Investigating the Small-Scale Vertical and Horizontal Variability of the Atmospheric Boundary Layer Aerosol using Unmanned Aerial Vehicles

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The aim of the proposed project is the in situ investigation of the vertical and horizontal distribution of aerosol particles in the polar atmospheric boundary layer (ABL). Small-scale atmospheric processes and the variability of aerosol particles are investigated using an in situ approach by unmanned aerial systems (UAS). They expand the capabilities for aerosol investigation and fill the gap between continuous ground-based observations and extensive aircraft measurements. This project will use three UAS simultaneously. A miniature aerosol measurement system, detecting the number concentration in eight particle size ranges, has been developed and characterized for the new UAS ALADINA in the framework of the DFG funded project LA 2907/5-1, BA 1988/14-1, WI 1449/22-1. Of special importance is the deployment of two condensation particle counters with different detection threshold, adjustable for diameters between 5 and 20 nm, for identification of very small, recently formed particles. The two other UAS of type MASC have been equipped for measurements of the turbulent thermodynamic properties of the ABL (e.g. turbulent fluxes) on horizontal flights and vertical profiles, and additionally for measuring larger particle number concentration. Different flight pattern of the three UAS simultaneously provide a 3D picture of atmospheric parameters and the aerosol distribution. The deployment of the measurement systems during the preceding projects allowed the characterization of aerosol variability and especially the vertical dynamics of new particle formation at a rural, continental site (Melpitz, Germany). It was shown that new particle formation starts typically at the top of the ABL, and particles are transported downwards by subsequent convective mixing, where they can be observed with ground-based sensors.The well-established systems will now be used to determine the aerosol variability in the polar ABL (Ny-Alesund, Svalbard), with the background of continuous ground-based in situ and remote sensing observations at ground level and at the Zeppelin observatory (470 m). Of special interest is the transition of aerosol properties from rather large, aged aerosol particles in spring (Arctic haze) to presumably small, locally formed particles in summer. The small-scale highly variable orography modifies the distribution of aerosol, and local effects like special wind systems (along the fjord) occur. The observed data of particle nucleation are further used for numerical studies to improve the understanding of the particle nucleation in polar regions.