Role of aircraft soot emissions in contrail formation
Article first published online: 7 JAN 2009
Copyright 2009 by the American Geophysical Union.
Geophysical Research Letters
Volume 36, Issue 1, January 2009
How to Cite
2009), Role of aircraft soot emissions in contrail formation, Geophys. Res. Lett., 36, L01804, doi:10.1029/2008GL036649., and (
- Issue published online: 7 JAN 2009
- Article first published online: 7 JAN 2009
- Manuscript Accepted: 2 DEC 2008
- Manuscript Received: 13 NOV 2008
 The susceptibility of microphysical properties of young contrails to changes in aircraft soot emissions is studied with a microphysical plume model. Liquid plume and ambient particles compete with exhaust soot particles for the formation of contrail ice particles, assuming that soot particles are activated into water droplets prior to homogeneous freezing. Soot controls ice formation in contrails for high number emission indices including the range of current global fleet values. A fivefold reduction of soot emissions from average levels of 5 × 1014 − 1015 (kg-fuel)−1 approximately halves the initial contrail visible optical depth. Further soot reduction reverses this trend at temperatures well below the formation threshold temperature unless emissions of sulfur and organics are cut substantially. Whether and to which degree reductions in soot emissions help mitigate the contrail climate impact depends on subsequent aircraft wake vortex processing of contrails and their development into contrail cirrus.