title: Measurements of skylight polarization: a case study in urban region with high-loading aerosol.
abstract: We investigate skylight polarization patterns in an urban region using our developed full-Stokes imaging polarimeter. A detailed description of our imaging polarimeter and its calibration are given, then, we measure skylight polarization patterns at wavelength λ=488  nm and at solar elevation between -05°10' and +35°42' in the city of Hefei, China. We show that in an urban region with high-loading aerosols: (1) the measured degree of linear polarization reaches the maximum near sunset, and large areas of unpolarized sky exist in the forward sunlight direction close to the Sun; (2) the position of neural points shifts from the local meridian plane and, if compared with a clear sky, alters the symmetrical characteristics of celestial polarization pattern; and (3) the observed circular polarization component is negligible.
authors.forename: Lianghai
authors.initials: L
authors.lastname: Wu
authors.forename: Jun
authors.initials: J
authors.lastname: Gao
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Fan
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang