1. Long-Range Transport of Sulfate to Canada GEOS-Chem Users Meeting Aaron van Donkelaar Dalhousie University April, 2007

2. SO 2 emission inventories out of date Inventories used by GEOS-Chem Global Inventories –GEIA (1985) –EDGAR (2000) Regional Inventories –Bravo (Mexico, 1999) –Streets (East Asia, 2000) –NEI99 (USA, 1999) NEI99 BRAVO Streets

3. Generation of Scale Factors Scale factors are used to approximate emission changes from the base year of the inventories. Regulated: limit pollutant emission (i.e. SO x, NO x, CO) USA, Canada, Europe, Japan, etc. Generate emission reports –EPA Acid Rain Program –The Canada-Wide Acid Rain Strategy –European Monitoring and Evaluation Program (EMEP) Unregulated: no emission controls Asia, Africa, etc. Must infer emissions changes from secondary sources, such as CDIAC CO 2 emissions. –NO x : total CO 2 –CO: liquid CO 2 –SO x : solid CO 2

4. SO x Emissions Scalar (2000-2002)

5. INTEX-B Intercontinental Chemical Transport Experiment - Phase B –April/May 2006 Study influx of Asian pollution to North America Canadian Instrumentation: –Cessna 207 Aircraft (Leaitch) 33 Flights AMS, O 3, CO –Lidar (Duck) –Whistler Peak Measurements (MacDonald) AMS, O 3, CO, Filter Pack

6. GEOS-Chem successfully represents Cessna SO 4 = over Whistler Aerosol size limit not present in GEOS-Chem –Scale AMS SO 4 = by average MOUDI impactor size factor (~1.4) –No scaling applied to organics or nitrate –Mean GEOS-Chem SO 4 = bias of +0.17 ug/m 3 From Rupakheti et al., 2005 G-C (dotted) Cessna (solid) Sulfate Organics Nitrate

7. GEOS-Chem biased compared to DC-8 SO 4 = Different sampling times and size cutoffs –Filter Pack long sample ~4 um cutoff GC mean bias of +0.57 [ug/m 3 ] –Mist Chamber 1 min. sample ~1 um cutoff GC mean bias of +0.75 [ug/m 3 ] Filter Pack vs. Mist Chamber –32% increase in mean model bias –role of size cutoff?

8. Averaged between 700 and 900 mb,filtered as Hudman et al., in press GEOS-Chem mean bias of ~+4 ppt SO 2 measurements are well-captured above 900 mb DC-8 GEOS-Chem Pressure [mb] SO 2 [ppt]

9. GEOS-Chem SO 2 columns low relative to OMI SO 2 [DU] OMI GEOS-Chem SO 2 [DU]

10. Sulfate is a large component of AOD As noted by Heald et al., 2006, GEOS-Chem total AOD over pacific is low during spring AOD bias may represent underestimate in SO 2 emissions or effects related to assumed size distribution GEOS-Chem MODIS AOD GEOS-Chem % AOD from SO 4 = AOD MODIS GEOS-Chem

11. Influence of Asian sulfate on Canada SO 4 = 600 mb Altitude [km] Altitude [km] SO 4 = [ug/m 3 ] % Asian SO 4 = Significant portion of SO 4 = over western Canada is of southeast Asian origin Eastern pollution largely north American sources Sulfur typically transported as SO 4 =

12. Questions This research has been produced by the collaborative efforts of: Randall Martin Dalhousie University / Harvard-Smithsonian Center for Astrophysics Thomas Walker Dalhousie University Richard Leaitch, Anne Marie Macdonald, and Peter Liu Environment Canada Nickolay Krotkov Goddard Earth Sciences and Technology Center Jack Dibb University of New Hampshire Greg Huey Georgia Institute of Technology This work was supported by the National Sciences and Engineering Research Council of Canada Special Research Opportunity program.

13. References Brock, C., A., P. K. Hudson, E. R. Lovejoy, A. Sullivan, J. B. Nowak, L. G. Huey, O. R. Cooper, D. J. Cziczo, J. de Gouw, F. C. Fehsenfeld, J. S. Holloway, G. Hübler, B. G. Lafleur, D. M. Murphy, J. A. Neuman, D. K. Nicks, D. A. Orsini, D. D. Parish, T. B. Ryerson, D. J. Tanner, C. Varneke, R. J. Weber, and J. C. Wilson, Particle characteristics following cloud-modified transport from Asia to North America. Journal of Geophysical Research, 109, D23S26, doi: 10.1029/2003JD004198, 2004. Heald, C. L., D. J. Jacob, R. J. Park, B. Alexander, T. D. Fairlie, R. M. Yantosca, and D. A. Chu, Transpacific transport of Asian anthropogenic aerosols and its impact on surface air quality in the United States. Journal of Geophysical Research, 111, D14310, doi:10.1029/2005JD006847, 2006. Hudman, R. C., D. J. Jacob, S. Turquety, E. M. Leibensperger, L. T. Murray, S. Wu, A. B. Gilliland, M. Avery, T. H. Bertram, W. Brune, R. C. Cohen, J. E. Dibb, F. M. Flocke, A. Fried, J. Holloway, J. A. Neumann, R. Orville, A. Perring, X. Ren, G. W. Sachse, H. B. Singh, A. Swanson, P. J. Wooldridge, Surface and lightning sources of nitrogen oxides over the United States: magnitudes, chemical evolution, and outflow. Journal of Geophysical Research, in press. Rupakheti, M., R. W. Leaitch, U. Lohmann, K. Hayden, P. Brickell, G. Lu, S.-M. Li, D. Toom- Sauntry, J. W. Bottenheim, J. R. Brook, R. Vet, J. T. Jayne, and D. R. Worsnop, An intensive study of the size and composition of submicron atmospheric aerosols at a rural site in Ontario, Canada. Aerosol Science and Technology, 39, 722-736, 2005.