Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 10 2 2010 10.5194/acpd-10-2445-2010 http://www.atmos-chem-phys-discuss.net/10/2445/2010/ http://www.atmos-chem-phys-discuss.net/10/2445/2010/acpd-10-2445-2010.html http://www.atmos-chem-phys-discuss.net/10/2445/2010/acpd-10-2445-2010.pdf 2445 2502 2010-02-02 Investigation of the sources and processing of organic aerosol over the Central Mexican Plateau from aircraft measurements during MILAGRO P. F. DeCarlo I. M. Ulbrich J. Crounse B. de Foy E. J. Dunlea A. C. Aiken D. Knapp A. J. Weinheimer T. Campos P. O. Wennberg J. L. Jimenez jose.jimenez@colorado.edu Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA Department of Atmospheric and Oceanic Science, University of Colorado, Boulder, CO, USA Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA California Institute of Technology, Pasadena, CA, USA Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, MO, USA National Center for Atmospheric Research, Boulder, CO, USA Organic aerosol (OA) represents approximately half of the submicron aerosol in Mexico City and the Central Mexican Plateau. This study uses the high time resolution measurements performed onboard the NCAR/NSF C-130 aircraft during the MILAGRO/MIRAGE-Mex field campaign in March 2006 to investigate the sources and chemical processing of the OA in this region. An examination of the OA/ΔCO ratio evolution as a function of photochemical age shows distinct behavior in the presence or absence of substantial open biomass burning (BB) influence, with the latter being consistent with other studies in polluted areas. In addition, we present results from Positive Matrix Factorization (PMF) analysis of 12-s High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) OA spectra. Four components were resolved. Three of the components contain substantial organic oxygen and are termed semivolatile oxygenated OA (SV-OOA), low-volatility OOA (LV-OOA), and biomass burning OA (BBOA). A reduced &quot;hydrocarbon-like OA&quot; (HOA) component is also resolved. LV-OOA is highly oxygenated (atomic O/C~1) and is aged organic aerosol linked to regional airmasses, with likely contributions from pollution, biomass burning, and other sources. SV-OOA is strongly correlated with ammonium nitrate, O_x, and the Mexico City Basin. We interpret SV-OOA as secondary OA which is nearly all (&gt;90%) anthropogenic in origin. In the absence of biomass burning it represents the largest fraction of OA over the Mexico City basin, consistent with other studies in this region. BBOA is identified as arising from biomass burning sources due to a strong correlation with HCN, and the elevated contribution of the ion C₂H₄O₂⁺ (<i>m/z</i> 60, a marker for levoglucosan and other primary BB species). WRF-FLEXPART calculated fire impact factors (FIF) show good correlation with BBOA mass concentrations within the basin, but show location offsets in the far field due to model transport errors. This component is small or absent when forest fires are suppressed by precipitation. Since PMF factors represent organic species grouped by chemical similarity, and this study spans a very large and continuous range of OA ages, additional postprocessing is needed to more directly