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Illumination Dependent Aerosol Optical Properties

Explore the intricate details of radiance and visibility in the atmosphere, including the equilibrium radiance, path radiance, and contrast sensitivity. Learn how aerosol optical properties affect visibility metrics and illumination effects.

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Illumination Dependent Aerosol Optical Properties

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  1. Illumination Dependent Aerosol Optical Properties • Volume scattering function • Path function • Path radiance • Atmospheric modulation transfer function

  2. Radiation Transfer Equation loss gain

  3. Equilibrium Radiance When Nr has some special value, Nq, such that bextNq= , then dNq/dr = 0. Nq is independent of r and is commonly referred to as the equilibrium radiance.

  4. Radiance Difference If Nq is constant, the previous equation can be integrated to yield where

  5. Path Radiance Rearranging yields The second term is the path radiance (airlight), , which results from scattering processes throughout the sight path. The parameter is the sky radiance

  6. Path Radiance Approximation If T is approximately zero, then Nq= =Ns (sky radiance) and:

  7. In general:

  8. Radiance Difference and Real World . .

  9. Apparent and Inherent Contrast Define: Apparent Contrast: Inherent Contrast:

  10. Radiance Difference Transmittance

  11. Contrast Transmittance

  12. If background is sky then: and

  13. Estimating Extinction If background is sky, Ns: and, which yields

  14. The Visual Range Concept The distance at which Cr approaches a threshold contrast of between -0.02 or -0.05 defines the visual range, Vr. If Co= 1 (black object) and -0.02 is taken to be a threshold contrast, then the previous equation becomes

  15. Visibility Metrics • Apparent contrast: Cr = Coe-bextr • Visual Range: vr = 3.912/ bext • decView: dv = 10 ln(bext/.01)

  16. Contrast Sensitivity Surface (back)

  17. Contrast Sensitivity Surface (forward)

  18. Forward Scattering

  19. Back Scattering

  20. Optics of Visibility

  21. La Sals –Forward Scattering

  22. La Sals – Backward Scattering

  23. La Sals -- 30km

  24. Mt Trumbull -- 130km Mt Trumbull -- 130km

  25. North Rim of Grand Canyon Through Smoke Plume

  26. Easterly View of Grand Canyon from Desert View Watch Tower

  27. Westerly View from Desert View Watch Tower

  28. Clouds Evaporate Leaving Sulfate Haze

  29. Clouds Evaporated Leaving Sulfate Haze

  30. Sulfate Haze Trapped Below Rim

  31. Next Day After Haze is Blown Out

  32. Path Radiance Absent Because of Clouds

  33. Nitrogen Dioxide Haze

  34. Nitrogen Dioxide Plume

  35. Illumination Effects

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