Single scattering of partly oriented aspherical cloud ice crystals at sub-millimeter wavelengths

The recently suggested sub-millimeter sensors for the global observation of cirrus clouds all bear several channels widely separated from each other and spanning the range from 180 to 880 GHz. While the potential for retrieving the integrated ice water content and the mean effective particle size of ice clouds has been investigated, the quantitative retrieval of particle shape and orientation information is still an active research area. Here we investigate the influence of the parameters of a Gaussian distribution of the horizontal particle orientation on the single scattering cross section. It is only slightly affected, but the polarization signal is reduced to 90% of the completely horizontally oriented case if the standard deviation σ_β of the horizontal distribution is 15° and reduced to 50% if σ_β = 30°.