Karl Ceulemans – Jean-François Müller – Steven Compernolle – Jenny Stavrakou
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Transcript of Karl Ceulemans – Jean-François Müller – Steven Compernolle – Jenny Stavrakou
Parameterization of Global Parameterization of Global Monoterpene Monoterpene SOA formation and Water Uptake, SOA formation and Water Uptake, Based Based on a Near-explicit Mechanismon a Near-explicit MechanismKarl Ceulemans – Jean-François Müller – Steven Compernolle – Jenny StavrakouBelgian Institute for Space Aeronomy, Brussels, Belgium
ACM Conference, Davis, 2010
Secondary Organic Aerosol Secondary Organic Aerosol modelingmodeling
SOA in smog chambers
Detailed SOA box models
Parameter models
Atmospheric aerosols
Aerosol in Global models
???Explicit models too
large, many model uncertainties
Do smog chambers represent Do smog chambers represent atmospheric SOA well? atmospheric SOA well? Photochemical aging?Photochemical aging?
SOA in smog chambers
Detailed SOA box models
Parameter model +
online aging scheme
Atmospheric aerosols
Aerosol in Global models
??=
+OH
Parameters from box model simulations
OutlineOutline
BOREAM: Near-explicit model for α-pinene SOA
10-product model parameterization including aging
Water uptakeGlobal modelling
BOREAM : explicit model for BOREAM : explicit model for αα--pinene SOApinene SOA
Gas phase reaction model with additional generic chemistry and aerosol formation module
10000 reactions, 2500 compoundsUsing KPP solverCapouet et al. (2008), Ceulemans et al. (2010)
Explicit chemistryExplicit chemistry• Based on advanced theoretical calculations and SARs•Oxidation by OH, O3 and NO3
•Oxidation products react with OH or photolyse (now also in aerosol phase)
Model performance: Photo-Model performance: Photo-oxidationoxidation
two low-NOx experiments (Ng et al. 2007)most SOA yields within factor 2
10-product parameter model10-product parameter model5 scenarios:
◦ OH (low and high-NOx )◦ O3 (low and high-NOx ) ◦ NO3 (high-NOx)
Products fit to full model simulations with agingDiurnal cycle for VOC, OH, HO2 and O3 ;
depositionSOA equilibrium after 12 days
APOHHO22' APOHHO21' HO APINOHO2
NO APOHNO2' APOHNO1' NO APINOHO2APINOHO2 OH APIN
432
221
Two-product model Two-product model parameterizationsparameterizations Odum (1996)
Y : SOA mass yield M0 : absorbing organic mass αi : mass stoichiometric coefficient of product i Ki : Pankow (1994) absorption equilibrium constant
i i
ii
MKKMY
00 1
gasi
aerii CM
CK
,0
,
.
Temperature dependence of Temperature dependence of parametersparameters
Absorption equilibrium constant:
Stoichiometric coefficient )())11(exp()()()( ,,
rr
i
rripip m
mTTR
HTTTKTK
))298(exp()( 10 TT iii 0°C
30°C
10-product model parameters10-product model parameters
)())11(exp()()()( ,,rr
i
rripip m
mTTR
HTTTKTK
))298(exp()( 10 TT iii
0i 1
i )298(,ipK iHscenario product m3 µg-1 kJ mol-1
α-pinene + OH, low NOx
1 0.307 -0.022 6.98 85.62 0.211 -
0.01350.117 22.2
α-pinene + OH, high NOx
3 0.028 -0.040 0.762 132.24 0.109 -0.025 0.0048
685.3
α-pinene + O3, low NOx
5 0.282 -0.0132
4.155 86.8
6 0.142 -0.025 0.0158 77.1α-pinene + O3,
high NOx 7 0.016 -0.057 0.837 161.88 0.213 -
0.00540.0032
6111.4
α-pinene + NO3 high NOx
9 0.018 -0.049 0.493 172.410 0.251 -0.015 0.00092 147.6
i i
ii
MKKMY
00 1
APOHHO22' APOHHO21' HO APINOHO2
NO APOHNO2' APOHNO1' NO APINOHO2APINOHO2 OH APIN
432
221
APO3HO22' APO3HO21' HO APINO3O2
NO APO3NO2' APO3NO1' NO APINO3O2APINO3O2 O APIN
872
265
3
Reactions
APNO32.' APNO31' NO APIN 1093
OA
pineneii MW
MWTT ).()('
10-product model curves at 10-product model curves at 298K298K
More SOA in low-NOx than in high-NOx (factor 8 difference)
α-pinene + OH leads to more SOA than α-pinene + O3
Why more SOA in low than high-Why more SOA in low than high-NONOxx ? ?
