Spectral fine‐structure in the polarisation of skylight

Abstract

High‐spectral resolution polarisation measurements of the clear daylight sky reveal an unexpected rich spectral fine‐structure in the polarisation super‐imposed on the more familiar broad‐band continuum. This polarisation spectrum shows the spectral fingerprints of scattering and absorption processes which is illustrated with radiative transfer calculations. In particular, radiative transfer calculations suggest the potential of high‐spectral resolution polarimetry within absorption bands for remote sensing of aerosol vertical distribution, which is relevant to the Earth's radiation budget and ozone hole chemistry. In addition, the presence of spectral fine‐structure in the polarisation of skylight also has relevance to radiance measurements performed with polarisation sensitive spectrometers, such as the space‐based GOME instrument.