Measurement and modeling of light scattering by small particles.

At the University of Hertfordshire we measure and model light scattering by small particles, in particular by such relevant for climate research. The measurements comprise phase functions, linear polarization of single levitated particles (ice analogues, Saharan dust) and 2D scattering patterns for interpretation of airborne instrument data (SID, PPD1). In order to extend the applicability of geometric optics towards lower size parameters, we have developed the ray tracing with diffraction on facets (RTDF) model. It combines ray tracing with diffraction on flat facets, and is suitable for rapid computation of scattering on faceted dielectric objects such as ice crystals. or by facetted approximations of more complex shapes. Due to its low computational cost it allows the calculation of 2D scattering patterns, which are useful for interpretation of nephelometric data.