Challenges in Detecting Clouds in Polar Regions Using a Drone with Onboard Low-Cost Particle Counter

Abstract

It is expected that uncrewed aerial vehicles (UAVs) will be used increasingly for operational atmospheric soundings to cover a broader area of the lower troposphere, including that in the polar regions and over the oceans. During the Japanese Antarctic Research Expedition of 2022/2023, 172 vertical profiles up to a maximum height of 1000 m a.s.l. were conducted from mid-December 2022 to mid-March 2023 using a commercially available inexpensive drone launched from the icebreaker RV Shirase. Over a quarter of the flights encountered clouds and snow, of which half produced icing on the body and blades of the drone. The onboard aerosol counter detected an increase in the particle number concentration in the cloud layers, which was synchronized with an increase in the attenuated backscatter coefficient of a shipboard lidar ceilometer. In the presence of icing, the concentration of particles >1.0μm exceeded 5000 particles L−1 as a median value, while the concentration was <1000 particles L−1 for cases without icing. Using an onboard aerosol counter and/or land-based ceilometer would be useful for detecting the icing environments.