Snow Particle Characterization. Part A: Statistics of Microphysical Properties of Snow Crystal Populations from Recent Observations Performed during the ICE GENESIS Project

Measurements in snow conditions performed in the past were rarely initiated and best suited for pure and extremely detailed quantification of microphysical properties of a series of microphysical parameters, needed for accretion modelling. Within the European ICE GENESIS project, a considerable effort of natural snow measurements has been made during winter 2020/21. Instrumental means, both in-situ and remote sensing were deployed on the ATR-42 aircraft, as well as on the ground (ground station at ‘Les Eplatures’ airport in the Swiss Jura Mountains with ATR-42 overflights). Snow clouds and precipitation in the atmospheric column were sampled with the aircraft, whereas ground based and airborne radar systems allowed extending the observations of snow properties beyond the flight level chosen for the in situ measurements. Overall, five flight missions have been performed at different numerous flight levels (related temperature range from -10°C to +2°C) beyond the ‘Les Eplatures’ airport. The manuscript focuses primarily on statistical retrievals of temperature dependent microphysical snow properties, with in particular, the total condensed water content (TWC), number and mass size distributions, the latter allowing to calculate the mass representative diameter proxy of the median mass diameter (MMD), ice crystal effective density, and a series of snow particle size dependent descriptors of morphological properties (3D volumetric diameter versus 2D image diameter, sphericity, crosswise sphericity, aspect ratio). In addition, snow properties from the ground based MASC imaging probe and complementary retrievals of snow properties from ground based and airborne radar observations are included in this study.