1. Illumination Independent Aerosol Optical Properties n Extinction Scattering Absorption n Volume scattering function (phase) n Transmittance

2. The extinction coefficient is made up of particle and gas scattering and absorption: where s, a, g, and p refer to scattering, absorption, gases, and particles, respectively. Extinction =

3. Components of Scattering and Extinction

4. Animations of scattering and absorption

5. One Approximation for Estimating b ext

6. where E e is mass extinction efficiency, f i (x) is the aerosol mass distribution dm/dx of the ith species, x=ln[D/Do], and λ is the wavelength. Extinction as Function of Size

7. where and for multiple species Externally Mixed Model

8. Scattering Efficiency (Q)

9. Single Particle Efficiency

10. Particle Size Distribution

11. Scattering Efficiency as Function of Size

12. Carbon Extinction Efficiency

13. Phase Function for Soil and Sulfate

14. Phase Function for Carbon

15. Forward and Backward Scattering

16. Pollutant Species

17. Primary vs. Secondary Particles and Gases (Pollutants) n Primary particles and gases are those emitted into the atmosphere directly from some source. n Secondary particles and gases are formed in the atmosphere by chemical reactions, by condensation growth, and/or by coagulation.

19. Particle Size Distribution

20. Sources of Primary Particles Anthropogenic n Wind Blown Dust Roads, Over Grazing, Farming practices, Mining n Biomass Burning Land Clearing Practices n Emissions from fossil fuel combustion Fly Ash Condensation of Hot Vapors Naturally Occurring n Wind Blown Dust Deserts n Volcanoes n Fires n Plant Particles (pollen) n Sea Salt Spray (NaCl)

21. Sources of Primary Gases Important to Secondary Particle Formation CompoundAnthropogenicNaturally Occurring SO 2 Fossil-Fuel Smelters Oil Refining Volcanoes NO x Fossil-Fuel Combustion Mobil Sources Soil Release (Fertilizer) Soil Release Lightning NH 3 Farm Animals Wild Animals Vegetation Ocean Volatile Organics Mobile SourcesVegetation

23. Hygroscopic Aerosols n Water uptake by particles in the atmosphere n Aerosol particles grow and scatter more light n Deliquescence - the RH value at which the crystal begins to absorb water and becomes a solution droplet n Hysteresis - water is retained on the particle at RH values lower than predicted by equilibrium

24. Growth of Sulfate

25. Hygroscopic Growth of Particles

26. Ammonium Sulfate D/D o Curves

27. Two Measured f(RH) Curves and Theoretical Estimated

28. F(rh) for Grand Canyon

29. Estimated f(rh) for Sulfate and Organics

30. Internally Mixed Aerosol however,

31. Mass Removal Issues

32. From previous equations, it is apparent that changes in visibility that correspond to changes in aerosol species concentrations can be expressed by forming the derivative  τ r /  C i, where C i refers to the concentration of particulate species i, and that this derivative will have terms containing the derivative  b ext /  C i. Therefore, define partial scattering efficiency as: Partial Scattering Efficiency

33. Extinction for External and Internal Mixture

34. D/D o Curves for Partial Scattering Calculation

35. Partial Scattering Efficiency for External and Internally Mixed Aerosols