Study On Polarized Characteristics Of Scattering Skylight At Different Atmospheric Conditions

Biologists'research shows that the desert ant can navigate with the patterns of the skylight polarization, because its vision nervous system is sensitive with angle of scattering skylight polarization. In these years, the polarized characteristics of scattering skylight and its applications to bionic navigation system have been the hot subjects in China. However, many factors influence the polarized characteristics of scattering skylight, and the atmospheric condition is the very important influencing factors.Therefore, the measurement and analysis on the polarized characteristics and distribution pattern of scattering skylight at different atmospheric conditions are pre-requisite for exploiting bionic navigation system.At first, we analyse the effect of atmosphere aerosol on scattering skylight through the atmospheric scattering theory. After that, the forming mechanisms and measuring principle for the polarized characteristics of scattering skylight are presented. Based on the measuring principle, we introduce the measuring model for the polarized characteristics of scattering skylight. Then, the skylight polarization measurement system is introduced simply.Using the measurement system, the measurements on the polarized characteristics of scattering skylight are performed in clear days, cloudy days or overcast days through the full-sky and solar vertical plane. Using the optimized data analysis software, the polarized characteristics of scattering skylight are acquired in the spectral range 450-475nm or 435-470nm, and the full-sky distribution patterns of scattering skylight at different atmospheric conditions are presented by two-dimensional graphics.Furthermore, the pilot study on meteorologic factors (humidity, polluting index and cloud) influence on the polarized characteristics of scattering skylight is given.The study indicate that the polarized characteristics of scattering skylight are in agreement with Rayleigh model in sunny skies (clear days, cloudy days or partly cloudy days), and the deviation of polarized characteristics of scattering skylight in overcast days from Rayleigh model is pretty large.