A New Approach to Estimate Vertical Profile of Aerosol Absorption Coefficient and Single-Scattering Albedo in the Lower Troposphere

This poster presents a new method to retrieve a vertical profile of aerosol absorption and aerosol single-scattering properties based on the synergy of different measurement techniques. The presented methodology used in-situ observation of black carbon (BC) concentration by the micro-aethalometer AE-51 mounted on-board small unmanned aerial systems (sUAS) or tethered balloon as well as the remote sensing measurements made by sun photometer and lidar. From micro-aethalometer profiling of BC concentration, the aerosol absorption coefficient is estimated after taking into account correction for multiple light-scattering between aerosol and quartz filter. Profiles of the aerosol absorption coefficient at 880 nm have been compared with absorbing aerosol optical depth retrieved from CIMEL sun photometer and MISR observation during biomass burning events in 2015 over Central Europe. For the single-scattering albedo retrieval, the aerosol lidar or ceilometer data are used to obtain the extinction profiles. Due to the overlap problem, the single scattering albedo can be obtained from a few hundred meters above ground level up to the range of sUAS or tethered balloon measurements which usually are between 1 and 2 km. The uncertainty of retrieved single-scattering albedo changes between ±0.01 and ±0.04. The accuracy of this method depends on the aerosol extinction coefficient estimation (Raman on elastic channel method) but also for which wavelength is calculated (532 or 870 nm). In addition, this method is more suitable for polluted conditions. For very clean conditions, the aerosol absorption, as well as aerosol single scattering albedo, are retrieved with relatively high noise level due to a very low value of the black carbon concentration.

This work was funded by National Science Center within the project: Integrated studies of climate processes involving absorbing aerosols, grant nr. 2012/05/E/ST10/01578.