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Modelling SOA in EMEP: Experiments with the VBS Approach

This paper discusses the evaluation of earlier EMEP-SOA models using smog chamber data and presents preliminary results of the EMEP VBS-model. It highlights the need for a new EMEP-SOA model based on recent advancements in the field. The paper also compares the revised SOAschemes to modern parameterized a-pinene SOA models.

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Modelling SOA in EMEP: Experiments with the VBS Approach

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  1. Modelling SOA in EMEP: Experiments with the VBS ApproachRobert Bergström(1,2) and David Simpson(3,4)Robert.Bergstrom@smhi.se, David.Simpson@met.no (1) Department of Chemistry, University of Gothenburg, Sweden(2) Swedish Meteorological and Hydrological Institute, SE-601 76 Norrköping, Sweden (3) The Norwegian Meteorological Institute, Oslo, Norway (4) Dept of Radio and Space Science, Chalmers University of Technology, Gothenburg, Sweden

  2. Outline • Earlier EMEP SOA models • Evaluation (using smog chamber data) • EMEP VBS-model • Preliminary results

  3. History of EMEP-SOA – Kamens et al., 1999

  4. Kamens et al., 1999 aerosol from a-pinene +O3 • Kamens et al., 1999

  5. First EMEP-SOA – Andersson-Sköld & Simpson 2001 Based on Kamens et al., 1999 Added NOx-chemistry, photolysis, dimer formation (from gas phase reaction of pinic and norpinic acid) Implementation in 3d-model (EMEP)

  6. First EMEP-SOA “Kam-2” – Andersson-Sköld & Simpson 2001 Added ca 17 species and 30 reactions to the standard EMEP photochemistry scheme

  7. Simpson et al., JGR 2007 (Kam2-X)

  8. Kamens & Jaoui, 2001

  9. Li et al., 2007 “Kamens 2007” • Updating the Kamens 2001 scheme, exploratory “oligomerization” reactions introduced

  10. A new EMEP-SOA model needed(?) • Testing: • Kamens 2001 • Kamens 2007 • Volatility Basis Set - based methods (Donahue et al., Lane et al.)

  11. aK model by Svendby et al., 2008 Example of Evaluation (dark ozonolysis, SOA yield) • Kamens2007 VBS model by Pathak et al., 2007

