Spectral polarization of clear and hazy coastal skies.

Linear polarization of the clear daytime sky has often been measured as a spectrally integrated or quasi-monochromatic variable, but seldom as a spectral one. So we use a hyperspectral imaging system to measure skylight polarization at high spectral and angular resolutions for clear and hazy skies at our coastal site. The resulting polarization maps and spectra exhibit both commonalities and differences that seem unexplained by an existing polarized radiative transfer model. Comparing the measured polarization spectra with those predicted by aerosol single scattering suggests some basic verisimilitude tests for improving such models.