Atmos. Chem. Phys. Discuss., 9, 22337-22363, 2009
© Author(s) 2009. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Parametric studies of contrail ice particle formation in jet regime using one-dimensional microphysical modeling
H.-W. Wong and R. C. Miake-Lye
Center for Aero-Thermodynamics, Aerodyne Research, Inc., Billerica, Massachusetts, USA

Abstract. Condensation trails (contrails) formed from water vapor emissions behind aircraft engines are the most uncertain components of the aviation impacts on climate change. To gain improved knowledge of contrail and contrail-induced cirrus cloud formation, understanding of contrail ice particle formation immediately after aircraft engines is needed. Despite many efforts spent in modeling the microphysics of ice crystal formation in jet regime (with a plume age <5 s), systematic understanding of parametric effects of variables affecting contrail ice particle formation is still limited. In this work, we apply a one-dimensional modeling approach to study contrail ice particle formation in near-field aircraft plumes up to 1000 m downstream of an aircraft engine in the soot-rich regime (soot number emission index >1×1015 (kg-fuel)−1) at cruise. The effects of ion-mediated nucleation, ambient relative humidity, fuel sulfur content, and initial soot emissions were investigated. Our simulation results suggest that ice particles are mainly formed by water condensation on emitted soot particles. The growth of ice coated soot particles is driven by water vapor emissions in the first 1000 m and by ambient relative humidity afterwards. The presence of chemi-ions does not significantly contribute to the formation of ice particles, and the effect of fuel sulfur content is small over the range typical of standard jet fuels. The initial properties of soot emissions play the most critical role, and our calculations suggest that higher number concentration and smaller size of contrail particle nuclei may be able to effectively suppress the formation of contrail ice particles, providing a possible approach for contrail mitigation.

Citation: Wong, H.-W. and Miake-Lye, R. C.: Parametric studies of contrail ice particle formation in jet regime using one-dimensional microphysical modeling, Atmos. Chem. Phys. Discuss., 9, 22337-22363, doi:10.5194/acpd-9-22337-2009, 2009.
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