The ESA-STSE study ICAROHS exploits the potential improvements and benefits of novel multi-wavelength High Spectral Resolution Lidar (HSRL) technology combined with innovative retrieval methods for future satellite missions. Single-wavelength HSRL data from several field studies form the data base for developing improved scientific algorithms for retrievals of aerosol optical properties and of tools for future multi-wavelength spaceborne HSRL instrument assessments. These quality-controlled observational data feed into the existing EarthCARE simulator (ECSIM), which serves as the platform for algorithm development and verification. Light scattering by non-spherical particles is implemented into ECSIM as scattering libraries based on T-matrix calculations. Recommendations for future multi-wavelength HSRL missions are formulated on the basis of a combined retrieval of aerosol properties from the entire available lidar and in-situ data. This retrieval study forms the benchmark for aerosol properties accessible by respective HSRL missions and defines the technical limits for required accuracy and resolution of the lidar input data to the novel algorithms.