  12. Results – dark ozonolysis studies Summary The EMEP MSC-W model for secondary organic aerosol (SOA) has so far made use of a semi-explicit gas/particle partitioning scheme for a-pinene, in which a-pinene chemistry is represented by 30 reactions between 17 species. The mechanism, described in Andersson-Sköld and Simpson (2001), was based upon a dark-chemistry scheme for a-pinene presented by Kamens et al. (1999). The original EMEP SOA model was tested against 11 smog-chamber experiments in 2001, and found to reproduce observed SOA quite well across a wide-range of temperature and a-pinene levels. In recent years a number of new studies have become available which necessitate revisions and new testing of the EMEP SOA scheme. As shown in Simpson et al. (2007), assumptions concerning the vapour pressure of specific compounds can have pronounced effects on predicted SOA amounts. The Kamens group has also presented new ideas for the a-pinene mechanism (e.g., Li et al., 2007). The EMEP SOA scheme is being re-written in the light of these new developments, and here we present some preliminary results for revised SOA schemes compared to recent smog-chamber data and to some modern parameterised a-pinene SOA models (Two-product, a-K, model by Svendby et al., 2008 and Volatility Basis Set models by Pathak et al., 2007) Sensitivity to NOx/VOC ratio Sensitivity to Temperature Low-NOx studies EMEP / Kamens type schemes K07 – Li et al., 2007 scheme AS01e – Andersson-Sköld & Simpson, 2001 Evaluation of gas/particle SOA mechanisms for a-pinene for the EMEP modelRobert Bergström (1,2) and David Simpson (3,4)(1) Department of Chemistry, University of Gothenburg, Sweden, (2) Swedish Meteorological and Hydrological Institute, SE-601 76 Norrköping, Sweden Robert.Bergstrom@smhi.se(3) The Norwegian Meteorological Institute, Oslo, Norway, (4) Dept of Radio and Space Science, Chalmers University of Technology, Gothenburg, Sweden David.Simpson@met.no aK & VBS models S07a –box-v of Kam2 fr Simpson et al., 2007 S07x –box-v of Kam2X fr Simpson et al., 2007 References– models Andersson-Sköld, Y. & Simpson, D. (2001), Secondary organic aerosol formation in Northern Europe: A model study, J. Geophys. Res., 106, 7357-7374. Kamens, R.; Jang, M.; Chien, C. & Leach, K. (1999), Aerosol Formation from the Reaction of a-Pinene and Ozone Using a Gas-Phase Kinetics-Aerosol Partitioning Model, Environ. Sci. Technol., 33, 1430-1438. Kamens, R.M. & Jaoui, M. (2001), Modeling Aerosol Formation from a-Pinene + NOx in the Presence of Natural Sunlight Using Gas-Phase Kinetics and Gas-Particle Partitioning Theory, Environ. Sci. Technol., 35, 1394-1405. Li, Q.; Hu, D.; Leungsakul, S. & Kamens, R.M. (2007), Large outdoor chamber experiments and computer simulations: (I) Secondary organic aerosol formation from the oxidation of a mixture of d-limonene and a-pinene, Atmos. Environ., 41, 9341-9352. Pathak, R.K.; Presto, A.A.; Lane, T.E.; Stanier, C.O.; Donahue, N.M. & Pandis, S.N. (2007), Ozonolysis of a-pinene: parameterization of secondary organic aerosol mass fraction, Atmos. Chem. Phys., 7, 3811-3821. Simpson, D.; Yttri, K. E.; Klimont, Z.; Kupiainen, K.; Caseiro, A.; Gelencsér, A.; Pio, C. & Legrand, M. (2007), Modeling carbonaceous aerosol over Europe: Analysis of the CARBOSOL and EMEP EC/OC campaigns, J. Geophys. Res., 112, D23S14. Svendby, T.M.; Lazaridis, M. & Tørseth, K. (2008), Temperature dependent secondary organic aerosol formation from terpenes and aromatics, J. Atmos. Chem., 59, 25-46. measurements Cocker III, D.R.; Clegg, S.L.; Flagan, R.C. & Seinfeld, J.H. (2001), The effect of water on gas-particle partitioning of secondary organic aerosol. Part I: a-pinene/ozone system , Atmos. Environ., 35, 6049-6072. Griffin, R.J.; Cocker III, D.R.; Flagan, R.C. & Seinfeld, J.H. (1999), Organic aerosol formation from the oxidation of biogenic hydrocarbons, J. Geophys. Res., 104, 3555-3567. Hallquist, M.; Wängberg, I.; Ljungström, E.; Barnes, I. & Becker, K.-H. (1999), Aerosol and Product Yields from NO3 Radical-Initiated Oxidation of Selected Monoterpenes, Environ. Sci. Technol., 33, 553-559. Hoffmann, T.; Odum, J.R.; Bowman, F.; Collins, D.; Klockow, D.; Flagan, R.C. & Seinfeld, J.H. (1997), Formation of Organic Aerosols from the Oxidation of Biogenic Hydrocarbons, J. Atmos. Chem., 26, 189-222. Jang, M. & Kamens, R.M. (1999), Newly characterized products and composition of secondary aerosols from the reaction of a-pinene with ozone, Atmos. Environ., 33, 459-474. Pathak, R.K.; Stanier, C.O. Donahue, N.M. & Pandis, S.N. (2007), Ozonolysis of a-pinene at atmospherically relevant concentrations: Temperature dependence of aerosol mass fractions (yields), J. Geophys. Res., 112, D03201. Presto, A.A.; & Donahue, N. M. (2006), Investigation of a-pinene + Ozone Secondary Organic Aerosol Formation at Low Total Aerosol Mass, Environ. Sci. Technol., 40, 3536-3543. Presto, A.A.; Huff Hartz, K.E. & Donahue, N. M. (2005), Secondary Organic Aerosol Production from Terpene Ozonolysis. 2. Effect of NOx Concentration, Environ. Sci. Technol., 39, 7046-7054. Saathoff, H.; Naumann, K.-H.; Möhler, O.; Jonsson, Å.M.; Hallquist, M.; Kiendler-Scharr, A.; Mentel, Th.F.; Tillmann, R. & Schurath, U. (2009), Temperature dependence of yields of secondary organic aerosols from the ozonolysis of a-pinene and limonene, Atmos. Chem. Phys., 9, 1551-1577. Shilling, J.E.; Chen, Q.; King, S.M.; Rosenoern, T.; Kroll, J.H.; Worsnop, D.R.; McKinney, K.A. & Martin, S.T. (2008), Particle mass yield in secondary organic aerosol formed by the dark ozonolysis of a-pinene, Atmos. Chem. Phys., 8, 2073-2088. Yu, J.; Cocker III, D.R.; Griffin, R.J.; Flagan, R.C. & Seinfeld, J.H. (1999), Gas-Phase Ozone Oxidation of Monoterpenes: Gaseous and Particulate Products, J. Atmos. Chem., 34, 207-258. Acknowledgement This work was funded by the Swedish Environmental Protection Agency, as part of the Swedish Clean Air Research Programme (SCARP) and by EU, as part of the European Integrated project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI). Svendby08 – aK model by Svendby et al., 2008 Pathak07dry – VBS model by Pathak et al., 2007 NO3 reaction • High NOx experiments are poorly modelled (by the EMEP/Kamens schemes) • Many of the Kamens-based schemes have a tendency to underestimate SOA at high temperatures and at low (measured) OA levels • The box model version of the Kam2X scheme overestimates SOA substantially for most experiments • The 2-product model of Svendby et al. (2008) and the VBS model by Pathak et al. (2007) are both giving SOA concentrations in better agreement with measurements in most cases

