Abstract. Atmospheric aerosol particles are important for our planet’s climate because they interact with radiation and clouds. Hence, having characterised methods to collect aerosol from aircraft for detailed offline analysis are valuable. However, collecting aerosol, particularly coarse mode aerosol, onto substrates from a fast moving aircraft is challenging and can result in both losses and enhancement in aerosol. Here we present the characterisation of an inlet system designed for collection of aerosol onto filters on board the UK’s BAe 146 Facility for Airborne Atmospheric Measurements (FAAM) research aircraft. We also present an offline Scanning Electron Microscopy (SEM) technique for quantifying both the size distribution and size resolved composition of the collected aerosol. We use this SEM technique in parallel with online underwing optical probes in order to experimentally characterise the efficiency of the inlet system. We find that the coarse mode aerosol is sub-isokinetically enhanced, with a peak enhancement at around 10 μm up to a factor of three under typical operating conditions. Calculations show that the efficiency of collection then decreases rapidly at larger sizes. In order to minimise the isokinetic enhancement of coarse mode aerosol we recommend sampling with total flow rates above 50 L min−1; operating the inlet with the bypass fully open helps achieve this by increasing the flow rate through the inlet nozzle. With the inlet characterised, we also present single particle chemical information obtained from X-ray spectroscopy analysis which allows us to group the particles into composition categories. Our intention is to use the composition information in parallel with filter based ice nucleating particle measurements in order to correlate composition and ice nucleating particle concentrations.
Fine Particle Measurements Inside and Outside Tunnel-Ventilated Broiler Houses