apportion OA amounts to sources, which is done here based on correlations and regressions to key tracers. The postprocessed AMS results are similar to those from an independent source apportionment based on multiple linear regression with gas-phase tracers. During a flight with very high forest fire intensity near the basin OA arising from open BB represents ~66% of the OA mass in the basin and contributes similarly OA mass in the outflow. Aging and SOA formation of BB emissions is estimated to add OA mass equivalent to about ~32–42% of the primary BBOA over several hours to a day. Aiken,~A C., DeCarlo,~P F., and Jimenez,~J L.: Elemental Analysis of Organic Species with Electron Ionization High-Resolution Mass Spectrometry, Anal. Chem., 79(21), 8350-8358, 2007. Aiken,~A C., DeCarlo,~P F., Kroll,~J H., Worsnop,~D R., et al.: O/C and OM/OC ratios of primary, secondary, and ambient organic aerosols with high-resolution time-of-flight aerosol mass spectrometry, Environ. Sci. Technol., 42, 4478–4485, 2008. Aiken,~A C., de Foy,~B., Wiedinmyer,~C., DeCarlo,~P F., Ulbrich,~I M., Wehrli,~M N., Szidat,~S., Prevot,~A S H., Noda,~J., Wacker,~L., Volkamer,~R., Fortner,~E., Wang,~J., Laskin,~A., Shutthanandan,~V., Zheng,~J., Zhang,~R., Paredes-Miranda,~G., Arnott,~W P., Molina,~L T., Sosa,~G., Querol,~X., and Jimenez,~J L.: Mexico City aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) – Part~2: Analysis of the biomass burning contribution and the modern carbon fraction, Atmos. Chem. Phys. Discuss., 9, 25915–25981, 2009a. Aiken,~A C., Salcedo,~D., Cubison,~M J., Huffman,~J A., DeCarlo,~P F., Ulbrich,~I M., Docherty,~K S., Sueper,~D., Kimmel,~J R., Worsnop,~D R., Trimborn,~A., Northway,~M., Stone,~E A., Schauer,~J J., Volkamer,~R M., Fortner,~E., de Foy,~B., Wang,~J., Laskin,~A., Shutthanandan,~V., Zheng,~J., Zhang,~R., Gaffney,~J., Marley,~N A., Paredes-Miranda,~G., Arnott,~W P., Molina,~L T., Sosa,~G., and Jimenez,~J L.: Mexico City aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) – Part~1: Fine particle composition and organic source apportionment, Atmos. Chem. Phys., 9, 6633–6653, 2009b. Alfarra,~M R., Prevot,~A S H., Szidat,~S., Sandradewi,~J., et al.: Identification of the mass spectral signature of organic aerosols from wood burning emissions, Environ. Sci. Technol., 41, 5770–5777 \doi5710.1021/es062289b, 2007. Allan,~J D., Jimenez,~J L., Williams,~P I., Alfarra,~M R., et al.: Quantitative sampling using an aerodyne aerosol mass spectrometer: 1. techniques of data interpretation and error analysis, J. Geophys. Res.-Atmos., 108, 4090, \doi4010.1029/2002JD002358, 2003. Allan,~J D., Delia,~A E., Coe,~H., Bower,~K N., et al.: A~generalised method for the extraction of chemically resolved mass spectra from aerodyne aerosol mass spectrometer data, J. Aerosol. Sci., 35, 909–922, 2004. Allan,~J D., Williams,~P I., Morgan,~W T., Martin,~C L., Flynn,~M J., Lee,~J., Nemitz,~E., Phillips,~G J., Gallagher,~M W., and Coe,~H.: Contributions from transport, solid fuel burning and cooking to primary organic aerosols in two UK cities, Atmos. Chem. Phys. Discuss., 9, 19103–19157, 2009. %%%%ok Andreae,~M O., Andreae,~T W., Annegarn,~H., Beer,~J., et al.: Airborne studies of aerosol emissions from savanna fires in Southern Africa: 2 Aerosol chemical composition, J. Geophys. Res.