Detailed chemical modelling based on the Master Chemical Mechanism (MCM) Mike Jenkin EMMA Group Department of Environmental Science and Technology

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

MCM: chemical processing of emissions NO X nitrate emissions VOC CH 4 SO 2 CO 2, H 2 O sulphate

MCM: chemical processing of emissions NO X nitrate emissions Oxidant (O 3, NO 2, PAN) VOC CO 2, H 2 O Secondary Organic Aerosol (SOA)

Degradation of CH 4 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 Master Chemical Mechanism (MCM v3) (

22 alkanes (C 1 -C 12 ) 16 alkenes (C 2 -C 6 ) 2 dienes (C 4 -C 5 ) 2 monoterpenes (C 10 ) 1 alkyne (C 2 ) 18 aromatics (C 6 -C 11 ) 6 aldehydes (C 1 -C 5 ) 10 ketones (C 3 -C 6 ) 17 alcohols (C 1 -C 6 ) 10 ethers (C 2 -C 7 ) 8 esters (C 2 -C 6 ) 3 carboxylic acids (C 1 -C 3 ) 2 other oxygenates (C 3 ) 8 chlorocarbons (C 1 -C 2 ) 125 hydrocarbons, oxygenated and chlorinated VOC representative of a variety of important source sectors e.g. road transport, solvent usage, biogenic VOC degraded in MCM v3 (

Saunders et al., Atmos. Chem. Phys. 3, , 2003 Jenkin et al., Atmos. Chem. Phys. 3, , 2003 MCM scheme writing framework

VOC second generation products first generation products CO 2 OH, O 3, NO 3 OH, O 3, NO 3, h emission

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

alkanes alkenes/dienes aromatics carbonyls ethers esters acids alkynes chlorocarbons Emitted VOCProducts Majority of emitted VOC will be oxidised to: aldehydes (C 1 - C?) ketones (C 3 - C?) nitrates (C 1 - C?) PAN(s) (C 2 - C?) hydroperoxides alcohols esters carboxylic acids percarboxylic acids bi- and multi-functional products (esp. hydroxy- carbonyls and nitrates and dicarbonyls)

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

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

Applications of the MCM Assessment of comparative importance of: Free radical sources: O 3 + h Speciated alkenes + O 3 Speciated carbonyls + h HONO + h Free radical sinks: OH + NO 2 HNO 3 HO 2 + HO 2 H 2 O 2 + O 2 RO 2 + NO RONO 2 RO 2 + HO 2 ROOH + O 2 Assessment of oxidant formation associated with different VOCs/VOC source sectors

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

Reduced mechanism Common Representative Intermediates Mechanism (CRI v1) CRI v1 121 VOC 250 species 570 reactions VOCCO 2, H 2 O Jenkin et al., Atmospheric Environment, 36, , 2002

Reduced mechanism Common Representative Intermediates Mechanism (CRI v1) CRI v1 121 VOC 250 species 570 reactions VOCCO 2, H 2 O Jenkin et al., Atmospheric Environment, 36, , 2002 O3O3 O3O3 O3O3 O3O3

CRI vs MCM

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

VOC second generation products first generation products CO 2 OH, O 3, NO 3 OH, O 3, NO 3, h emission

VOC second generation products first generation products CO 2 first generation products second generation products OH, O 3, NO 3 OH, O 3, NO 3, h emission condensed phase gas phase

monoterpenes second generation products first generation products CO 2 C 5 -C 7 multi- oxygenated species (probably WSOC) OH, O 3, NO 3 OH, O 3, NO 3, h emission condensed phase gas phase

aromatics second generation products first generation products CO 2 OH, O 3, NO 3 OH, O 3, NO 3, h emission condensed phase gas phase (probably WSOC)

X (g) gas phase X (a) Equilibrium partitioning k in k out [X] (a) /[X] (g) = k in [OA]/k out = K p [OA] organic aerosol, OA

European Photoreactor (EUPHORE) Valencia, Spain

Photo-oxidation of -pinene/NO X EU OSOA campaign at EUPHORE