Field observations of aerosol particles in aircraft takeoff and taxiing plumes: A case study at Kobe Airport, Japan

Abstract Aerosol particles emitted from aircraft were measured in the vicinity of Kobe Airport (UKB), an offshore airport in Japan, in the spring (May) and fall (October–November) of 2021. The observation site was located at a distance of ∼290 and ∼110 m from the centerline of the runway and the taxiway, respectively. There were no significant non-aviation emission sources of aerosol particles around the site. This location enabled the unique identification of aircraft exhaust plumes transported from the runway and taxiway from specific aircraft under real-world operating conditions. Total and nonvolatile particle number concentrations in aircraft exhaust plumes were measured using condensation particle counters (CPCs) coupled with an evaporation tube heated at 350 °C. Most of the aircraft identified at UKB were Boeing 737–800 and Embraer 170–200 series equipped with CFM56-7B and CF34-8 engine variants, respectively. The particle number emission indices (EIs) attributed to the CFM56-7B engines were compared with those reported by previous studies (the total and nonvolatile particles for takeoff) and those archived in the International Civil Aviation Organization (ICAO) Aircraft Engine Emissions Databank (the nonvolatile particles for takeoff and idle). The median total and nonvolatile particle number EIs for takeoff showed good agreement (within a factor of 2) with those from the previous studies and ICAO Databank, whereas the nonvolatile particle number EIs for taxiing were much higher (more than an order of magnitude) than those estimated from the ICAO Databank. Possible factors affecting the similarity and difference in the particle number EIs are discussed.