Development of a UAV-borne cavity-enhanced albedometer for in-situ measurements of the vertical profiles of aerosol optical properties

Vertical profiles of aerosol light scattering (b_scat), absorption (b_abs), as well as the single scattering albedo (SSA, ω), play an important role in the effects of aerosols on climate, air quality, and local photochemistry. However, direct measurement of the vertical profiles of these optical parameters remains challenging. Although some aircraft observations have been carried out, there is still large uncertainty.

In this presentation, we will report the development of an unmanned-aerial-vehicle (UAV)-borne cavity-enhanced aerosol single scattering albedometer (CEA-albedometer) operating at λ = 532 nm for simultaneous in-situ measurements of the vertical distributions of b_ext, b_scat, b_abs, and ω. The achieved detection precisions in laboratory were 0.38, 0.21, and 0.43 Mm^-1 for b_ext, b_scat, and b_abs, respectively, for a 1 s data acquisition time.

The UAV used here was a petrol-powered hexacopter with a flight height of up to 1.5 km and a speed of up to 20 m/s. The maximum take-off weight of the UAV was ~ 150 kg, and about 30 kg of equipment can be carried. The full load flight endurance time was about 80 minutes depending on the temperature and wind. It was controlled by a GPS module with a precision of 0.1 m in the horizontal direction and 0.05 m in the vertical direction.

The concept of using UAVs for atmospheric research began in the 1990s. Nowadays, it has developed rapidly, and various instruments have demonstrated impressive performance. The UAV flight platform reported here demonstrated good performance and will become a valuable and powerful tool for atmospheric boundary layer research.