-8-6665-2008&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple">Bateman, A. P., Nizkorodov, S. A., Laskin, J., and Laskin, A.: Photolytic processing of secondary organic aerosols dissolved in cloud droplets, Phys. Chem. Chem. Phys., 13, 12199–12212, 2011.</mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple">Bohren, C. F. and Hoffman, D. R.: Absorption and Scattering of Light by Small Particles, John Wilely and Sons Inc, New York, 1998.</mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple">Bond, T. C.: Spectral dependence of visible light absorption by carbonaceous particles emitted from coal combustion, Geophys. Res. Lett., 28, 4075–4078, 2001.</mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple">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, &lt;a href=&quot;http://dx.doi.org/10.1029/2006JD007315&quot;&gt;https://doi.org/10.1029/2006JD007315&lt;/a&gt;, 2006.</mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple">Bond, T. C., Doherty, S. J., Fahey, D. W., Forster, P. M., Berntsen, T., DeAngelo, B. J., Flanner, M. G., Ghan, S., Kärcher, B., Koch, D., Kinne, S., Kondo, Y., Quinn, P. K., Sarofim, M. C., Schultz, M. G., Schulz, M., Venkataraman, C., Zhang, H., Zhang, S., Bellouin, N., Guttikunda, S. K., Hopke, P. K., Jacobson, M. Z., Kaiser, J. W., Klimont, Z., Lohmann, U., Schwarz, J. P., Shindell, D., Storelvmo, T., Warren, S. G., and Zender, C. S.: Bounding the role of black carbon in the climate system: A scientific assessment, J. Geophys. Res., 118, 5380–5552, &lt;a href=&quot;http://dx.doi.org/10.1002/jgrd.50171&quot;&gt;https://doi.org/10.1002/jgrd.50171&lt;/a&gt;, 2013.</mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple">Bones, D. L., Henricksen, D. K., Mang, S. A., Gonsior, M., Bateman, A. P., Nguyen, T. B., 25 Cooper, W. J., and Nizkorodov, S. A.: Appearance of strong absorbers and fluorophores in limonene-O&lt;sub&gt;3&lt;/sub&gt; secondary organic aerosol due to NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; -mediated chemical aging over long time scales, J. Geophys. Res., 115, D05203, &lt;a href=&quot;http://dx.doi.org/10.1029/2009JD012864&quot;&gt;https://doi.org/10.1029/2009JD012864&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple">Cappa, C. D., Onasch, T. B., Massoli, P., Worsnop, D. R., Bates, T. S., Cross, E. S., Davidovits, P., Hakala, J., Hayden, K. L., Job son, B. T., Kolesar, K. R., Lack, D. A., Lerner, B. M., Li, S. M., Mellon, D., Nuaaman, I., Olfert, J. S., Petaja, T., Quinn, P. K., Song, C., Subramanian, R., Williams, E. J., and Zaveri, R. A.: Radiative Absorption Enhancements Due to the Mixing State of Atmospheric Black Carbon, Science, 337, 1078–1081, 2012.</mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple">Carrico, C. M., Bergin, M. H., Xu, J., Baumann, K., and Maring, H.: Urban aerosol radiative properties: Measurement during the 1999 Atlanta Supersite Experiment, J. Geophys. Res., 108, 8422, &lt;a href=&quot;http://dx.doi.org/10.1029/2001JD001222&quot;&gt;https://doi.org/10.1029/2001JD001222&lt;/a&gt;, 2003.</mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple">Chakrabarty, R. K., Moosmüller, H., Chen, L.-W. A., Lewis, K., Arnott, W. P., Mazzoleni, C., Dubey, M. K., Wold, C. E., Hao, W. M., and Kreidenweis, S. M.: Brown carbon in tar balls from smoldering biomass combustion, Atmos. Chem. Phys., 10, 6363–6370, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-10-6363-2010&quot;&gt;https://doi.org/10.5194/acp-10-6363-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple">Chang, J. L. and Thompson, J. E.: Characterization of colored products formed during irradiation of aqueous solutions containing H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; and phenolic compounds, Atmos. Environ., 44, 541–551, 2010.</mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple">Chen, Y. and Bond, T. C.: Light absorption by organic carbon from wood combustion, Atmos. Chem. Phys., 10, 1773–1787, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-10-1773-2010&quot;&gt;https://doi.org/10.5194/acp-10-1773-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple">Chow, J. C., Watson, J. G., Lowenthal, D. H., and Magliano, K. L.: Size-resolved aerosol chemical concentrations at rural and urban sites in Central California, USA, Atmos. Res., 90, 243–252, 2008.</mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple">Chung, C. E., Ramanathan, V., and Decremer, D.: Observationally constrained estimates of carbonaceous aerosol radiative forcing, P. Natl. Acad. Sci. USA, 109, 11624–11629, 2012.</mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple">De Haan, D. O., Corrigan, A. L., Smith, K.W., Stroik, D. R., Turley, J. J., Lee, F. E., Tolbert, M. A., Jimenez, J. L., Cordova, K. E., and Ferrell, G. R.: Secondary organic aerosol-forming reactions of glyoxal with amino acids, Environ. Sci. Technol., 43, 2818–2824, 2009.</mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple">Dinar, E., Riziq, A. A., Spindler, C., Erlick, C., Kiss, G., and Rudich, Y.: The complex refractive index of atmospheric and model humic-like substances (HULIS) retrieved by a cavity ring down aerosol spectrometer (CRD-AS), Faraday Discuss., 137, 279–295, 2008.</mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple">Duarte, R., Pio, C. A., and Duarte, A. C.: Spectroscopic study of the water-soluble organic matter isolated from atmospheric aerosols collected under different atmospheric conditions, Anal. Chim. Acta, 530, 7–14, 2005.</mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple">Eatough, D. J., Wadsworth, A., Eatough, D. A., Crawford, J. W., Hansen, L. D., and Lewis, E. A.: A multiple-system, multichannel diffusion denuder sampler for the determination of fine-particulate organic material in the atmosphere, Atmos. Environ. A-Gen., 27, 1213–1219, 1993.</mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple">Feng, Y., Ramanathan, V., and Kotamarthi, V. R.: Brown carbon: a significant atmospheric absorber of solar radiation?, Atmos. Chem. Phys., 13, 8607–8621, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-13-8607-2013&quot;&gt;https://doi.org/10.5194/acp-13-8607-2013&lt;/a&gt;, 2013.</mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple">Fuzzi, S., Andreae, M. O., Huebert, B. J., Kulmala, M., Bond, T. C., Boy, M., Doherty, S. J., Guenther, A., Kanakidou, M., Kawamura, K., Kerminen, V.-M., Lohmann, U., Russell, L. M., and Pöschl, U.: Critical assessment of the current state of scientific knowledge, terminology, and research needs concerning the role of organic aerosols in the atmosphere, climate, and global change, Atmos. Chem. Phys., 6, 2017–2038, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-6-2017-2006&quot;&gt;https://doi.org/10.5194/acp-6-2017-2006&lt;/a&gt;, 2006.</mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple">Hansen, D. A., Edgerton, E. S., Hartsell, B., and Jansen, J., Air quality measurements for the aerosol research and inhalation epidemiology study. J. Air Waste Manage., 56, 1445–1458, 2006.</mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple">Hecobian, A., Zhang, X., Zheng, M., Frank, N., Edgerton, E. S., and Weber, R. J.: Water-Soluble Organic Aerosol material and the light-absorption characteristics of aqueous extracts measured over the Southeastern United States, Atmos. Chem. Phys., 10, 5965–5977, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-10-5965-2010&quot;&gt;https://doi.org/10.5194/acp-10-5965-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple">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, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-6-3563-2006&quot;&gt;https://doi.org/10.5194/acp-6-3563-2006&lt;/a&gt;, 2006.</mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple">Huang, X. F., Yu, J. Z., He, L. Y., and Hu, M.: Size distribution characteristics of elemental carbon emitted from Chinese vehicles: results of a tunnel study and atmospheric implications, Environ. Sci. Technol., 40, 5355–5360, 2006.</mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple">IPCC: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment, Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK, and New York, NY, USA, 996 pp., 2007.</mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple">Jacobson, M. Z.: Isolating nitrated and aromatic aerosols and nitrated aromatic gases as sources of ultraviolet light absorption, J. Geophys. Res.-Atmos., 104, 3527–3542, 1999.</mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple">Jung, J., Kim, Y. J., Lee, K. Y., Cayetano, M. G., Batmunkh, T., Koo, J.-H., and Kim, J.: Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008, Atmos. Chem. Phys., 10, 5391–5408, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-10-5391-2010&quot;&gt;https://doi.org/10.5194/acp-10-5391-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple">Kieber, R. J., Whitehead, R. F., Reid, S. N., Willey, J. D., and Seaton, P. J.: Chromophoric dissolved organic matter (CDOM) in rainwater, southeastern North Carolina, USA, J. Atmos. Chem., 54, 21–41, 2006.</mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple">Kirchstetter, T. W. and Thatcher, T. L.: Contribution of organic carbon to wood smoke particulate matter absorption of solar radiation, Atmos. Chem. Phys., 12, 6067–6072, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-12-6067-2012&quot;&gt;https://doi.org/10.5194/acp-12-6067-2012&lt;/a&gt;, 2012.</mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple">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.-Atmos., 109, D21208, &lt;a href=&quot;http://dx.doi.org/10.1029/2004JD004999&quot;&gt;https://doi.org/10.1029/2004JD004999&lt;/a&gt;, 2004.</mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple">Lack, D. A. and Cappa, C. D.: Impact of brown and clear carbon on light absorption enhancement, single scatter albedo and absorption wavelength dependence of black carbon, Atmos. Chem. Phys., 10, 4207–4220, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-10-4207-2010&quot;&gt;https://doi.org/10.5194/acp-10-4207-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple">Lack, D. A., Langridge, J. M., Bahreini, R., Brock, C. A., Middlebrook, A. M., and Schwarz, J. P.: Brown Carbon and Internal Mixing in Biomass Burning Particles, P. Natl. Acad. Sci. USA, 109, 14802–14807, &lt;a href=&quot;http://dx.doi.org/10.1073/pnas.1206575109&quot;&gt;https://doi.org/10.1073/pnas.1206575109&lt;/a&gt;, 2012.</mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple">Lan, Z. J., Chen, D. L., Li, X. A., Huang, X. F., He, L. Y., Deng, Y. G., Feng, N., and Hu, M.: Modal characteristics of carbonaceous aerosol size distribution in an urban atmosphere of South China, Atmos. Res., 100, 51–60, 2011.</mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple">Limbeck, A., Kulmala, M., and Puxbaum, H.: Secondary organic aerosol formation in the atmosphere via heterogeneous reaction of gaseous isoprene on acidic particles, Geophys. Res. Lett., 30, 1996, &lt;a href=&quot;http://dx.doi.org/10.1029/2003GL017738&quot;&gt;https://doi.org/10.1029/2003GL017738&lt;/a&gt;, 2003.</mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple">Lukacs, H., Gelencser, A., Hammer, S., Puxbaum, H., Pio, C., Legrand, M., Kasper-Giebl, A., Handler, M., Limbeck, A., Simpson, D., and Preunkert, S.: Seasonal trends and possible sources of brown carbon based on 2-year aerosol measurements at six sites in Europe, J. Geophys. Res., 112, D23S18, &lt;a href=&quot;http://dx.doi.org/10.1029/2006JD008151&quot;&gt;https://doi.org/10.1029/2006JD008151&lt;/a&gt;, 2007.</mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple">Moosmuller, H., Chakrabarty, R. K., and Arnott, W. P.: Aerosol light absorption and its measurement: a review, J. Quant. Spectrosc. Ra., 110, 844–878, 2009.</mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple">Nakayama, T., Matsumi, Y., Sato, K., Imamura, T., Yamazaki, A., and Uchiyama, A.: Laboratory studies on optical properties of secondary organic aerosols generated during the photooxidation of toluene and the ozonolysis of alpha-pinene, J. Geophys. Res.-Atmos., 115, D24204, &lt;a href=&quot;http://dx.doi.org/10.1029/2010JD014387&quot;&gt;https://doi.org/10.1029/2010JD014387&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple">Nakayama, T., Sato, K., Matsumi, Y., Imamura, T., Yamazaki, A., and Uchiyama, A.: Wavelength and NO&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; dependent complex refractive index of SOAs generated from the photooxidation of toluene, Atmos. Chem. Phys., 13, 531–545, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-13-531-2013&quot;&gt;https://doi.org/10.5194/acp-13-531-2013&lt;/a&gt;, 2013.</mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple">Nguyen, T. B., Lee, P. B., Updyke, K. M., Bones, D. L., Laskin, J., Laskin, A., and Nizkorodov, S. A.: Formation of nitrogen and sulfur-containing light-absorbing compounds accelerated by evaporation of water from secondary organic aerosols, J. Geophys. Res., 117, D01207, &lt;a href=&quot;http://dx.doi.org/10.1029/2011JD016944&quot;&gt;https://doi.org/10.1029/2011JD016944&lt;/a&gt;, 2012.</mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple">NIOSH: Elemental Carbon (Diesel Particulate): Method 5040, in: NIOSH Manual of Analytical Methods, edited by: Eller, P. M. and Cassinelli, M. E., National Institute for Occupational Safety and Health, Cincinnati, USA, 1996.</mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple">Park, R. J., Kim, M. J., Jeong, J. I., Youn, D., and Kim, S.: A contribution of brown carbonaerosol to the aerosol light absorption and its radiative forcing in East Asia, Atmos. Environ., 44, 1414–1421, &lt;a href=&quot;http://dx.doi.org/10.1016/j.atmosenv.2010.01.042&quot;&gt;https://doi.org/10.1016/j.atmosenv.2010.01.042&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple">Petzold, A. and Schönlinner, M.: Multi-angle absorption photometry – a new method for the measurement of aerosol light absorption and atmospheric black carbon, J. Aerosol Sci., 35, 421–441, 2004.</mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple">Qin, Y. and Mitchell, R. M.: Characterisation of episodic aerosol types over the Australian continent, Atmos. Chem. Phys., 9, 1943–1956, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-9-1943-2009&quot;&gt;https://doi.org/10.5194/acp-9-1943-2009&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple">Rizzo, L. V., Correia, A. L., Artaxo, P., Procópio, A. S., and Andreae, M. O.: Spectral dependence of aerosol light absorption over the Amazon Basin, Atmos. Chem. Phys., 11, 8899–8912, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-11-8899-2011&quot;&gt;https://doi.org/10.5194/acp-11-8899-2011&lt;/a&gt;, 2011.</mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple">Sandradewi, J., Prév\^t, A. S. H., Alfarra, M. R., Szidat, S., Wehrli, M. N., Ruff, M., Weimer, S., Lanz, V. A., Weingartner, E., Perron, N., Caseiro, A., Kasper-Giebl, A., Puxbaum, H., Wacker, L., and Baltensperger, U.: Comparison of several wood smoke markers and source apportionment methods for wood burning particulate mass, Atmos. Chem. Phys. Discuss., 8, 8091–8118, &lt;a href=&quot;http://dx.doi.org/10.5194/acpd-8-8091-2008&quot;&gt;https://doi.org/10.5194/acpd-8-8091-2008&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref49">
