This campaign will assess the capabilities of the different polarimeters for retrieval of aerosol and cloud microphysical and optical parameters, as well as their capabilities to derive aerosol layer height (near-UV polarimetry, O2 A-band). This work provides insight into the information content of future active and passive aerosol and clouds sensors being considered by the ACE pre-formulation study, and it is also relevant to other missions such as METOP-SG, EarthCare, and PACE. ACEPOL will also focus on the development and evaluation of aerosol retrieval algorithms that combine data from both active (lidar) and passive (polarimeter) instruments, and will also acquire data to help evaluate both current (i.e. CALIOP, CATS) and future spacebased lidar instruments. ACEPOL is a collaborative effort among the NASA ACE and CALIPSO projects as well as SRON Netherlands Institute for Space Research.