Difference between revisions of "Satellite Measurements of Atmospheric Aerosols"
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==== Principles of Satellite Aerosol Detection==== | ==== Principles of Satellite Aerosol Detection==== | ||
| + | Two competing effects of aerosols are that the light scattering particles tend to add reflectance to the surface brightness and at the same time they act as a filter which exponentially diminishes the total upwelling radiation | ||
| + | |||
| + | The ratio P/R0 determines whether aerosols will increase or decrease the apparent reflectance | ||
| + | *R0=Surface reflectance function | ||
| + | |||
| + | AOT retrieval is not possible either when aerosol system reaches radiative equilibrium or when Phase function approximately matches surface reflectance function(which occur over bright surfaces) | ||
==== Challenges of Satellite Aerosol Remote Sensing==== | ==== Challenges of Satellite Aerosol Remote Sensing==== | ||
Revision as of 08:56, November 11, 2009
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Title: Satellite Measurements of Atmospheric Aerosols | Document Link
Organization/Author: R. Husar
Type: Other
Year: 2009
Region:
Observation Type:
Observation Needs:
Document Status: Unsubmitted, 2009/11/00"2009/11/00" contains a sequence that could not be interpreted against an available match matrix for date components.
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Description of Document: Book chapter for Aerosol Measurement
Chapter Table of Contents: Satellite Measurements of Atmospheric Aerosols
Introduction
- Two fields not clear from the start - 2 fields are atmospheric aerosols and remote sensing
- Aerosols are described by matching models and observations - uncertainty comes from divergence between model/uncertainty
- Two fields complement each other not replace
Aerosol Physical and Optical Properties
Aerosol Dimensions
- Space
- Time
- Diameter
- Composition
- Shape
- Mixing (internal/external)
Key point is that diameter, composition, shape and mixing are all integral from satellite perspective not just height
signal at TOA is weak compared to surface reflectance
Regularities allow simplify the :
- Multi-modal simplifies size distribution if you know mass
- Mass median diameter increases in Urban area increases concentration. Find mass median using spectral and angular scattering.
- For region there is a high correlation between total light scattering and mass concentration of fine particles
- aerosol types are in layers
- P = scattering phase function = energy scattered in given direction/average energy in all directions
- aerosol types have same forward scattering, satellite measures the backscatter, therefore total scattering can be calculated and then correlated to pm2.5 conc. for a region.
Satellite Orbits
GEO - Geostationary orbits; 36,000 km up. high temporal res, low spatial res Polar orbit - low temporal (pass 1x a day); high spatial res
Principles of Satellite Aerosol Detection
Two competing effects of aerosols are that the light scattering particles tend to add reflectance to the surface brightness and at the same time they act as a filter which exponentially diminishes the total upwelling radiation
The ratio P/R0 determines whether aerosols will increase or decrease the apparent reflectance
- R0=Surface reflectance function
AOT retrieval is not possible either when aerosol system reaches radiative equilibrium or when Phase function approximately matches surface reflectance function(which occur over bright surfaces)
