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
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
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
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
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
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
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
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
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
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
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