Preprints
https://doi.org/10.5194/egusphere-2023-1264
https://doi.org/10.5194/egusphere-2023-1264
13 Jun 2023
 | 13 Jun 2023

Jet aircraft lubrication oil droplets as contrail ice-forming particles

Joel Ponsonby, Leon King, Benjamin Murray, and Marc Stettler

Abstract. The radiative characteristics and lifetime of contrails are dependent on the number concentration of ice-forming particles in the engine exhaust plume. Aircraft gas turbine engines produce a variety of particles, yet it is understood that non-volatile black carbon aggregates are the dominant source of ice-forming particles with typical, fossil-derived jet fuel. However, with cleaner combustion technologies and the adoption of alternative fuels (e.g., hydrogen or synthetic aviation fuel), non-volatile black carbon particle emissions are expected to decrease or even be eliminated. Under these conditions, contrail properties will depend upon the concentration and characteristics of particles other than black carbon. Ultrafine (<100 nm) jet lubrication oil droplets constitute a significant fraction of the total organic particulate matter released by aircraft, however their ability to form contrail ice crystals is hitherto unexplored. In this work, we experimentally investigate the activation and freezing behaviour of lubrication oil droplets using an expansion chamber, assessing their potential as ice-forming particles. We generate lubrication oil droplets with a geometric mean mobility diameter of (100.9 ± 0.6) nm and show that these activate to form water droplets despite their hydrophobicity. These subsequently freeze when the temperature is below ~235 K. We find that nucleation on lubrication oil droplets should be considered in future computational studies - particularly under soot-poor conditions - and that these studies would benefit from particle size distribution measurements at cruise altitude. Overall, taking steps to reduce lubrication oil number emissions would help reduce the climate impact of contrail cirrus.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint

16 Feb 2024
Jet aircraft lubrication oil droplets as contrail ice-forming particles
Joel Ponsonby, Leon King, Benjamin J. Murray, and Marc E. J. Stettler
Atmos. Chem. Phys., 24, 2045–2058, https://doi.org/10.5194/acp-24-2045-2024,https://doi.org/10.5194/acp-24-2045-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

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Aerosol emissions from aircraft engines contribute to the formation of contrails, which have a...
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