Abstract：Study on polarized skylight spectral characters while observation geometry changing in different solar zenith angles (SZA), viewing zenith angles (VZA) or relative azimuth angles (RAA). Simulation calculation of cloudless daylight polarimetric spectrum is realized basedon the solver, vector discrete ordinate method, of radiative transfer equation.In the Sun’s principal and perpendicular plane, the spectral irradiance data, varying at wavelengths in the range between 0.4 and 3 μm, are calculated toextend the atmospheric polarization spectral information under the conditions: the MODTRAN solar reference spectrum is the only illuminant source; the main influencing factors of polarized radiative transfer include underlying surface albedo, aerosol layers and components, and the absorption of trace gases. Simulationanalysis results: (1) While the relative azimuth angle is zero, the magnitude of spectrum U/I is lower than 10-7 and V/I is negligible, the degree of polarization and the spectrum Q/I are shaped like the letter V or mirror-writing U. (2) In twilight, when the Sun is not in FOV of the detector, the polarizationof the daytime sky has two maximum near 0.51 and 2.75 μm, and a minimum near1.5 μm. For arbitrary observation geometry, the spectral signal of V/I may beignored. According to observation geometry, choosing different spectral bands or polarized signal will be propitious to targets detection.
Key words：Atmospheric optics;Polarimetric spectrum;Radiative transfer equation;Stokes vector;Observation geometry
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