Light Scattering by Aerosols, Droplets, and Ice Crystals

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Light Scattering by Aerosols, Droplets, and Ice
Crystals
Piotr J. Flatau University of California, San
Diego Scripps Institution of Oceanography Based
on presentation by Bill Malm
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Why light extinction?

• Basis for majority of remote sensing techniques
  passive and active. Retrievals of water vapor,
  cloud water, temperature soundings
• Basis for climate estimates of interaction of
  radiation with our atmosphere

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Optical phenomena Concepts of Geometric Optics
and Monte Carlo

• Ray-tracing (geometric optics)
• Monte-Carlo simulations of many photons
  interacting with particles this is what nature
  does.

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(No Transcript)
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Aerosol transport

• Sulphate conversion
• Transport

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Size Comparison
Animation cyclone
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Electromagnetic Spectrum
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Pollutant Species
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Particle Size Distribution
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Basic Interactions of Solar Radiation with
Aerosols

• Extinction
• Scattering (deflection of light)
• Absorption conversion to heat
• Animaton (interactions)
• Animation (scattering)

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Extinction
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.
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Extinction as Function of Size
where Ee is mass extinction efficiency, f i(x) is
the aerosol mass distribution dm/dx of the ith
species, xlnD/Do, and ? is the wavelength.
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Scattering Efficiency (Q)
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Scattering Efficiency as Function of Size
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Carbon Extinction Efficiency
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Phase Function for Soil and Sulfate
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Forward and Backward Scattering
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Phase Function for Carbon
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Animations
Animations (size)
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Components of Scattering and Extinction
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Summary

• Interaction of light with matter forms basis for
  estimation of climate-radiation feedbacks and
  remote sensing.
• Single scattering albedo, and phase function are
  the most important radiative characteristics of a
  particle.