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Maud Leriche, Laurent Deguillaume, Nadine Chaumerliac, Wolfram Wobrock, Karine Sellegri
Multiphase cloud chemistry Multiphase cloud chemistry modeling: gas versus particle modeling: gas versus particle
phasesphases
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Aerosols/cloud/Aerosols/cloud/chemistry chemistry
interactionsinteractions
CCN
Sources
Incident solar radiation
IR radiation
Aerosols
Precursors
DIRECTEFFECT
Vertical transport
Chemical reactions
Chemical reactions
Evaporation
ActivationActivation
Wet deposition
Wet deposition
Evaporation
INDIRECTEFFECT
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StrategyStrategy
Puy de Dôme site, center of France
Classification according to air mass type and cloud type
Typical scenarios
Process model M2C2Model of Multiphase Cloud Chemistry
Physico-chemical
properties of aerosols
Microphysical properties of
clouds
Physico-chemical properties of aerosolsMicrophysical and chemical properties of
clouds
Role of chemistry
Nucleation capacityNucleation capacity HygroscopicityHygroscopicity
Precipitating capacityPrecipitating capacity
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M2C2 model: Model of M2C2 model: Model of Multiphase Cloud Multiphase Cloud
ChemistryChemistry
rainrain
GASGAS
cloudcloud
AEROSOLSAEROSOLS
NucleationNucleation
Collision/coalescenceCollision/coalescence
Condensation/EvaporationCondensation/Evaporation
Sedimentation Sedimentation
Dynamical framework: air parcel
Leriche et al., 2001 ; Curier, 2003
Microphysics: quasi-spectral scheme, log-normal distributions
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M2C2 model: Model of M2C2 model: Model of Multiphase Cloud Multiphase Cloud
ChemistryChemistry
Leriche et al., 2003 ; Deguillaume et al., 2004
Explicit chemical mechanism valid for any environmentAqueous phase: chemistry of HxOy, of chlorine, of carbonates, of NOy, of sulfur, oxidation of VOCs, chemistry of transition metals (iron, copper, manganese)
Air/droplet exchange: mass transfer kinetic theory (Schwartz, 1986)
pH : calculated at each time step by solving the electroneutrality equation
aqeff
tgtggg
gC
RTH
kCLkCDP
dt
dC
aqeff
tgtaqaqaq
aqC
RTH
kCLkCDP
dt
dC
Mathematical formulation
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Case study: polluted Case study: polluted wintertime air mass at Puy de wintertime air mass at Puy de
Dôme siteDôme site
8 0 0
1 0 0 0
1 2 0 0
1 4 0 0
1 6 0 0
Alti
tude
(m
)
T h e 1 3 th o f D e c e m b e r 1 9 9 7
1 2 4 1 2 8 1 3 2Y (k m )
-2
-1
0
1
2
vertical wind (m
/s)
B ac k -tra je c to ryv ertic a l w in d
Beginning of air parcel ascension
3D simulation of meteorological situation on Puy de Dôme area
the 13th of December 1997 using meso-scale Clark model
Dynamical initialization
Dynamical trajectory
The air parcel follows the dynamical back-trajectory, which
reaches the Puy de Dôme at 12.11 p.m.
Chemical initializationGas phase: available measurementsAqueous phase: chemical soluble species coming from aerosol activation
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Mode 3
BC OC NO3 SO4 NH4 OI OA H2O nd
Mode 1
Mode 2
Sellegri et al., 2003
chemical compositionAerosol initialization
Mode Napi (cm-3) R0i (µm) logi
1 95,5 0,025 0,079
2 1921 0,066 0,279
3 530,3 0,132 0,204
NO3- (%) NH4
+ (%) SO42- (%)
12 9 4
10 10 11
18 15 37
0 .0 1 0 .1 1R ay o n (µ m )
0
4 0 0
8 0 0
1 2 0 0
1 6 0 0
dN/d
logD
(#.
cm-3
)
microphysical parameters
1
2
3
Case study: polluted Case study: polluted wintertime air mass at Puy de wintertime air mass at Puy de
Dôme siteDôme site
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Aerosol activationAerosol activation
Important activation at the beginning: 700 cm-3
No significant activation afterwards < 1 cm-3
Evolution of DCmoy and LWC by condensation/evaporation following ascent and descent
of the parcel
1 2 :0 0 1 2 :0 2 1 2 :0 4 1 2 :0 7 1 2 :0 9 1 2 :11tim e (h o u rs)
0
2
4
6
8
1 0
1 2
Mea
n cl
oud
diam
eter
(µ
m)
0
0 .1
0 .2
0 .3
0 .4
0 .5
Liquid w
ater content (g.m-3)
D C m o yL W C
1 2 :0 0 1 2 :0 2 1 2 :0 4 1 2 :0 7 1 2 :0 9 1 2 :11tim e (h o u rs)
1 x 1 0 -4
1 x 1 0 -3
1 x 1 0 -2
1 x 1 0 -1
1 x 1 0 0
1 x 1 0 1
1 x 1 0 2
1 x 1 0 3
Num
ber
of a
ctiv
ated
aer
osol
s (#
.cm
-3)
0
0 .0 0 1
0 .0 0 2
0 .0 0 3
0 .0 0 4
Supersaturation
n ew d ro p le tssu p e rsa tu ra tio n
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Aerosol activationAerosol activationEvolution of aerosol mass distribution
Most important activation at the beginning
Largest particles activated
Spectrum moves towards small diameters at the
beginning
Distribution initiale
0 .0 1 0 .1 1 1 0 1 0 0D ia m è tre (µ m )
0 x 1 0 0
2 x 1 0 -1 0
4 x 1 0 -1 0
6 x 1 0 -1 0
dM/d
logD
(kg
.cm
-3)
Initial distribution
6x10-10
0 .0 1 0 .1 1 1 0 1 0 0D iam ete r (µ m )
0 .0 x 1 0 0
4 .0 x 1 0 -1 3
8 .0 x 1 0 -1 3
1 .2 x 1 0 -1 2
1 .6 x 1 0 -1 2
dM/d
logD
(kg
.cm
-3)
1.6x10-12
t0 + 2 mns
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Sources of chemical Sources of chemical species in cloudspecies in cloud
originspecies chemistryaerosols
[SO42-]
[NH4+]
[NO3-]
65% 35%
50%
90% 10%
50%
Initialization of gas phaseNH4+
Chemical production in aqueous phase : HSO3- + HNO4
Initialization of gas phase
Chemical production in gas phase : NO2 + OH
Chemical production in aqueous phase: HSO3- + HNO4SO4
2-
NO3-
27%
23%
1st nucleation event Initialization of droplet chemical composition
[NO3-] = 2,2 10-4 M[NH4
+] = 1,9 10-4 M [SO42-] = 4,3 10-4 M
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Conclusion and Conclusion and PerspectivesPerspectives
method adapted to the study of aerosols/cloud/chemistry interactions
Aerosol activation Significant at the beginning
Initialization of the droplet chemical composition
Sources of chemical speciesAerosols most important sourceOthers : scavenging of gas and chemical reactivity
Classification of cloudy events at Puy de Dôme station
Generalization of results