++ O2
OH OHO O
+ NO
OHO NO210%
+ NO 90%OH
O
decomposition
OO
pinonaldehyde
+ HO2
OHO OH
++ O2
OH
O
OHO OH
O
+ HO2
O
OHO OH
OH
O2
OH++
OO
O O
NONO2+ +O
O
O ON O
O CH2
O + CO2
High-NOx
Low-NOx
Hydroperoxides (condensable)
Peroxy acyl nitrates
nitrates
More decompositionsMore volatile products
Verification at intermediate NOVerification at intermediate NOx x
Full modelparameter model(modified)
Sensitivity to photolysis and Sensitivity to photolysis and oxidantsoxidants
Not accounting for photolysis of SOA during aging Accumulation of condensables very high yields Not very sensitive to chosen OH or HO2
Comparison with other Comparison with other parameterizationsparameterizations
Low-NOx : Yields in this
study are higher than for others, ◦ Aging impact◦ Very low-NO x
But, also high yields in
Ng et al. (2007)
High-NOx : similar to Presto
et al. (2005)
T = 298 K
Water uptakeWater uptakeParameterizations were obtained for dry
conditionsWater uptake
◦ increases molecule number absorbing phase
more condensation organic compounds
◦ Non-ideality effectsActivity coefficients correct for non-
ideality
i
Fitted activity coefficientsFitted activity coefficientsagainst BOREAM , (impact water non-ideality on organic fraction)
OH2 Org
Impact of water uptake on SOAImpact of water uptake on SOA
Significant increase of SOA due to waterGood agreement between full and parameter modelConstant activity coefficients cause errors at high RH
Global ModelingGlobal ModelingUsing global CTM IMAGESv2 (Stavrakou et al. 2009)Parameter model α-pinene used for SOA from all
monoterpenesOther types of Organic Aerosol:
◦ Isoprene: Henze and Seinfeld (2006)◦ Sesquiterpenes: Griffin et al.(1999)◦ Aromatics: Henze et al. (2008)◦ Small dicarbonyls (cloud processing and aqueous aerosol): Stavrakou et al. (2009)
POA: non-volatile (Bond et al. 2004, Van der Werf et al. 2006)
ResultsResultsUGlobal SOA production(Tg/year)
Images No
water
ImagesWith water
Henze et al. (2008)
Tsigaridis
(2007)
Pye et al.
(2010)
Farinaet al.
(2010)
Monoterpenes 18.8 20.7 8.7 12.113.7
17.2Sesquiterpene
s8.2 11.0 2.1 0 3.9
Isoprene 35.6 49.5 14.4 4.6 7.9 6.5Aromatics 3.8 4.0 3.5 1.8 8.5* 1.6
Dicarbonyls 33.2 34.0 0 0 0 0Total SOA 100 119 30 19 30.1 28.9
POA source* 62 62 70 44 39.2* 81SOA
burden(Tg)1.75 2.12 0.81 0.82 0.54
Lifetime (days)
6.4 6.5 9.8 16.1 6.8
Global model results (July Global model results (July 2004)2004)
Monoterpene SOA (μg m-3) fraction of total OA (%)
Total OA (μg m-3) Total SOA (μg m-3)
Modeled impact of water uptake on Modeled impact of water uptake on surface OA concentratiossurface OA concentratios
ResultsResultsComparisons with observations: U.S.Comparisons with observations: U.S.
• too large seasonal variation of OC in Eastern US
• MEGAN emissions might be overestimated by a factor of 2 in Eastern US (Warneke et al., 2010; Stavrakou et al., 2010)
• water uptake: mostly associated with isoprene SOA, highly uncertain
Comparisons with observations Comparisons with observations (cont.)(cont.)
SummarySummary10-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 important
Global modeling with IMAGESv2◦ Higher SOA than in most previous studies (100-119 Tg/a)◦ Monoterpenes : 20 Tg/a ◦ Water uptake significantly increases SOA◦ Agreement over US: reasonable, but underestimations in
winterStill wide spread in SOA for global models
Thank you for your Thank you for your attention!attention!
α-pinene + O3 and pinonaldehyde chemistry