Havala Olson Taylor Pye
April 11, 2007Seinfeld GroupDepartment of Chemical EngineeringCalifornia Institute of Technology
The Effect of Climate Change on Secondary Organic Aerosols
Outline
Introduction
Model and Simulation Description
Predicted Present Day SOA Concentrations
The Effect of Climate Change on SOA
Conclusions
IntroductionOrganic aerosol consists of Primary Organic Aerosol (POA) Secondary Organic Aerosol (SOA)
SOA in GEOS-Chem is of biogenic origin and potentially influenced by changes in
Temperature (affects partitioning and precursor emission rates)
Precipitation and atmospheric stability Transport Gas phase chemistry (such as oxidant levels)
Objective: Determine the effect of climate change on SOA
Model and Meteorological Field DescriptionApproach for examining the effect of climate change on SOA: Simulate present day (1999-2001) aerosol (sulfate, nitrate,
ammonium, sea salt, black carbon, organic carbon) levels Meteorology from GISS GCM III Simulations with GEOS-Chem v.7-04-05 (full chemistry)
Simulate future (2049-2051) aerosol levels Meteorology from GISS GCM with CO2 emissions following IPCC
A1B scenario Simulations with GEOS-Chem assume anthropogenic emissions
remain at present day levels
The meteorology of the future [Wu et al. in preparation 2007]
522 ppm CO2 in 2050 1.7 K global mean surface temperature rise 8% increase in global annual mean precipitation
SOA Model
SOAProduction from oxidation of gas phase precursors
SOGEquilibrium Partitioning
Wet deposition
Dry deposition
Wet deposition
Dry deposition
SOA is represented using a
two (or one) product model:
Parameters obtained from laboratory experiments: αi , KOM,i
SOA Model
HC + Ox α1G1 + α2G2
A1 A2 Oi
iiOM MG
AK
][
][,
O
i
OOiOMiOM TTR
H
T
TTKTK
11exp)()( ,,
i
iO APOAM ][][
[Chung and Seinfeld, 2002; Pankow, 1994]
SOA Precursors
Parent VOC categories treated by GEOS-Chem
(I) ALPH: α-pinene, β-pinene, sabinene, careen, terpenoid ketones(II) LIMO: limonene(III) TERP: α-terpinene, γ-terpinene, terpinolene(IV) ALCO: myrcene, terpenoid alcohols, ocimene(V) SESQ: sesquiterpenes(VI) ISOP: isoprene
Biogenic Emission SchemeEmissions are potentially influenced by climate through
temperature and changes in light received at the surface
Monoterpenes (I-IV): No light dependence
ORVOC (I, IV, V): CL independent of climate
change No T dependence
Isoprene (VI): CL depends on column cloud
cover
E = EO CT CL
[Guenther et al., 1995]
Predicted Present Day SOA Concentrations
DJF MAM
JJA SON
Predicted Present Day SOA Concentrations: The U. S.
DJF MAM
JJA SON
The Effect of
Climate Change on SOA
The Effect of Temperature on Biogenic Emissions
Isoprene emissions increase 24%
Monoterpene emissions increase 20%
SOA category
Contributing Emissions
Present Day
FuturePercent Change
Tg/yr Tg/yr
ALPHMonoterpenes,
ORVOC 111 131 18%
LIMO Monoterpenes 34 40 20%
TERP Monoterpenes 4 5 20%
ALCOMonoterpenes,
ORVOC 40 42 5%
SESQ ORVOC 15 15 0%
ISOP Isoprene 505 629 24%
Changes in SOA Surface Concentrations
Changes in SON Surface Concentrations (preliminary analysis) Significant decreases likely correspond to moderate temperature
increases coupled with strong increases in precipitation Increases in surface concentrations likely correspond to
strong temperature increases or moderate temperature increases coupled with reduced rainfall
(except for possibly S. America)
Changes in SOA as a Function of Altitude
The Effect of Climate Change on
SOA Global Burdens Climate change does not significantly affect the global SOA burden
The burden decreases if biogenic emissions do not increase
burdenwet
depositionnet
production
dry depositio
n
Tg Tg/yr Tg/yr Tg/yr
present 0.44 -14 17 -3
future 0.45 -16 19 -3
burdenwet
deposition
net productio
n
dry depositio
n
Tg Tg/yr Tg/yr Tg/yr
present 0.020 -0.98 1.21 -0.23
future 0.016 -0.95 1.17 -0.23
SOA from sesquiterpenes
Conclusions Higher temperatures in the future result in higher
biogenic emissions
In general, surface SOA concentrations are elevated in the future due to increased precursor emissions
Increased precipitation may cause decreased surface concentrations
Concentrations of SOA in the upper troposphere are typically lower in the future
Despite changes in concentrations, the SOA global burden remains constant with 2000—2050 climate change
Acknowledgements
Meteorological fields were provided by Loretta Mickley. Useful discussions with Shiliang Wu and Hong Liao are greatly appreciated. This material is based upon work supported under a National Science Foundation Graduate Research Fellowship.
References: Chung, S. H. and J. H. Seinfeld (2002), Global distribution and climate forcing of
carbonaceous aerosols, J. Geophys. Res., 107, D19, 4407. Guenther, A., et al. (1995), A global model of natural volatile organic compound
emissions, J. Geophys. Res., 100, D5, 8873-8892. Pankow, J. F. (1994), An absorption model of gas/particle partitioning of organic
compounds in the atmosphere, Atmos. Environ., 28, 185-188. Wu, S., L. J. Mickley, D. J. Jacob, D. Rind, and D. G. Streets (2007), Effect of 2000-
2050 global change on ozone air quality in the United States, in preparation .
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