Unmanned-aerial-vehicle-borne cavity enhanced albedometer: a powerful tool for simultaneous in-situ measurement of aerosol light scattering and absorption vertical profiles.

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. High-precision in-situ measurements of the vertical profiles of these properties are challenging and therefore uncommon. We report here the development of a portable cavity-enhanced albedometer operating at λ = 532 nm for use aboard an unmanned aerial vehicle (UAV). Multi-optical parameters, b _scat , b _abs , extinction coefficient b _ext , and ω, can be measured simultaneously in the same sample volume. 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 albedometer was installed on an hexacopter UAV and simultaneous in-situ measurements of the vertical distributions of b _ext , b _scat , b _abs , and ω were realized for the first time. Here we report a representative vertical profile up to a maximum height of 702 m with a vertical resolution of better than 2 m. The UAV platform and the albedometer demonstrate good performance and will be a valuable and powerful tool for atmospheric boundary layer research.