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

Mike Jenkin

EMMA Group

Department of Environmental Science and Technology

[email protected]


Master Chemical Mechanism Mechanism (MCM)

  • Developed by a consortium of groups

  • Imperial College London

  • Leeds

  • Meteorological Office

  • NETCEN (AEA Technology)


MCM: chemical processing of emissions Mechanism (MCM)

NOX

nitrate

VOC

CO2, H2O

CH4

SO2

sulphate

emissions


MCM: chemical processing of emissions Mechanism (MCM)

NOX

nitrate

CO2, H2O

VOC

Oxidant (O3, NO2, PAN)

Secondary Organic Aerosol (SOA)

emissions


Master Chemical Mechanism (MCM v3) Mechanism (MCM)

(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


VOC degraded in MCM v3 Mechanism (MCM)

(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


MCM scheme writing framework Mechanism (MCM)

Saunders et al., Atmos. Chem. Phys. 3, 161-180, 2003

Jenkin et al., Atmos. Chem. Phys. 3, 181-193, 2003


emission Mechanism (MCM)

VOC

OH, O3, NO3

first generation

products

OH, O3, NO3, hu

second generation

products

CO2


Applications of the MCM Mechanism (MCM)

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


Emitted VOC Mechanism (MCM)

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


Trajectories to silwood park 28 july 3 august 1999
Trajectories to Silwood Park, 28 July – 3 August 1999 Mechanism (MCM)

N

31/7

28/7

30/7

29/7

1/8

2/8

3/8


Ozone at silwood park 28 july 3 august 1999 eu prime campaign
Ozone at Silwood Park, 28 July – 3 August 1999 Mechanism (MCM)(EU PRIME campaign)


Applications of the MCM Mechanism (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


Reduced mechanism Mechanism (MCM)

Common Representative Intermediates Mechanism (CRI v1)

CRI v1

121 VOC

250 species

570 reactions

Jenkin et al., Atmospheric Environment, 36, 4725-4734, 2002


Reduced mechanism Mechanism (MCM)

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


Reduced mechanism Mechanism (MCM)

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


CRI vs MCM Mechanism (MCM)


Urban Mechanism (MCM)

Urban

dM dlogDa (gm-3)

Urban

Rural

Urban

Semi Rural

Aerodynamic Diameter (nm)

Importance of organics in aerosols (slide from Hugh Coe, UMIST)


emission Mechanism (MCM)

VOC

OH, O3, NO3

first generation

products

OH, O3, NO3, hu

second generation

products

CO2


gas phase Mechanism (MCM)

condensed

phase

emission

VOC

OH, O3, NO3

first generation

products

first generation

products

OH, O3, NO3, hu

second generation

products

second generation

products

CO2


gas phase Mechanism (MCM)

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


gas phase Mechanism (MCM)

condensed

phase

emission

aromatics

OH, O3, NO3

first generation

products

OH, O3, NO3, hu

second generation

products

(probably WSOC)

CO2


Equilibrium Mechanism (MCM)

partitioning

gas phase

organic

aerosol, OA

kin

X (a)

X (g)

kout

[X](a)/[X](g) = kin[OA]/kout

= Kp [OA]


European Photoreactor (EUPHORE) Mechanism (MCM)

Valencia, Spain


Photo-oxidation of Mechanism (MCM)a-pinene/NOX

EU OSOA campaign at EUPHORE


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