The Flying Laboratory FLab: development and application of a UAS to measure aerosol particles and trace gases in the lower troposphere

Uncrewed aircraft systems (UASs) are gradually being established in environmental research to study boundary layer conditions and phenomena in situ; however, due to payload limitations, UASs can typically measure only a limited number of atmospheric variables simultaneously. Here we present the Flying Laboratory (FLab), a hexacopter equipped with six instruments to measure aerosol particles (particle number concentration and size distribution; PM₁, PM₂.₅, and black carbon mass concentration), trace gases (CO₂, O₃), and meteorological variables (temperature, relative humidity, pressure, wind) in the lower troposphere in real time and with high temporal resolution. The instrumentation has been selected to provide an overview of relevant variables in urban and semi-urban environments and especially in the vicinity of aerosol sources. This paper describes the development of the technical setup of the Flying Laboratory, the characterization of the measurements with respect to horizontal and vertical motion of the UAS, and the optimization of measurement flight patterns. During two field experiments, FLab was applied to bridge the gap between ground-based and aircraft-based profiling measurements and to perform hourly vertical profiling flights up to 300 m above a ground-based reference station for 8 h. These applications demonstrate the capability of FLab to capture the evolution of the lower convective boundary layer during the day and the vertical particle transport in the afternoon up to 200 m above ground.

The drone-based Flying Laboratory FLab was developed to simultaneously measure aerosol (number concentration, size distribution, and black carbon), trace gas (O₃, CO₂), and meteorological variables. FLab was characterized in the field regarding limitations and biases due to different flight maneuvers. Two application cases are presented: analysis of the development of the lowermost troposphere (up to 300 m) and successfully bridging ground-based and aircraft- and radiosonde-based measurements.