 |
| Titel |
The evolution of microphysical and optical properties of an A380 contrail in the vortex phase |
| VerfasserIn |
J.-F. Gayet, V. Shcherbakov, C. Voigt, U. Schumann, D. Schäuble, P. Jessberger, A. Petzold, A. Minikin, H. Schlager, O. Dubovik, T. Lapyonok |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 14 ; Nr. 12, no. 14 (2012-07-26), S.6629-6643 |
| Datensatznummer |
250011348
|
| Publikation (Nr.) |
 copernicus.org/acp-12-6629-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| A contrail from a large-body A380 aircraft at cruise in the
humid upper troposphere has been probed with in-situ instruments onboard the
DLR research aircraft Falcon. The contrail was sampled during 700 s
measurement time at contrail ages of about 1–4 min. The contrail was in the
vortex regime during which the primary wake vortices were sinking 270 m
below the A380 flight level while the secondary wake remained above.
Contrail properties were sampled separately in the primary wake at 90 and
115 s contrail age and nearly continously in the secondary wake at contrail
ages from 70 s to 220 s. The scattering phase functions of the contrail
particles were measured with a polar nephelometer. The asymmetry parameter
derived from these data is used to distinguish between quasi-spherical and
aspherical ice particles. In the primary wake, quasi-spherical ice particles
were found with concentrations up to 160 cm−3, mean effective diameter
Deff of 3.7 μm, maximum extinction of 7.0 km−1, and ice water
content (IWC) of 3 mg m−3 at slightly ice-subsaturated conditions. The
secondary and primary wakes were separated by an almost particle-free wake
vortex gap. The secondary wake contained clearly aspherical contrail ice
particles with mean Deff of 4.8 μm, mean (maximum) concentration,
extinction, and IWC of 80 (350) cm−3, 1.6 (5.0)
km−1, and 2.5 (10) mg m−3,
respectively, at conditions apparently above ice-saturation. The
asymmetry parameter in the secondary wake decreased with contrail age from
0.87 to 0.80 on average indicating a preferential aspherical ice crystal
growth. A retrieval of ice particle habit and size with an inversion code
shows that the number fraction of aspherical ice crystals increased from 2%
initially to 56% at 4 min contrail age. The observed crystal size
and habit differences in the primary and secondary wakes of an up to
4 min old contrail are of interest for understanding ice crystal growth in
contrails and their climate impact. Aspherical contrail ice particles cause
less radiative forcing than spherical ones. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|