Characteristics of sub-10 nm particle emissions from in-use commercial aircraft observed at Narita International Airport

• Main Authors: N. Takegawa, Y. Murashima, A. Fushimi, K. Misawa, Y. Fujitani, K. Saitoh, H. Sakurai
• Format: Article
• Language: English
• Published: Copernicus Publications 2021-01-01
• Series: Atmospheric Chemistry and Physics
• Online Access: https://acp.copernicus.org/articles/21/1085/2021/acp-21-1085-2021.pdf

<p>The characterization of ultrafine particle emissions from jet aircraft equipped with turbofan engines, which are commonly used in civil aviation, is an important issue in the assessment of the impacts of aviation on climate and human health. We conducted field observations of aerosols and carbon dioxide (<span class="inline-formula">CO₂</span>) near a runway at Narita International Airport, Japan, in February 2018. We used an ultrafine condensation particle counter (UCPC) and a condensation particle counter (CPC) with unheated and 350 <span class="inline-formula">^∘C</span> heated operation modes to investigate the contributions of sub-10 <span class="inline-formula">nm</span> size ranges to the total and the non-volatile particle number concentrations. The performance of the 350 <span class="inline-formula">^∘C</span> heated mode was tested in the laboratory to verify the consistency with existing methods for non-volatile particle measurements. We also used a scanning mobility particle sizer with unheated and 350 <span class="inline-formula">^∘C</span> heated modes and an engine exhaust particle sizer for the measurements of particle number size distributions. Spiked increases in the particle number concentrations and <span class="inline-formula">CO₂</span> mixing ratios were observed to be associated with the directions of wind from the runway, which can be attributed to diluted aircraft exhaust plumes. We estimated the particle number emission indices (EIs) for discrete take-off plumes using the UCPC, CPC, and <span class="inline-formula">CO₂</span> data. The median values of the total and the non-volatile particle number EIs for diameters larger than 2.5 <span class="inline-formula">nm</span> as derived from the UCPC data were found to be <span class="inline-formula">1.1×10¹⁷</span> and <span class="inline-formula">5.7×10¹⁵</span> kg per fuel, respectively. More than half the particle number EIs were in the size range smaller than 10 <span class="inline-formula">nm</span> for both the total and the non-volatile particles in most of the cases analyzed in this study. The significance of sub-10 <span class="inline-formula">nm</span> size ranges for the total particles in the diluted plumes was qualitatively consistent with previous studies, but that for the non-volatile particles was unexpected. Possible factors affecting the similarities and differences compared with the previous findings are discussed.</p>