The idea behind CR-SIM is to create an accurate radar forward model operator consistent with several microphysics schemes that converts the model variables into the form of radar observations and thus to enable the direct comparison between numerical weather model output and radar observations. The CR-SIM can be applied in order to reproduce characteristic (polarimetric) signatures commonly found in (polarimetric) radar and lidar observations and examine the performance of different microphysical schemes and the assumptions related to scattering characteristics of observed cloud and precipitation systems.