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