PHIPS-HALO: the airborne particle habit imaging and polarscattering probe – Part 3: Single Particle Phase Discrimination andParticle Size Distribution based on Angular Scattering Function

Abstract. A major challenge for for in-situ observations in mixed phase clouds remains the phase discrimination and sizing of cloud hydrometeors. In this work, we present a new method to determine the phase of individual cloud hydrometeors based on their angular light scattering behaviour employed by the PHIPS airborne cloud probe. The phase discrimination algorithm is based on the difference of distinct features in the angular scattering function of spherical and aspherical particles. The algorithm is calibrated and validated using a large data set gathered during two in-situ aircraft campaigns in the Arctic and outhern Ocean. Comparison of the algorithm with manually classified particles showed that we can confidently discriminate between spherical and aspherical particles with a 98 % accuracy. Furthermore, we present a method to derive particle size distributions based on single particle angular scattering data for particles in a size range from 100 μm