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| Titel |
Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the properties of contrail ice particles in the jet regime |
| VerfasserIn |
H.-W. Wong, A. J. Beyersdorf, C. M. Heath, L. D. Ziemba, E. L. Winstead, K. L. Thornhill, K. M. Tacina, R. C. Ross, S. E. Albo, D. L. Bulzan, B. E. Anderson, R. C. Miake-Lye |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 19 ; Nr. 13, no. 19 (2013-10-11), S.10049-10060 |
| Datensatznummer |
250085746
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| Publikation (Nr.) |
 copernicus.org/acp-13-10049-2013.pdf |
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| Zusammenfassung |
| Contrails and contrail-induced cirrus clouds are identified as the most
uncertain components in determining aviation impacts on global climate
change. Parameters affecting contrail ice particle formation immediately
after the engine exit plane (< 5 s in plume age) may be critical to ice
particle properties used in large-scale models predicting contrail radiative
forcing. Despite this, detailed understanding of these parametric effects is
still limited. In this paper, we present results from recent laboratory and
modeling studies conducted to investigate the effects of water and soot
emissions and ambient conditions on near-field formation of contrail ice
particles and ice particle properties. The Particle Aerosol Laboratory (PAL)
at the NASA Glenn Research Center and the Aerodyne microphysical parcel
model for contrail ice particle formation were employed. Our studies show
that exhaust water concentration has a significant impact on contrail ice
particle formation and properties. When soot particles were introduced, ice
particle formation was observed only when exhaust water concentration was
above a critical level. When no soot or sulfuric acid was introduced, no ice
particle formation was observed, suggesting that ice particle formation from
homogeneous nucleation followed by homogeneous freezing of liquid
water was unfavorable. Soot particles were found to compete for
water vapor condensation, and higher soot concentrations emitted into the
chamber resulted in smaller ice particles being formed. Chamber conditions
corresponding to higher cruising altitudes were found to favor ice particle
formation. The microphysical model captures trends of particle extinction
measurements well, but discrepancies between the model and the optical
particle counter measurements exist as the model predicts narrower ice
particle size distributions and ice particle sizes nearly a factor of two
larger than measured. These discrepancies are likely due to particle loss
and scatter during the experimental sampling process and the lack of
treatment of turbulent mixing in the model. Our combined experimental and
modeling work demonstrates that formation of contrail ice particles can be
reproduced in the NASA PAL facility, and the parametric understanding of
the ice particle properties from the model and experiments can potentially
be used in large-scale models to provide better estimates of the impact of
aviation contrails on climate change. |
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