-Atmos., 103, 32119–32128, 1998. Babbitt,~R E., Ward,~D E., Susott,~R S., Artaxo,~P., et al.: A~comparison of concurrent airborne and ground based emissions generated from biomass burning in the Amazon Basin, SCAR-B Proceedings, Transtech Editorial, Sao José dos Campos, Brazil 1997, 23–26. Cappa, C. D. and Jimenez, J. L.: Quantitative estimates of the volatility of ambient organic aerosol, Atmos. Chem. Phys. Discuss., 10, 1901–1938, 2010. Chow,~J C., Watson,~J G., Edgerton,~S A., and Vega,~E.: Chemical composition of \chemPM_2.5 and \chemPM_10 in Mexico City during winter 1997, Sci. Total Environ., 287, 177–201, 2002. Crounse,~J D., DeCarlo,~P F., Blake,~D R., Emmons,~L K., Campos,~T L., Apel,~E C., Clarke,~A D., Weinheimer,~A J., McCabe,~D C., Yokelson,~R J., Jimenez,~J L., and Wennberg,~P O.: Biomass burning and urban air pollution over the Central Mexican Plateau, Atmos. Chem. Phys., 9, 4929–4944, 2009. de Foy,~B., Fast,~J D., Paech,~S J., Phillips,~D., Walters,~J T., Coulter,~R L., Martin,~T J., Pekour,~M S., Shaw,~W J., Kastendeuch,~P P., Marley,~N A., Retama,~A., and Molina,~L T.: Basin-scale wind transport during the MILAGRO field campaign and comparison to climatology using cluster analysis, Atmos. Chem. Phys., 8, 1209–1224, 2008. de Foy, B., Krotkov, N. A., Bei, N., Herndon, S. C., Huey, L. G., Martínez, A.-P., Ruiz-Suárez, L. G., Wood, E. C., Zavala, M., and Molina, L. T.: Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI \chemSO_2 retrievals during the MILAGRO field campaign, Atmos. Chem. Phys., 9, 9599–9617, 2009a. de Foy,~B., Zavala,~M., Bei,~N., and Molina,~L T.: Evaluation of WRF mesoscale simulations and particle trajectory analysis for the MILAGRO field campaign, Atmos. Chem. Phys., 9, 4419–4438, 2009b. de Gouw,~J. and Jimenez,~J L.: Organic aerosols in the earth's atmosphere, Environ. Sci. Technol., 43, 7614–7618, \doi10.1021/Es9006004, 2009. de Gouw,~J A., Brock,~C A., Atlas,~E L., Bates,~T S., et al.: Sources of particulate matter in the Northeastern United States: 1 Direct emissions and secondary formation of organic matter in urban plumes, J. Geophys. Res., 113, D08301, \doi08310.01029/02007JD009243, 2008. de Gouw,~J A., Welsh-Bon,~D., Warneke,~C., Kuster,~W C., Alexander,~L., Baker,~A K., Beyersdorf,~A J., Blake,~D R., Canagaratna,~M., Celada,~A T., Huey,~L G., Junkermann,~W., Onasch,~T B., Salcido,~A., Sjostedt,~S J., Sullivan,~A P., Tanner,~D J., Vargas,~O., Weber,~R J., Worsnop,~D R., Yu,~X Y., and Zaveri,~R.: Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study, Atmos. Chem. Phys., 9, 3425–3442, 2009. DeCarlo,~P F., Kimmel,~J R., Trimborn,~A., Northway,~M J., et al.: Field-deployable, high-resolution, time-of-flight aerosol mass spectrometer, Anal. Chem., 78, 8281–8289, 2006. DeCarlo,~P F., Dunlea,~E J., Kimmel,~J R., Aiken,~A C., Sueper,~D., Crounse,~J., Wennberg,~P O., Emmons,~L., Shinozuka,~Y., Clarke,~A., Zhou,~J., Tomlinson,~J., Collins,~D R., Knapp,~D., Weinheimer,~A J., Montzka,~D D., Campos,~T., and Jimenez,~J L.: Fast airborne aerosol size and chemistry measurements above Mexico City and Central Mexico during the MILAGRO campaign, Atmos. Chem. Phys., 8, 4027–4048, 