Parametric studies of contrail ice particle formation in jet regime using microphysical parcel modeling
- ISSN: 1680-7324
- DOI: 10.5194/acp-10-3261-2010
Condensation trails (contrails) formed from water vapor emissions behind\naircraft engines are the most uncertain components of the aviation\nimpacts on climate change. To gain improved knowledge of contrail and\ncontrail-induced cirrus cloud formation, understanding of contrail ice\nparticle formation immediately after aircraft engines is needed. Despite\nmany efforts spent in modeling the microphysics of ice crystal formation\nin jet regime (with a plume age <5 s), systematic understanding of\nparametric effects of variables affecting contrail ice particle\nformation is still limited. In this work, we apply a microphysical\nparcel modeling approach to study contrail ice particle formation in\nnear-field aircraft plumes up to 1000m downstream of an aircraft engine\nin the soot-rich regime (soot number emission index > 1 x 10(15)\n(kg-fuel)(-1)) at cruise. The effects of dilution history, ion-mediated\nnucleation, ambient relative humidity, fuel sulfur contents, and initial\nsoot emissions were investigated. Our simulation results suggest that\nice particles are mainly formed by water condensation on emitted soot\nparticles. The growth of ice coated soot particles is driven by water\nvapor emissions in the first 1000m and by ambient relative humidity\nafterwards. The presence of chemi-ions does not significantly contribute\nto the formation of ice particles in the soot-rich regime, and the\neffect of fuel sulfur contents is small over the range typical of\nstandard jet fuels. The initial properties of soot emissions play the\nmost critical role, and our calculations suggest that higher number\nconcentration and smaller size of contrail particle nuclei may be able\nto effectively suppress the formation of contrail ice particles. Further\nmodeling and experimental studies are needed to verify if our findings\ncan provide a possible approach for contrail mitigation.