Microphysical investigation of the seeder and feeder region of an Alpine mixed-phase cloud

Abstract. The seeder–feeder mechanism has been observed to enhance orographic precipitation in previous studies. However, the microphysical processes active seeder and feeder region are still being understood. In this paper, we investigate of a mixed-phase cloud passing over Swiss Alps, focusing on (1) fallstreaks enhanced radar reflectivity originating from top generating cells (seeder region) (2) persistent low-level produced by boundary layer circulation (feeder region). Observations were obtained multi-dimensional set instruments including ground-based remote sensing instrumentation (Ka-band polarimetric radar, microwave radiometer, wind profiler), situ tethered balloon system, aerosol measurements. observations suggest that ice formation growth within cells, which is consistent with observational uncertainties exist regarding dominant these cells. Here propose different mechanisms potentially nucleation (convective overshooting, radiative cooling, droplet shattering) attempt estimate their potential contribution an nucleating particle perspective. Once exceeded threshold value, became fully glaciated. Local flow effects lee side mountain barrier induced small-scale topographic feature inner-Alpine valley. measurements production secondary particles likely due Hallett–Mossop process fragmentation upon ice–ice collisions. Therefore, may have partly responsible for elevated crystal number concentrations previously clouds at mountaintop observatories. Secondary can precipitation.