2008. Docherty,~K S., Stone,~E A., Ulbrich,~I M., DeCarlo,~P F., et al.: Apportionment of primary and secondary organic aerosols in Southern California during the 2005 Study of Organic Aerosols in Riverside (SOAR), Environ. Sci. Technol., 42, 7655–7662, 2008. Doran,~J C., Fast,~J D., Barnard,~J C., Laskin,~A., Desyaterik,~Y., and Gilles,~M K.: Applications of lagrangian dispersion modeling to the analysis of changes in the specific absorption of elemental carbon, Atmos. Chem. Phys., 8, 1377–1389, 2008. Dunlea,~E J., DeCarlo,~P F., Aiken,~A C., Kimmel,~J R., Peltier,~R E., Weber,~R J., Tomlinson,~J., Collins,~D R., Shinozuka,~Y., McNaughton,~C S., Howell,~S G., Clarke,~A D., Emmons,~L K., Apel,~E C., Pfister,~G G., van Donkelaar,~A., Martin,~R V., Millet,~D B., Heald,~C L., and Jimenez,~J L.: Evolution of Asian aerosols during transpacific transport in INTEX-B, Atmos. Chem. Phys., 9, 7257–7287, 2009. Dzepina,~K., Volkamer,~R M., Madronich,~S., Tulet,~P., Ulbrich,~I M., Zhang,~Q., Cappa,~C D., Ziemann,~P J., and Jimenez,~J L.: Evaluation of recently-proposed secondary organic aerosol models for a~case study in Mexico City, Atmos. Chem. Phys., 9, 5681–5709, 2009. Emmons,~L K., Apel,~E C., Lamarque,~J.-F., Hess,~P G., et al.: Impact of Mexico City emissions on regional air quality from MOZART-4 simulations, Atmos. Chem. Phys. Discuss., in press, 2010. Fast,~J., Aiken,~A C., Allan,~J., Alexander,~L., Campos,~T., Canagaratna,~M R., Chapman,~E., DeCarlo,~P F., de Foy,~B., Gaffney,~J., de Gouw,~J., Doran,~J C., Emmons,~L., Hodzic,~A., Herndon,~S C., Huey,~G., Jayne,~J T., Jimenez,~J L., Kleinman,~L., Kuster,~W., Marley,~N., Russell,~L., Ochoa,~C., Onasch,~T B., Pekour,~M., Song,~C., Ulbrich,~I M., Warneke,~C., Welsh-Bon,~D., Wiedinmyer,~C., Worsnop,~D R., Yu,~X.-Y., and Zaveri,~R.: Evaluating simulated primary anthropogenic and biomass burning organic aerosols during MILAGRO: implications for assessing treatments of secondary organic aerosols, Atmos. Chem. Phys., 9, 6191–6215, 2009. Fast,~J D., de Foy,~B., Acevedo Rosas,~F., Caetano,~E., Carmichael,~G., Emmons, L.,~McKenna, D.,~Mena, M.,~Skamarock, W.,~Tie, X.,~Coulter, R L., Barnard,~J C., Wiedinmyer,~C., and Madronich,~S.: A meteorological overview of the MILAGRO field campaigns, Atmos. Chem. Phys., 7, 2233–2257, 2007. George,~I J., Slowik,~J., and Abbatt,~J P D.: Chemical aging of ambient organic aerosol from heterogeneous reaction with hydroxyl radicals, Geophys. Res. Lett., 35, \doi10.1029/2008GL033884, 2008. Grieshop,~A P., Donahue,~N M., and Robinson,~A L.: Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 2: analysis of aerosol mass spectrometer data, Atmos. Chem. Phys., 9, 2227–2240, 2009a. Grieshop,~A P., Logue,~J M., Donahue,~N M., and Robinson,~A L.: Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 1: measurement and simulation of organic aerosol evolution, Atmos. Chem. Phys., 9, 1263–1277, 2009b. Grutter,~M., Basaldud,~R., Rivera,~C., Harig,~R., Junkerman,~W., Caetano,~E., and Delgado-Granados,~H.: \chem SO_2 emissions from Popocatépetl volcano: emission rates and plume imaging using optical remote sensing techniques, Atmos. Chem. Phys., 8, 6655–6663, 2008. Hallquist,~M., Wenger,~J C., Baltensperger,~U., Rudich,~Y., Simpson,~D., Claeys,~M., Dommen,~J., Donahue,~N