for α pinene based on a detailed mechanism Karl Ceulemans Steven Compernolle JeanFrançois Müller Belgian Institute for Space Aeronomy Brussels Belgium Eurochamp ID: 932653
Download Presentation The PPT/PDF document "Parameterization of SOA formation" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Parameterization of SOA formation for α-pinene, based on a detailed mechanism
Karl Ceulemans– Steven Compernolle – Jean-François Müller Belgian Institute for Space Aeronomy, Brussels, Belgium
Eurochamp 2 Workshop, Manchester, 2011
Slide2OutlineBOREAM: Detailed model for α-pinene SOASimulations of smog chamber experiments
10-product model parameterization including ageing
Slide3BOREAM : explicit model for α-pinene SOA
Gas phase reaction model with additional generic chemistry and aerosol formation module10000 reactions, 2500 compoundsUsing KPP solver
Capouet et al. (2008), Ceulemans et al. (2010)
Slide4Explicit chemistry
Based on advanced theoretical calculations and SARsOxidation by OH, O3 and NO3 Oxidation
products react with OH or photolyse (now also
in aerosol phase
)
Vapour
pressure
method
:
Capouet
& Müller (2006)
Slide5Generic chemistrySecond generation oxidation products lumped into semi-generic and generic products
Semi-generic: carbon number
and functional groups Generic
: carbon
number
,
vapour
pressure
classes (11) and
1explicit
functional
group
LA10HPP
10
carbons
1
alcohol
&
2
hydroperoxide
Implicit
parent structure,
with
p
vap,im
LX9cONO2
Slide6Smog chamber Photo-oxidation
low-NOx experiments (Ng et al. 2007) α-pinene and O3 given in Valorso et al. (2011)Initial: 330 ppt NO, 330 ppt NO2 , 4 ppb O3 , blacklights
α-
pinene decay well-reproducedozone : reasonable agreement, sensitive to assumptions!
Slide7Smog chamber Photo-oxidation: SOA
evolutionfor Ng et al. 2007 exp. 1 (low NOx):SOA mass yields are overestimated: experimental SOA yield is 40%, BOREAM simulation: 60%
Slide8Smog chamber Photo-oxidation: SOA
compositionMolar composition for Ng et al. (2007) exp. 1 (low NOx):
SOA is dominated by hydroxy dihydroperoxidesParticle phase chemistry of hydroperoxides?
Slide9Model performance: Photo-oxidation
two low-NOx experiments, (Ng et al. 2007) ; somewhat overestimatedmost SOA yields within factor 2
*
Slide1010-product parameter model5 scenarios:
OH (low and high-NOx )O3 (low and high-NOx ) NO3 (high-NOx)
Products fit to full model simulations with ageingDiurnal cycle for VOC, OH, HO2 and O3 ; deposition
SOA equilibrium after 12 days
Slide11Two-product model parameterizationsOdum (1996) Y : SOA mass yield
M0 : absorbing organic mass αi : mass stoichiometric coefficient of product i Ki
: Pankow (1994) absorption equilibrium constant
Slide12Temperature dependence of parameters
Absorption equilibrium constant:Stoichiometric coefficient
0°C
30°C
Slide1310-product model parameters
scenario
product
m
3
µ
g
-1
kJ mol
-1
α
-
pinene
+ OH, low
NOx
1
0.307
-0.022
6.98
85.6
2
0.211
-0.0135
0.117
22.2
α
-
pinene
+ OH, high
NOx
3
0.028
-0.040
0.762
132.2
4
0.109
-0.025
0.00486
85.3
α
-
pinene
+ O
3
, low
NOx
5
0.282
-0.0132
4.155
86.8
6
0.142
-0.025
0.0158
77.1
α
-
pinene
+ O
3
, high
NOx
7
0.016
-0.057
0.837
161.8
8
0.213
-0.0054
0.00326
111.4
α
-
pinene
+ NO
3
high
NOx
9
0.018
-0.049
0.493
172.4
10
0.251-0.0150.00092147.6
Reactions
Slide1410-product model curves at 298K
More SOA in low-NOx than in high-NOx (factor 8 difference)
α-pinene + OH leads to more SOA than α-pinene + O3
Slide15Why more SOA in low than
high-NOx ?
High-
NO
x
Low
-
NO
x
Hydroperoxides (condensable)
Peroxy acyl nitrates
nitrates
More
decompositions
More volatile
products
Slide16Verification at intermediate NO
x
Full model
parameter model
(modified)
Slide17Sensitivity to photolysis and oxidants
Not accounting for photolysis of SOA during ageing Accumulation of condensables very high yieldsNot very sensitive to chosen OH or HO2
Slide18Comparison with other parameterizations
Low-NOx : Yields in this study are higher than for others, Aging impactVery low-NO
x But, also high yields in Ng et al. (2007)
High-NOx :
similar to Presto et al. (2005)
T = 298 K
Slide19SummaryBOREAM simulations of smog chamber photo-oxidation: most SOA yields within factor 2Some overestimations for low-NOx
10-product model fit to explicit box model BOREAM including agingLow-NOx SOA higher than previous parameterizations based on smog chambers (impact aging)Photolysis of compounds in aerosol phase importantEVAPORATION:
New vapour pressure estimation method
Slide20Thank you for your attention!
Slide21α
-pinene + O
3
and pinonaldehyde chemistry