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. Warm clouds, consisting of liquid clouddroplets, play an important role in modulating the amount of incoming solarradiation to Earth's surface and thus the climate. The size and numberconcentration of these cloud droplets control the reflectance of the cloud,the formation of precipitation and ultimately the lifetime of the cloud.Therefore, in situ observations of the number and diameter of cloud dropletsare frequently performed with cloud and aerosol spectrometers, whichdetermine the optical diameters of cloud particles (in the range of up to afew tens of micrometers) by measuring their forward-scattering cross sections invisible light and comparing these values with Mie theoretical computations.The use of such instruments must rely on a fast working scheme consisting ofa limited pre-defined uneven grid of cross section values that correspondsto a theoretically derived uneven set of size intervals (bins). However, asmore detailed structural analyses of warm clouds are needed to improvefuture climate projects, we present a new numerical post-flight methodologyusing recorded particle-by-particle sample files. The Mie formalism producesa complicated relationship between a particle's diameter and its forward-scattering cross section. This relationship cannot be expressed in ananalytically closed form, and it should be numerically computed point bypoint, over a certain grid of diameter values. The optimal resolutionrequired for constructing the diagram of this relationship is thereforeanalyzed. Cloud particle statistics are further assessed using a fine gridof particle diameters in order to capture the finest details of the cloudparticle size distributions. The possibility and the usefulness of usingcoarser size grids, with either uneven or equal intervals, is also discussed.For coarse equidistant size grids, the general expressions of cloudmicrophysical parameters are calculated and the ensuing relative errors arediscussed in detail. The proposed methodology is further applied to a subsetof measured data, and it is shown that the overall uncertainties in computingvarious cloud parameters are mainly driven by the measurement errors of theforward-scattering cross section for each particle. Finally, the influenceof the relatively large imprecision in the real and imaginary parts of therefractive index of cloud droplets on the size distributions and on theensuing cloud parameters is analyzed. It is concluded that, in the presenceof high atmospheric loads of hydrophilic and light-absorbing aerosols, suchimprecisions may drastically affect the reliability of the cloud dataobtained with cloud and aerosol spectrometers. Some complementarymeasurements for improving the quality of the cloud droplet sizedistributions obtained in post-flight analyses are suggested.

Post-flight analysis of detailed size distributions of warm cloud droplets, as determined in situ by cloud and aerosol spectrometers