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Detailed chemical modelling based on the Master Chemical Mechanism (MCM)

Detailed chemical modelling based on the Master Chemical Mechanism (MCM). Mike Jenkin EMMA Group Department of Environmental Science and Technology m.jenkin@ ic . ac .uk. Master Chemical Mechanism. Developed by a consortium of groups Imperial College London Leeds Meteorological Office

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Detailed chemical modelling based on the Master Chemical Mechanism (MCM)

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  1. Detailed chemical modelling based on the Master Chemical Mechanism (MCM) Mike Jenkin EMMA Group Department of Environmental Science and Technology m.jenkin@ic.ac.uk

  2. Master Chemical Mechanism • Developed by a consortium of groups • Imperial College London • Leeds • Meteorological Office • NETCEN (AEA Technology)

  3. MCM: chemical processing of emissions NOX nitrate VOC CO2, H2O CH4 SO2 sulphate emissions

  4. MCM: chemical processing of emissions NOX nitrate CO2, H2O VOC Oxidant (O3, NO2, PAN) Secondary Organic Aerosol (SOA) emissions

  5. Master Chemical Mechanism (MCM v3) (http://chem.leeds.ac.uk) • Degradation of CH4 and 124 non-methane VOC • ca. 4,500 chemical species • ca. 12,500 chemical reactions • Non-methane VOC selected primarily on the basis of UK National Atmospheric Emissions Inventory (NAEI) • Provides a reasonable representation of major organic compounds emitted into the boundary layer in UK and other populated regions

  6. VOC degraded in MCM v3 (http://chem.leeds.ac.uk) • 22 alkanes (C1-C12) • 16 alkenes (C2-C6) • 2 dienes (C4-C5) • 2 monoterpenes (C10) • 1 alkyne (C2) • 18 aromatics (C6-C11) • 6 aldehydes (C1-C5) • 10 ketones (C3-C6) • 17 alcohols (C1-C6) • 10 ethers (C2-C7) • 8 esters (C2-C6) • 3 carboxylic acids (C1-C3) • 2 other oxygenates (C3) • 8 chlorocarbons (C1-C2) 125 hydrocarbons, oxygenated and chlorinated VOC representative of a variety of important source sectors e.g. road transport, solvent usage, biogenic

  7. MCM scheme writing framework Saunders et al., Atmos. Chem. Phys. 3, 161-180, 2003 Jenkin et al., Atmos. Chem. Phys. 3, 181-193, 2003

  8. emission VOC OH, O3, NO3 first generation products OH, O3, NO3, hu second generation products CO2

  9. Applications of the MCM Calculation of organic species distribution for comparison with and supplementation of field measurements

  10. Emitted VOC Products alkanes Majority of emitted VOC will be oxidised to: aldehydes (C1- C?) ketones (C3- C?) nitrates (C1- C?) PAN(s) (C2- C?) hydroperoxides alcohols esters carboxylic acids percarboxylic acids bi- and multi-functional products (esp. hydroxy-carbonyls and nitrates and dicarbonyls) alkenes/dienes alkynes aromatics carbonyls ethers esters acids chlorocarbons

  11. Trajectories to Silwood Park, 28 July – 3 August 1999 N 31/7 28/7 30/7 29/7 1/8 2/8 3/8

  12. Ozone at Silwood Park, 28 July – 3 August 1999(EU PRIME campaign)

  13. Applications of the MCM Assessment of comparative importance of: Free radical sources: O3 + hu Speciated alkenes + O3 Speciated carbonyls + hu HONO + hu Free radical sinks: OH + NO2 HNO3 HO2 + HO2  H2O2 + O2 RO2 + NO  RONO2 RO2 + HO2 ROOH + O2 Assessment of oxidant formation associated with different VOCs/VOC source sectors

  14. Reduced mechanism Common Representative Intermediates Mechanism (CRI v1) CRI v1 121 VOC 250 species 570 reactions Jenkin et al., Atmospheric Environment, 36, 4725-4734, 2002

  15. Reduced mechanism Common Representative Intermediates Mechanism (CRI v1) CRI v1 121 VOC 250 species 570 reactions Jenkin et al., Atmospheric Environment, 36, 4725-4734, 2002 VOC CO2, H2O

  16. Reduced mechanism Common Representative Intermediates Mechanism (CRI v1) CRI v1 121 VOC 250 species 570 reactions Jenkin et al., Atmospheric Environment, 36, 4725-4734, 2002 O3 O3 O3 O3 VOC CO2, H2O

  17. CRI vs MCM

  18. Urban Urban dM dlogDa (gm-3) Urban Rural Urban Semi Rural Aerodynamic Diameter (nm) Importance of organics in aerosols (slide from Hugh Coe, UMIST)

  19. emission VOC OH, O3, NO3 first generation products OH, O3, NO3, hu second generation products CO2

  20. gas phase condensed phase emission VOC OH, O3, NO3 first generation products first generation products OH, O3, NO3, hu second generation products second generation products CO2

  21. gas phase condensed phase emission monoterpenes OH, O3, NO3 first generation products OH, O3, NO3, hu second generation products C5-C7 multi-oxygenated species (probably WSOC) CO2

  22. gas phase condensed phase emission aromatics OH, O3, NO3 first generation products OH, O3, NO3, hu second generation products (probably WSOC) CO2

  23. Equilibrium partitioning gas phase organic aerosol, OA kin X (a) X (g) kout [X](a)/[X](g) = kin[OA]/kout = Kp [OA]

  24. European Photoreactor (EUPHORE) Valencia, Spain

  25. Photo-oxidation of a-pinene/NOX EU OSOA campaign at EUPHORE

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