  13. The Volatility Basis Set (VBS) approach to (S)OA modelling

  14. VBS: Gas – Particle partitioning • Define a partitioning coefficient xi, for compound i • where • Ci* = effective saturation concentration • COA= mass concentration of OA

  15. VBS: The basis set • Use a fixed set of effective saturation concentrations, i.e., only ai values are free parameters when fitting experimental data, e.g., • {Ci*} = {0.01, 0.1, 1, 10, 100, 1000, 10 000, 100 000} mg m-3 • {Ci*} = {1, 10, 100, 1000} mg m-3

  16. [From Neil Donahue]

  17. Temperature dependence • Clausius-Clapeyron equation for saturation concentration

  18. Reactive / Aging POA emissions • Shrivastava et al. (2008) use a VBS-approach for treating primary organic aerosol (POA) emissions • Assume a lot of the POA emissions are of intermediate volatility and that chemical processing of these gas phase components lead to a lowering of the volatility and increased partitioning into the particle phase • Total POA/IVOC emissions are assumed to be 2.5 times larger than the “traditional” estimates for “inert” POA but most of the direct emissions are in the gaseous phase

  19. Aging POA emissions • Shrivastava et al., 2008

  20. EMEP – VBSVBS-chemistry based on Lane et al., 2008

  21. EMEP – VBS-SOA • Standard EMEP photochemistry model with added VBS treatment of SOA (and POA) • EUCAARI/TNO emissions for EC/OC used (Denier van der Gon et al., 2009) • Vegetation fire emissions from Global Fire Emission Database (GFEDv2), 8day time resolution (2001-2007) (van der Werf et al., 2006, Giglio et al., 2003)http://ess1.ess.uci.edu/%7Ejranders/data/GFED2/

  22. EMEP – VBS-SOA • Including VBS-SOA schemes for • Monoterpenes (BSOA) • Isoprene (BSOA) • Alkanes (ASOA) • Alkenes (ASOA) • Aromatics (ASOA)

  23. EMEP – VBS - POA • Different assumptions regarding the POA emissions are tested: • Traditional inert (nonvolatile) POA emissions • Emissions distributed into nine volatility bins and using the same assumptions as Shrivastava et al. (2008) regarding “missing” IVOC emissions in the POA inventories

  24. EMEP – VBS - aging • Different assumptions regarding the aging reactions (by OH) are tested: • No aging • Only aging of the primary emissions • Aging of both POA (k=4×10-11 cm3 molecule-1 s-1)and SOA (k=4×10-12 cm3 molecule-1 s-1) • see Lane et al., Atmos. Environ. 42 (2008) p7439-7451 for a test of SOA aging reactions using the PMCAMx VBS model

  25. EMEP – VBS preliminary results • Four different model versions have been run for the years 2002-2003, 2006, 2007 • Validation just started

  26. OC – yearly average conc 2003 (mg C / m3) Inert POA emissions VBS-POA (no aging) Age POA + SOA Age POA

  27. POA & OPOA (from FFUEL)–2007 (mg C / m3) Inert POA emissions VBS-POA (no aging) VBS POA-aging Oxidised POA VBS POA-aging Fresh POA

  28. ASOA – yearly average conc 2003 (mg C / m3) Inert POA emissions VBS-POA (no aging) Age POA + SOA Age POA

  29. BSOA – yearly average conc 2003 (mg C / m3) Inert POA emissions VBS-POA (no aging) Age POA + SOA Age POA

  30. BSOA – yearly average conc 2003 (mg C / m3) (Age POA) Isoprene- BSOA (Age-POA) Terpene- BSOA (Age POA + SOA) Terpene- BSOA (Age POA+ SOA) Isoprene- BSOA

  31. Preliminary results

  32. On-going work… • Evaluation against EUCAARI measurements (AMS, etc) – to be presented at IAC Helsinki (August 2010)

  33. Acknowledgements • Thanks to: • Swedish Clean Air Research Programme (SCARP) • EMEP project • EU EUCAARI project • Norwegian SORGA project

  34. Next generation VBS-2D?

  35. 2D-VBS: Keep track of O:C ratios as well as volatility • VBS-2d discussion

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