| 摘要 |
PURPOSE:To enhance the accuracy of an inspection value, by simultaneously measuring intensity of direct solar radiation and peripheral luminous intensity and adapting a phase function preliminarily calculated in the vicinity of a scattering angle of 20 deg. to correct the change in air turbidity. CONSTITUTION:At first, formulae II, III are introduced in place of the second item taulambda, m of formula I. Herein, Ealambda is the intensity of scattering light (solar peripheral light) at a scattering angle theta from the sun, DELTAOMEGA is the opening angle of a sun photometer, P(costheta) is phase function prescribing the angle distribution of scattering light and omega0 is the albedo (reflectivity) of a particle determined by the optical property of an aerosol. At first, if the phase function P(costheta) is calculated on the basis of the optical properties of various aerosols as a parameter, the value of the phase function becomes constant in the vicinity of a scattering angle of 20 deg. even if the optical property of each aerosol changes. Therefore, if the Ealambda scattering intensity of the formula III is measured in the vicinity of the scattering angle of 20 deg., tau* is determined. That is, if intensity of direct solar radiation Elambda as well as the scattering intensity E1lambda, phase func tion omega0 and reflectivity at the scattering angle of 20 deg. are given, inspection con stant CE0 can be determined with good accuracy.
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