Implementation of an Instrumented UAV for Cloud Seeding Operations

An unmanned aerial vehicle (UAV) has been instrumented with an air motion sensor, printed optical particle spectrometer (POPS) and a cloud droplet probe (CDP) for identifying regions that are optimum for cloud seeding operations. The on-board firmware takes the measurements from the sensors to determine cloud base temperature, CCN concentration (estimated from the POPS) and updraft velocity and uses these data to estimate the success probability of precipitation development from hygroscopic seeding material dispensed at cloud base. The precipitation probability is determined from cloud simulations using a parcel model to calculate droplet activation, growth and coalescence from a broad range of input cloud base temperatures, updraft velocities and CCN spectra. The cloud model has been validated with aircraft measurements in the United Arab Emirates where the UAV system will be used in the summer of 2020.