Modeling of effect of polarization in UV sky radiance during twilight
Abstract
Accurate description of radiation field in the atmosphere requires solution of the transfer equation in unknown vector of Stokes parameters, which characterize the radiance intensity and the radiance polarization. A simplified treatment of light as a scalar value equal to the radiance intensity may have only limited area of applications. A few studies compared previously results of the vector and the scalar radiative models and showed that scalar calculations are in error by up to 8-10% for many cases. Though several observational conditions were exploited, effect of polarization in modeling of UV radiance has not been yet investigated for twilight conditions. We have estimated error of scalar calculation relative to more accurate vector modeling for scattered spectral radiance observed from the ground during twilight. Simulation has been carried out for the solar deep angle up to 8 degree below the horizon for UV-A and UV-B wavelengths. Model atmospheres take into account molecular and aerosol scattering, gas and aerosol absorption, and Labertian surface albedo. Error of scalar calculation reaches 8% and significantly depends on wavelength. Influence of total ozone content, aerosol loading and albedo on polarized UV radiance is discussed.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.2235P