<label>49</label><mixed-citation publication-type="other" xlink:type="simple">Sareen, N., Schwier, A. N., Shapiro, E. L., Mitroo, D., and McNeill, V. F.: Secondary organic material formed by methylglyoxal in aqueous aerosol mimics, Atmos. Chem. Phys., 10, 997–1016, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-10-997-2010&quot;&gt;https://doi.org/10.5194/acp-10-997-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref50">
<label>50</label><mixed-citation publication-type="other" xlink:type="simple">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, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-9-2289-2009&quot;&gt;https://doi.org/10.5194/acp-9-2289-2009&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref51">
<label>51</label><mixed-citation publication-type="other" xlink:type="simple">Sokolik, I. N. and Toon, O. B.: Incorporation of mineralogical com- position into models of the radiative properties of mineral aerosol from UV to IR wavelengths, J. Geophys. Res., 104, 9423–9444, 1999.</mixed-citation>
</ref>
<ref id="ref52">
<label>52</label><mixed-citation publication-type="other" xlink:type="simple">Sun, H., Biedermann, L., and Bond, T. C.: The color of brown carbon: A model for ultraviolet and visible light absorption by organic carbon aerosol, Geophys. Res. Lett., 34, L17813, &lt;a href=&quot;http://dx.doi.org/10.1029/2007GL029797&quot;&gt;https://doi.org/10.1029/2007GL029797&lt;/a&gt;, 2007.</mixed-citation>
</ref>
<ref id="ref53">
<label>53</label><mixed-citation publication-type="other" xlink:type="simple">Updyke, K. M., Nguyen, T. B., and Nizkorodov, S. A.: Formation of brown carbon via reactions of ammonia with secondary organic aerosols from biogenic and anthropogenic precursors, Atmos. Environ., 63, 22–31, 2012.</mixed-citation>
</ref>
<ref id="ref54">
<label>54</label><mixed-citation publication-type="other" xlink:type="simple">Weingartner, E., Saathoff, H., Schnaiter, M., Streit, N., Bitnar, B., and Baltensperger, U.: Absorption of light by soot particles: determination of the absorption coefficient by means of aethalometers, J. Aerosol Sci., 34, 1445–1463, 2003.</mixed-citation>
</ref>
<ref id="ref55">
<label>55</label><mixed-citation publication-type="other" xlink:type="simple">Yan, F., Winijkul, E., Jung, S., Bond, T. C., and Streets, D. G.: Global emission projections of particulate matter (PM): I. Exhaust emissions from on-road vehicles, Atmos. Environ., 45, 4830–4844, 2011.</mixed-citation>
</ref>
<ref id="ref56">
<label>56</label><mixed-citation publication-type="other" xlink:type="simple">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, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-9-2035-2009&quot;&gt;https://doi.org/10.5194/acp-9-2035-2009&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref57">
<label>57</label><mixed-citation publication-type="other" xlink:type="simple">Zhang, X., Lin, Y.-H., Surratt, J. D., Zotter, P., Prévôt, A. H. S., and Weber, R. J.: Light-absorbing soluble organic aerosol in Los Angeles and Atlanta: A contrast in secondary organic aerosol, Geophys. Res. Lett., 38, L21810, &lt;a href=&quot;http://dx.doi.org/10.1029/2011GL049385&quot;&gt;https://doi.org/10.1029/2011GL049385&lt;/a&gt;, 2011.</mixed-citation>
</ref>
<ref id="ref58">
<label>58</label><mixed-citation publication-type="other" xlink:type="simple">Zhang, X. L., Lin, Y. H., Surratt, J. D., and Weber, R. J.: Sources, composition and absorption Angström exponent of light-absorbing organic components in aerosol extracts from the Los Angeles Basin, Environ. Sci. Technol., 47, 3685–3693, &lt;a href=&quot;http://dx.doi.org/10.1021/es305047b&quot;&gt;https://doi.org/10.1021/es305047b&lt;/a&gt;, 2013.</mixed-citation>
</ref>
</ref-list>
</back>
</article>