M., George,~C., Goldstein,~A H., Hamilton,~J F., Herrmann,~H., Hoffmann,~T., Iinuma,~Y., Jang,~M., Jenkin,~M E., Jimenez,~J L., Kiendler-Scharr,~A., Maenhaut,~W., McFiggans,~G., Mentel,~Th F., Monod,~A., Prévôt,~A S H., Seinfeld,~J H., Surratt,~J D., Szmigielski,~R., and Wildt,~J.: The formation, properties and impact of secondary organic aerosol: current and emerging issues, Atmos. Chem. Phys., 9, 5155–5235, 2009. Heald,~C L., Goldstein,~A H., Allan,~J D., Aiken,~A C., Apel,~E., Atlas,~E L., Baker,~A K., Bates,~T S., Beyersdorf,~A J., Blake,~D R., Campos, T., Coe,~H., Crounse,~J D., DeCarlo,~P F., de Gouw,~J A., Dunlea,~E J., Flocke,~F M., Fried,~A., Goldan,~P., Griffin,~R J., Herndon,~S C., Holloway,~J S., Holzinger,~R., Jimenez,~J L., Junkermann,~W., Kuster,~W C., Lewis,~A C., Meinardi,~S., Millet,~D B., Onasch,~T., Polidori,~A., Quinn,~P K., Riemer,~D D., Roberts,~J M., Salcedo,~D., Sive,~B., Swanson,~A L., Talbot, R., Warneke,~C., Weber,~R J., Weibring,~P., Wennberg,~P O., Worsnop,~D R., Wittig,~A E., Zhang,~R., Zheng,~J., and Zheng,~W.: Total observed organic carbon (TOOC) in the atmosphere: a synthesis of North American observations, Atmos. Chem. Phys., 8, 2007–2025, 2008. Hodzic,~A., Jimenez,~J L., Madronich,~S., Aiken,~A C., Bessagnet,~B., Curci,~G., Fast,~J., Lamarque,~J.-F., Onasch,~T B., Roux,~G., Schauer,~J J., Stone,~E A., and Ulbrich,~I M.: Modeling organic aerosols during MILAGRO: importance of biogenic secondary organic aerosols, Atmos. Chem. Phys., 9, 6949–6981, 2009. Hodzic, A., Jimenez, J. L., Madronich, S., Canagaratna, M. R., DeCarlo, P. F., Kleinman, L., and Fast, J.: Potential contribution of semi-volatile and intermediate volatility primary organic compounds to secondary organic aerosol in the Mexico City region, Atmos. Chem. Phys. Discuss., 10, 657–710, 2010. Huffman,~J A., Docherty,~K S., Aiken,~A C., Cubison,~M J., Ulbrich,~I M., DeCarlo,~P F., Sueper,~D., Jayne,~J T., Worsnop,~D R., Ziemann,~P J., and Jimenez,~J L.: Chemically-resolved aerosol volatility measurements from two megacity field studies, Atmos. Chem. Phys., 9, 7161–7182, 2009a. Huffman,~J A., Docherty,~K S., Mohr,~C., Cubison,~M J., et al.: Chemically-resolved volatility measurements of organic aerosol from different sources, Environ. Sci. Technol., 43, 5351–5357, \doi10.1021/es803539d, 2009b. Jimenez,~J L., Jayne,~J T., Shi,~Q., Kolb,~C E., et al.: Ambient aerosol sampling using the aerodyne aerosol mass spectrometer, J. Geophys. Res.-Atmos., 108, 8425, \doi8410.1029/2001JD001213, 2003. Jimenez,~J L., Canagaratna,~M R., Donahue,~N M., Prevot,~A S H., et al.: Evolution of organic aerosols in the atmosphere, Science, 326, 1525–1529, \doi1510.1126/science.1180353, 2009. Kiendler-Scharr,~A., Zhang,~Q., Hohaus,~T., Kleist,~E., et al.: Aerosol mass spectrometric features of biogenic SOA: observations from a~plant chamber and in rural atmospheric environments, Environ. Sci. Technol., 43, 8166–8172, \doi10.1021/es901420b, 2009. Kleinman,~L I., Daum,~P H., Lee,~Y N., Senum,~G I., et al.: Aircraft observations of aerosol composition and ageing in New England and Mid-Atlantic States during the summer 2002 New England Air Quality Study field campaign, J. Geophys. Res.