text: At the
IRC business meeting on the 30 June 2011 in Melbourne it was decided to start a new working group IPRT (International working group on Polarized Radiative Transfer). Polarized radiative transfer becomes increasingly important because polarization measurements can be used to retrieve in particular cloud and aerosol optical and micro-physical properties with unprecedented accuracy. There are now several instruments which are able to measure polarization and the analysis of these measurements requires accurate radiative transfer codes. The working group shall work on intercomparison studies and it should define benchmarks for polarized radiative transfer calculations. Furthermore input data (optical properties of ice clouds and aerosols as well as surface reflection matrices) shall be made available for the scientific community.