Biogenic Secondary Organic Aerosol Formation

Michael Boy

ASP / ACD / NCAR

What is the main process concerning SOA What is the main process concerning SOA formation ?formation ?

Nucleation !Condensational

growth !

We suggest that the growth of clusters to a detectable sice is restricted by the availability of condensable vapour. Observations of atmospheric particle formation and growth from a continental and a coastal site support this hypothesis, including that a growth process including ternary nucleation is likely to be responsible for the formation of CCN.

Kulmala et al., Nature 2000

M. Kulmala et at., Aerosol Science 35 (2004), p. 143-176

Where do we observe SOA formation ?

How many SOA formation events per year ?How many SOA formation events per year ?

Hyytiälä, Finland 1996 - 2003

0

20

40

60

80

100

120

140

1996 1997 1998 1999 2000 2001 2002 2003

Year

Nr.

of even

ts

Seasonal trend of SOA formation events ?

M. Kulmala et at., Aerosol Science 35 (2004), p. 143-176

Rural area in Finland

Rural area in Germany

Urban area in USA

Is SOA formation a local effect ?

(Stratmann et al.,

ACP 2003, Vol. 3)

(Stratmann et al., ACP 2003)

Vertical distribution of new formed particles

How fast do the new formed particles grow ?How fast do the new formed particles grow ?

Kulmala et at., Aerosol Science 2004, Vol. 35

Polar regions: 0.1 nm h-1

Coastal areas: 200 nm h-1

How many particles are produced per time ?

Urban areas:

up to 100 # cm-3 s-1

Coastal zones:

up to 104-105 # cm-3 s-1

Industrial plumes:

up to 104-105 # cm-3 s-1

________________________________________________________________________________________

University of Helsinki

3 nm

Free troposphere

Mixed layer

1 nm

Formation of TSCs

Formation of TSCs

Binary nucleation: H2SO4 + H2O

Ternary nucleation: H2SO4 + NH3 + H2O

Ion induced nucleation

Nucleation of organics

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University of Helsinki

3 nm

Free troposphere

Mixed layer

Production of condensable

vapours

Ozone

1 nm

Formation of TSCs

Production of condensable vapours

Sulphuric acid

Monotepenes reaction products

Sesquiterpenes reaction products

????

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University of Helsinki

3 nm

Free troposphere

Condensation

Coagulation

Deposition

Mixed layer

Production of condensable

vapours

Ozone

Condensation &Coagulation

1 nm

Formation of TSCs

Weber et al., JGR (1997) 102

Fiedler et al., ACPD (2005)

Sulfuric acid and nucleation mode particles ?

Date

Growth rate GR(H2SO4)

DMPS H2SO4 / GR(DMPS)

[nm h-1 ] [nm h-1 ] [%]

19.3.2003 1,0 0,06 6,1

20.3.2003 1,5 0,15 10,2

21.3.2003 2,6 0,24 9,1

25.3.2003 2,5 0,15 6,1

26.3.2003 3,6 0,31 8,6

29.3.2003 3,6 0,17 4,8

31.3.2003 3,5 0,23 6,7

2.4.2003 2,4 0,40 16,9

3.4.2003 3,8 0,28 7,3

6.4.2003 1,8 0,16 8,7

7.4.2003 2,9 0,39 13,5

Average 2,7 0,2 8,9

Intermedia step for global models

Influence on CCN

UHMA (University of

Helsinki Multicomponent

Aerosol code)Chemistry subroutine

(67 species)

BLMARC

(1-dimensionsal model)

Emission scheme for different biospheres

Extended organic chemistry scheme

Condensation of organics

Information on the secrets

of SOA formation

Ion induced nucleation

1-D-Model trajectory

Thanks !!!