Development and use of a lightweight sampling system for height-selective UAV-based measurements of organic aerosol particles

Abstract. Organic aerosols (OAs) are introduced into the atmosphere from a variety of natural and anthropogenic sources. Especially in the submicrometer range, the organic fraction contributes to a large proportion of the particle mass and thus has an impact on climate and air quality. To gain insights into sources and sinks and the significance of dispersion, mixing, and aging processes for OA, vertical profiling of the concentration of organic aerosols is particularly helpful. Therefore, the aim of this study is to present an aerosol particle sampler that is suitable to be used on board uncrewed aerial vehicles (UAVs). The sampler consists of a three-dimensionally printed filter holder connected to a lightweight high-performance pump that can generate a flow rate of up to 103 slpm for up to 30 min. The sampler was characterized and applied on a proof-of-concept study during the BISTUM23 campaign in August 2023 in Southern Germany. Vertical profiles were measured with three samplers mounted on ground and UAVs and collected aerosol particles at an altitude of 1.5, 120, and 500 m above ground level simultaneously. The filters were analyzed with UHPLC-HRMS, and a targeted approach was used to determine vertical profiles and diurnal trends of biogenic, anthropogenic, and biomass burning marker compounds. A non-targeted analysis revealed a high number of CHO-containing compounds, which were oxidized to a greater extent during the course of the day and at increasing altitudes. The system presented here provides a comparatively simple and cost-effective way to sample OA at different altitudes and at different locations and thus obtain vertical concentration profiles of the organic aerosol composition.