-Atmos., 112, D09310, \doi09310.01029/02006JD007786, 2007. Kleinman,~L I., Springston,~S R., Daum,~P H., Lee,~Y.-N., Nunnermacker,~L J., Senum,~G I., Wang,~J., Weinstein-Lloyd,~J., Alexander,~M L., Hubbe,~J., Ortega,~J., Canagaratna,~M R., and Jayne,~J.: The time evolution of aerosol composition over the Mexico City plateau, Atmos. Chem. Phys., 8, 1559–1575, 2008. Kroll,~J H., Smith,~J D., Che,~D L., Kessler,~S H., et al.: Measurement of fragmentation and functionalization pathways in the heterogeneous oxidation of oxidized organic aerosol, Phys. Chem. Chem. Phys., 11, 8005–8014, \doi8010.1039/b905289e, 2009. Lanz,~V A., Alfarra,~M R., Baltensperger,~U., Buchmann,~B., Hueglin,~C., and Prévôt,~A S H.: Source apportionment of submicron organic aerosols at an urban site by factor analytical modelling of aerosol mass spectra, Atmos. Chem. Phys., 7, 1503–1522, 2007. Lanz,~V A., Alfarra,~M R., Baltensperger,~U., Buchmann,~B., et al.: Source attribution of submicron organic aerosols during wintertime inversions by advanced factor analysis of aerosol mass spectra, Environ. Sci. Technol., 42, 214–220, \doi10.1021/es0707207, 2008. Lanz,~V A., Prévôt,~A S H., Alfarra,~M R., Mohr,~C., DeCarlo,~P F., Weimer,~S., Gianini,~M F D., Hueglin,~C., Schneider,~J., Favez,~O., D'Anna,~B., George,~C., and Baltensperger,~U.: Characterization of aerosol chemical composition by aerosol mass spectrometry in Central Europe: an overview, Atmos. Chem. Phys. Discuss., 9, 24985–25021, 2009. Lee,~T., Sullivan,~A P., Mack,~L., Jimenez,~J L., et al.: Aerosol mass spectrometer measurements of the evolution of chemical smoke markers during laboratory open burning of wildland fuels, Geophys. Res. Lett., submitted, 2010. Liousse,~C., Devaux,~C., Dulac,~F., and Cachier,~H.: Aging of Savanna biomass burning aerosols – consequences on thier optical properties, J. Atmos. Chem., 22, 1–17, 1995. Marley,~N A., Gaffney,~J S., Tackett,~M., Sturchio,~N C., Heraty,~L., Martinez,~N., Hardy,~K D., Marchany-Rivera,~A., Guilderson,~T., MacMillan,~A., and Steelman,~K.: The impact of biogenic carbon sources on aerosol absorption in Mexico City, Atmos. Chem. Phys., 9, 1537–1549, 2009. Mohr,~C., Huffman,~J A., Cubison,~M J., Aiken,~A C., et al.: Characterization of primary organic aerosol emissions from meat cooking, trash burning, and motor vehicles with high-resolution aerosol mass spectrometry and comparison with ambient and chamber observations, Environ. Sci. Technol., 43, 2443–2449, \doi10.1021/Es8011518, 2009. Molina,~L T., Kolb,~C E., de Foy,~B., Lamb,~B K., Brune,~W H., Jimenez,~J L., Ramos-Villegas,~R., Sarmiento,~J., Paramo-Figueroa,~V H., Cardenas,~B., Gutierrez-Avedoy,~V., and Molina,~M J.: Air quality in North America's most populous city – overview of the MCMA-2003 campaign, Atmos. Chem. Phys., 7, 2447–2473, 2007. Molina,~L T., Madronich,~S., Gaffney,~J S., et al.: An overview of the MILAGRO campaign: Mexico City emissions and their evolution, Atmos. Chem. Phys. Discuss., in preparation, 2010. Nemitz,~E., Jimenez,~J L., Huffman,~J A., Canagaratna,~M R., et al.: An eddy-covariance system for the measurement of surface/atmosphere exchange fluxes of submicron aerosol chemical species – first application above an urban