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1Tetra Tech, Inc., 630 N. Rosemead Boulevard, Pasadena, California 91107, USA.
Applied Optics
|August 1, 1983
Summary
Simple radiometers can measure scattered sunlight moments to determine scattering medium properties. This method uses N+1 meters to deduce N moments of the volume scattering function, simplifying radiative transfer analysis.
Area of Science:
- Atmospheric optics
- Radiative transfer theory
Background:
- Simple radiometers measure integral moments of scattered sunlight radiance.
- These instruments lack azimuth (phi) and zenith (theta) angle scanning capabilities.
Purpose of the Study:
- To propose a method for deducing properties of scattering media using simple radiometers.
- To determine N moments of the volume scattering function from integral radiance measurements.
Main Methods:
- Utilizing N+1 specially designed meters to measure integral moments Lambda(l) through Lambda(N+1).
- Designing each meter with an angular response approximating a polynomial of degree N in cos theta.
- Applying Boltzmann's equation of radiative transfer in spherical harmonics form.
Main Results:
- The proposed meter design allows for simple processing of Lambda(j) measurements.
- N moments of the volume scattering function can be deduced from the measurements.
- The theory simplifies significantly when using the spherical harmonics form of Boltzmann's equation.
Conclusions:
- Judicious design of simple radiometers enables the determination of key scattering medium properties.
- This approach offers a computationally efficient method for analyzing scattered sunlight data.
- The theoretical framework is robust and simplifies complex radiative transfer problems.
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