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The Effect of Climate Change on Secondary Organic Aerosols

The Effect of Climate Change on Secondary Organic Aerosols. Havala Olson Taylor Pye April 11, 2007 Seinfeld Group Department of Chemical Engineering California Institute of Technology. Outline. Introduction Model and Simulation Description Predicted Present Day SOA Concentrations

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The Effect of Climate Change on Secondary Organic Aerosols

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  1. The Effect of Climate Change on Secondary Organic Aerosols Havala Olson Taylor Pye April 11, 2007 Seinfeld Group Department of Chemical Engineering California Institute of Technology

  2. Outline • Introduction • Model and Simulation Description • Predicted Present Day SOA Concentrations • The Effect of Climate Change on SOA • Conclusions

  3. Introduction Organic 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

  4. Model and Meteorological Field Description Approach 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

  5. Equilibrium Partitioning Production from oxidation of gas phase precursors SOA SOG Dry deposition Dry deposition Wet deposition Wet deposition SOA Model

  6. HC + Ox α1G1 + α2G2 A1 A2 SOA Model SOA is represented using a two (or one) product model: Parameters obtained from laboratory experiments: αi , KOM,i [Chung and Seinfeld, 2002; Pankow, 1994]

  7. SOA Precursors

  8. Biogenic Emission Scheme Emissions are potentially influenced by climate through temperature and changes in light received at the surface E = EO CT CL • Isoprene (VI): • CL depends on column cloud cover • Monoterpenes (I-IV): • No light dependence • ORVOC (I, IV, V): • CL independent of climate change • No T dependence [Guenther et al., 1995]

  9. Predicted Present Day SOA Concentrations DJF MAM JJA SON

  10. Predicted Present Day SOA Concentrations: The U. S. MAM DJF JJA SON

  11. The Effect of Climate Change on SOA

  12. The Effect of Temperature on Biogenic Emissions Isoprene emissions increase 24% Monoterpene emissions increase 20%

  13. Changes in SOA Surface Concentrations

  14. 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)

  15. Changes in SOA as a Function of Altitude

  16. 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 SOA from sesquiterpenes

  17. 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

  18. 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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