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Vertical Characterization of Aerosol using Aeronet

Utilizing Aeronet to analyze aerosol layers, distinguishing between surface, tropospheric, and stratospheric components. Extracting data from specific Pacific sites, plotting wavelengths, and solving for aerosol parameters. Future implications for satellite validation and global analysis.

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Vertical Characterization of Aerosol using Aeronet

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  1. Vertical Characterization of Aerosol using Aeronet

  2. Purpose • To separate surface, troposphere and stratospheric aerosol components

  3. Background Aeronet – Instrument Desc • Aeronet is a sun photometer focuses on the sun • It measures x wavelengths • Knowing the solar constant at the top of the atmosphere, Aeronet takes the difference to find AOT and x wavelengths. • Aeronet was put into place by NASA as a way to validate satellite AOT measurements.

  4. Aeronet Sites with Data

  5. Method • Pick Aeronet sites in Pacific where there isn’t a lot of pollution • Extract three wavelengths (380, 500, 675) and plot • We assume that the only components in the pacific column are sea salt at the surface and the additional is from the troposphere. • AOT Surf + AOT Trop = AOT Tot

  6. Angstrom Exponent • The other information we have about the aerosol is the angstrom exponent • Bext = C(Lambda)^-A • A= - ln(Tau1/Tau2)/ln(wavelength 1/wavelength 2) • A is the slope between two wavelengths and indicates the color of the aerosol • For the pacific island sites we made the assumption that the surface angstrom exponent = 0 and that the troposphere would have a constant A

  7. 6 Equations/ 6 Unknowns • We have six unknowns, AOT Surf and Trop for 380, 500 and 675 • We know that AOT surf + AOT trop = AOT tot • This gives us 3 equations • Since the AngsExponent on the surf is 0 we can say that AOTsurf 380 = AOTsurf 500= AOTsurf 675 • This gives us 2 independent equations AOT380=AOT 500 and AOT380 = AOT 675

  8. Last Equation • At the peak we assume a surface AOT and then calculate the tropospheric AOT and the trop Angstrom Exponent • We assume that Angs Exponent is fixed in the troposphere, so then we can substitute and solve for Surf AOT 380 • We then get two curves – Surf and trop • We iterate to find the best sea salt concentration

  9. Stratosophere • Using this same method, we extracted the stratosphere from the troposphere at Mauna Loa • Assume that the stratosphere has a constant slope. • Assume it is constant over the entire world.

  10. Future work: • Once we’ve separated the surface and the troposphere components we can subtract this troposphere from other sites in the same latitude belt • Also – when we have validated the MODIS and MISR AOT with aeronet we will be able to make this same subtraction from the satellite and characterize AOT both horizontally and vertically

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