1. Atmospheric Aerosols R.B. Husar, Washinton University HTAP Meeting, June 10, 2008, Washington DC

2. Dimensions of Gaseous Pollutants: X, Y, Z, T Dimensions of Aerosols: Particle Size, Composition, Shape

4. Phase II HTAP Goal: Integration of Emissions, Models and Observations

5. Aerosols are Indicators of Many Earth System Processes Including Human-induced Perturbations Volcanoes Dust storms Fires Anthropogenic Pollution EPA NAAQS PM2.5, O3 Exceptional Event Rule Exclusion of data when it is strongly influenced by “exceptional events" (EE), such as smoke from wildfires or windblown dust or LRTP.

8. Continental Surface Visibility (7000+ Human Observers) Low Visibility High Visibility

9. Continental Surface Extinction Coefficient Climatology Dec, Jan, Feb Jun, Jul, Aug Sep, Oct, Nov Mar, Apr, May India Husar et al, 2000

12. Everglades, FL Big Bend, TX G. Smoky Mtn. Sahara Dust - July Mex. Smoke-May

13. Emission: Green Modeling: Green Observations: Green

14. Emission: Yellow Modeling: Yellow Observations: Yellow

16. Central American Smoke Plume Surface PM2.5 Ozone

17. Kansas Agricultural Smoke, April 12, 2003 Fire Pixels Organics 35 ug/m3 max Ag Fires SeaWiFS, Refl Smoke Emission April 11: 87 T/day April 10: 1240 T/d Assuming Mass Extinction Efficiency: 5 m 2 /g

18. Emission: Red Modeling: Yellow Observations: Yellow

19. Aerosol Nitrate Anomaly – Every 3 Days

20. Seasonal PM25 by Region Sulfate-driven Jul-Aug peak Feb-Mar peak, of unknown origin

22. Origin of Fine Dust Events over the US Gobi dust in spring Sahara in summer Fine dust events over the US are mainly from intercontinental transport

24. Supporting Evidence: Transport Analysis Satellite data (e.g. SeaWiFS) show Sahara Dust reaching Gulf of Mexico and entering the continent. The air masses arrive to Big Bend, TX form the east (July) and from the west (April)

25. Sahara PM Events over the Eastern US PM10 July 5, 1992 PM10 June 21, 1997 PM10 June 30 1993 Sahara Dust Sahara Dust TOMS, July Aerosol Index

26. Asian Dust Cloud over N. America On April 27, the dust cloud arrived in North America. Regional average PM10 concentrations increased to 65  g/m 3 In Washington State, PM10 concentrations exceeded 100  g/m 3 Asian Dust 100  g/m 3 Hourly PM10

27. ~50% of the variability in springtime PM 2.5 in the Western U.S. can be explained by changes in Asian dust (Fischer et al., 2008)

28. EPISODIC EPISODIC EPISODIC … episodic emissions require emission-observation-model integration…