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Noctilucent clouds (NLCs) occur during summer in the polar region ataltitudes around 83 km. They consist of ice particles witha typical size around 50 nm. The shape of NLC particles isless well known but is important both for interpreting opticalmeasurements and modeling ice cloud characteristics. In this paper,NLC modeling of microphysics and optics is adapted to usecylindrical instead of sphericalparticle shape. The optical properties of the resulting ice clouds arecompared directly to NLC three-color measurements by the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) Rayleigh/Mie/Raman (RMR) lidarbetween 1998 and 2014. Shape distributions including both needle- anddisc-shaped particles are consistent with lidar measurements. The bestagreement occurs if disc shapes are 60 % more common thanneedles, with a mean axis ratio of 2.8. Cylindrical particles causestronger ice clouds on average than spherical shapes with anincrease of backscatter at 532 nm by ≈ 30 % and about 20 % in ice mass density.This difference is less pronounced for bright than forweak ice clouds. Cylindrical shapes also cause NLCs to have larger buta smaller number of ice particles than for spherical shapes

Impact of particle shape on the morphology of noctilucent clouds