area, Aerosol. Sci. Tech., 42, 636–657, 2008. Ng,~N L., Canagaratna,~M R., Zhang,~Q., Jimenez,~J L., Tian,~J., Ulbrich,~I M., Kroll,~J H., Docherty,~K S., Chhabra,~P S., Bahreini,~R., Murphy,~S M., Seinfeld,~J H., Hildebrandt,~L., DeCarlo,~P F., Lanz,~V A., Prevot,~A S H., Dinar,~E., Rudich,~Y., and Worsnop,~D R.: Organic aerosol components observed in worldwide datasets from aerosol mass spectrometry, Atmos. Chem. Phys. Discuss., 9, 27745–27789, 2009. Paatero,~P.: User's guide for positive matrix factorization programs PMF2.EXE and PMF3.EXE, University of Helsinki, Finland, 2007. Peltier,~R E., Sullivan,~A P., Weber,~R J., Brock,~C A., Wollny,~A G., Holloway,~J S., de Gouw,~J A., and Warneke,~C.: Fine aerosol bulk composition measured on WP-3D research aircraft in vicinity of the Northeastern United States – results from NEAQS, Atmos. Chem. Phys., 7, 3231–3247, 2007. Querol,~X., Pey,~J., Minguillón,~M C., Pérez,~N., Alastuey,~A., Viana,~M., Moreno,~T., Bernabé,~R M., Blanco,~S., Cárdenas,~B., Vega,~E., Sosa,~G., Escalona,~S., Ruiz,~H., and Artíñano,~B.: PM speciation and sources in Mexico during the MILAGRO-2006 Campaign, Atmos. Chem. Phys., 8, 111–128, 2008. Reid,~J S., Koppmann,~R., Eck,~T F., and Eleuterio,~D P.: A~review of biomass burning emissions part~II: intensive physical properties of biomass burning particles, Atmos. Chem. Phys., 5, 799–825, 2005. Robinson,~A L., Donahue,~N M., Shrivastava,~M K., Weitkamp,~E A., et al.: Rethinking organic aerosols: semivolatile emissions and photochemical aging, Science, 315, 1259–1262, 2007. Salcedo,~D., Onasch,~T B., Dzepina,~K., Canagaratna,~M R., Zhang,~Q., Huffman,~J A., DeCarlo,~P F., Jayne,~J T., Mortimer,~P., Worsnop,~D R., Kolb,~C E., Johnson,~K S., Zuberi,~B., Marr,~L C., Volkamer,~R., Molina,~L T., Molina,~M J., Cardenas,~B., Bernabé,~R M., Márquez,~C., Gaffney,~J S., Marley,~N A., Laskin,~A., Shutthanandan,~V., Xie,~Y., Brune,~W., Lesher,~R., Shirley,~T., and Jimenez,~J L.: Characterization of ambient aerosols in Mexico City during the MCMA-2003 campaign with Aerosol Mass Spectrometry: results from the CENICA Supersite, Atmos. Chem. Phys., 6, 925–946, 2006. Schauer,~J J., Rogge,~W F., Hildemann,~L M., Mazurek,~M A., et al.: Source apportionment of airborne particulate matter using organic compounds as tracers, Atmos. Environ., 30, 3837–3855, 1996. Schneider,~J., Weimer,~S., Drewnick,~F., Borrmann,~S., et al.: Mass spectrometric analysis and aerodynamic properties of various types of combustion-related aerosol particles, Int. J. Mass Spectrom., 258, 37–49, 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. Stohl,~A., Forster,~C., Frank,~A., Seibert,~P., and Wotawa,~G.: Technical note: The Lagrangian particle dispersion model FLEXPART version 6.2, Atmos. Chem. Phys., 5, 2461–2474, 2005. Stone,~E A., Snyder,~D C., Sheesley,~R J., Sullivan,~A P., Weber,~R J., and Schauer,~J J.: Source apportionment of fine organic aerosol in Mexico City during the MILAGRO experiment 2006, Atmos. Chem. Phys., 8, 1249–1259, 2008. Takegawa,~N., Miyakawa,~T., Kondo,~Y., Blake,~D R., et al.: Evolution of submicron organic aerosol in polluted air exported from Tokyo, Geophys. Res. Lett., 33, L15814, \doi15810.11029/12006GL025815, 2006. Tsimpidi,~A P., Karydis,~V