1. Aerosol Simulation Over North America Aaron Van Donkelaar April 2005

2. Remote Sensing of Surface Particulate Matter M –mass loading M –mass loading ρ – particle mass density ρ – particle mass density r – effective radius (AERONET) r – effective radius (AERONET) τ – aerosol optical depth (MODIS/GEOS-CHEM) τ – aerosol optical depth (MODIS/GEOS-CHEM) Q ext – extinction factor (AERONET) Q ext – extinction factor (AERONET) Z – air mass height (GEOS-CHEM) Z – air mass height (GEOS-CHEM)

3. GEOS-CHEM Underestimates AOD MODIS, July 2002 GEOS-CHEM v7-02-01, July 2002 Optical Depth at 550nm [unitless] AERONET, July 2002

4. GEOS-CHEM Organic Carbon Too Low GEOS-CHEM v7-02-01 Mass Concentrations [ug/m 3 ] July 2002 IMPROVE Mass Concentrations [ug/m 3 ] July 2002

5. Summer Organic Carbon Bias GEOS-CHEM – IMPROVE [ug/m 3 ] May, 2002 June, 2002 September, 2002 April, 2002 July, 2002 August, 2002

6. Low OC Yield from Isoprene Matsunaga, S. N. et al. Isoprene oxidation products are a significant atmospheric aerosol component. in prep. Matsunaga, S. N. et al. Isoprene oxidation products are a significant atmospheric aerosol component. in prep. Claeys, M. et al. Formation of secondary organic aerosols from isoprene and its gas-phase oxidation products through reaction with hydrogen peroxide. Atmospheric Environment. Claeys, M. et al. Formation of secondary organic aerosols from isoprene and its gas-phase oxidation products through reaction with hydrogen peroxide. Atmospheric Environment. Claeys, M. et al. Formation of Secondary Organic Aerosols Through Photooxidation of Isoprene. Science. Claeys, M. et al. Formation of Secondary Organic Aerosols Through Photooxidation of Isoprene. Science. Recent literature has proposed OC yield from isoprene Guenther has suggested specific pathways Assume 1% to 3% Yield

7. OC from Isoprene Corrected Bias -remaining bias from biomass burning regions GEOS-CHEM – IMPROVE [ug/m 3 ] April, 2002May, 2002 June, 2002 July, 2002 August, 2002 September, 2002

8. OC Does Not Correct AOD Bias MODIS, July 2002 GEOS-CHEM w Isoprene Yield, July 2002 Optical Depth at 550nm [unitless] AERONET, July 2002

9. Preliminary Vertical Structure Evaluation - ICARTT NH 4 NO 3 OC SO 4 GEOS-CHEM PILS AMS

10. Summary Low yield OC production from isoprene corrects seasonal bias Low yield OC production from isoprene corrects seasonal bias Biomass burning inventories for 2002 are needed Biomass burning inventories for 2002 are needed Continue to evaluate model vertical structure using ICARTT data Continue to evaluate model vertical structure using ICARTT data

11. Acknowledgements Randall Martin Randall Martin Alex Guenther Alex Guenther Rokjin Park Rokjin Park Solene Turquety Solene Turquety Easan Drury Easan Drury