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Updated: Jun 9, 2026
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Summary
A long-term study found a significant decrease in large atmospheric particles west of Boston since 1975. This decline in giant particles contrasts with stable total suspended particulates in urban areas, suggesting localized atmospheric changes.
Area of Science:
- Atmospheric Science
- Aerosol Physics
- Optical Remote Sensing
Background:
- Long-term solar aureole brightness observations since 1975 west of Boston.
- Observed significant decrease in solar aureole brightness.
- Contrasting trends in giant particle concentrations versus total suspended particulates in urban areas.
Purpose of the Study:
- Investigate the relationship between forward scattering and aerosol mass distribution, specifically the coarse fraction (CF).
- Develop a method to adjust scattering functions from plane-wave sources to account for the actual, limb-darkened Sun.
- Analyze the impact of aerosol properties on light scattering and extinction.
Main Methods:
- Analysis of solar aureole brightness data collected over decades.
- Computational modeling of light scattering by aerosols.
- Calculation of wavelength dependence of extinction.
- Modification of scattering functions for a limb-darkened Sun.
Main Results:
- Evidence for the virtual disappearance of giant particles (>~10 micrometers) in the lower atmosphere west of Boston.
- Calculations reveal sensitivity of forward scattering to aerosol mass distribution.
- Wavelength dependence of extinction is less affected by the coarse fraction but sensitive to smaller particle size distributions (<0.4 and ~0.6 micrometers).
Conclusions:
- Localized atmospheric changes, particularly the reduction of giant particles, significantly impact solar aureole brightness.
- Aerosol size distribution, especially smaller particles, plays a crucial role in light scattering and extinction.
- The study provides insights into aerosol-atmosphere interactions and optical phenomena.
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