A., Zavala,~M., Lei,~W., Molina,~L., Ulbrich,~I M., Jimenez,~J L., and Pandis,~S N.: Evaluation of the volatility basis-set approach for the simulation of organic aerosol formation in the Mexico City metropolitan area, Atmos. Chem. Phys., 10, 525–546, 2010. Ulbrich,~I M., Canagaratna,~M R., Zhang,~Q., Worsnop,~D R., and Jimenez,~J L.: Interpretation of organic components from Positive Matrix Factorization of aerosol mass spectrometric data, Atmos. Chem. Phys., 9, 2891–2918, 2009. Vega,~E., Reyes,~E., Ruiz,~H., Garcia,~J., et al.: Analysis of \chemPM_2.5 and \chemPM_10 in the atmosphere of Mexico City during 2000–2002, J. Air Waste Manage., 54, 786–798, 2004. Volkamer,~R., Jimenez,~J L., San Martini,~F., Dzepina,~K., et al.: Secondary organic aerosol formation from anthropogenic air pollution: rapid and higher than expected, Geophys. Res. Lett., 33, L17811, \doi10.1029/2006GL026899, 2006. Wiedinmyer,~C., Quayle,~B., Geron,~C., Belote,~A., et al.: Estimating emissions from fires in North America for air quality modeling, Atmos. Environ., 40, 3419–3432, 2006. Wood,~E C., Canagaratna,~M R., Herndon,~S C., Kroll, J. H., et al.: Investigation of the correlation between odd oxygen and secondary organic aerosol in Mexico City and Houston, in press, 2010. Yokelson,~R J., Urbanski,~S P., Atlas,~E L., Toohey,~D W., Alvarado,~E C., Crounse,~J D., Wennberg,~P O., Fisher,~M E., Wold,~C E., Campos,~T L., Adachi,~K., Buseck,~P R., and Hao,~W M.: Emissions from forest fires near Mexico City, Atmos. Chem. Phys., 7, 5569–5584, 2007. Yokelson,~R J., Crounse,~J D., DeCarlo,~P F., Karl,~T., Urbanski,~S., Atlas,~E., Campos,~T., Shinozuka,~Y., Kapustin,~V., Clarke,~A D., Weinheimer,~A., Knapp,~D J., Montzka,~D D., Holloway,~J., Weibring,~P., Flocke,~F., Zheng,~W., Toohey,~D., Wennberg,~P O., Wiedinmyer,~C., Mauldin,~L., Fried,~A., Richter,~D., Walega,~J., Jimenez,~J L., Adachi,~K., Buseck,~P R., Hall,~S R., and Shetter,~R.: Emissions from biomass burning in the Yucatan, Atmos. Chem. Phys., 9, 5785–5812, 2009. Zavala,~M., Herndon,~S C., Wood,~E C., Onasch,~T B., Knighton,~W B., Marr,~L C., Kolb,~C E., and Molina,~L T.: Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data, Atmos. Chem. Phys., 9, 6305–6317, 2009. Zhang,~K M. and Wexler,~A S.: Evolution of particle number distribution near roadways – Part I: Analysis of aerosol dynamics and its implications for engine emission measurement, Atmos. Environ., 38, 6643–6653, 2004. Zhang,~K M., Wexler,~A S., Zhu,~Y F., Hinds,~W C., et al.: Evolution of particle number distribution near roadways. Part II: The \qutroad-to-ambient process, Atmos. Environ., 38, 6655–6665, 2004. Zhang,~Q., Alfarra,~M R., Worsnop,~D R., Allan,~J D., et al.: Deconvolution and quantification of primary and oxygenated organic aerosols based on aerosol mass spectrometry. Part~1: Development and validation of the method., Environ. Sci. Technol., 39, 4938–4952, \doi4910.1021/es0485681, 2005a. 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, 2005b. Zhang,~Q., Jimenez,~J L., Canagaratna,~M R., Allan,~J D., et al.: Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically-influenced Northern Hemisphere midlatitudes, Geophys. Res. Lett., 34, L13801, \doi13810.11029/12007GL029979, 2007.