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| Titel |
A climatology of formation conditions for aerodynamic contrails |
| VerfasserIn |
K. Gierens, F. Dilger |
| 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. 21 ; Nr. 13, no. 21 (2013-11-07), S.10847-10857 |
| Datensatznummer |
250085798
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| Publikation (Nr.) |
 copernicus.org/acp-13-10847-2013.pdf |
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| Zusammenfassung |
Aircraft at cruise levels can cause two kinds of contrails, the well
known exhaust contrails and the less well-known aerodynamic
contrails. While the possible climate impact of exhaust contrails
has been studied for many years, research on aerodynamic contrails
began only a few years ago and nothing is known about a possible
contribution of these ice clouds to climate impact. In order to make
progress in this respect, we first need a climatology of their
formation conditions and this is given in the present paper.
Aerodynamic contrails are defined here as line shaped ice clouds
caused by aerodynamically triggered cooling over the wings of an
aircraft in cruise which become visible immediately at the trailing
edge of the wing or close to it. Effects at low altitudes like
condensation to liquid droplets and their potential heterogeneous
freezing are excluded from our definition. We study atmospheric
conditions that allow formation of aerodynamic contrails. These
conditions are stated and then applied to atmospheric data: first to
a special case where an aerodynamic contrail was actually observed
and then to a full year of global reanalysis data. We show where,
when (seasonal variation), and how frequently (probability)
aerodynamic contrails can form, and how this relates to actual
patterns of air traffic. We study the formation of persistent
aerodynamic contrails as well. Furthermore, we check whether aerodynamic
and exhaust contrails can coexist in the atmosphere. We show that
visible aerodynamic contrails are possible only in an altitude range
between roughly 540 and 250 hPa, and that the ambient temperature is
the most important parameter, not the relative humidity. Finally, we
argue that currently aerodynamic contrails
have a much smaller climate effect than exhaust contrails, which may
however change in future with more air traffic in the tropics. |
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