Journal Article

PreJuSER-17013

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Thin and subvisible cirrus and contrails in a subsaturated environment

Kübbeler, M. ; Hildebrandt, M. ; Meyer, J.FZJ* ; Schiller, C.FZJ* ; Hamburger, T. ; Jurkat, T. ; Minikin, A. ; Petzold, A. ; Rautenhaus, M. ; Schlager, H. ; Schumann, U. ; Voigt, C. ; Spichtinger, J.-F. ; Gayet, C. ; Gourbeyre, C. ; Krämer, M.

2011
EGU Katlenburg-Lindau

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Please use a persistent id in citations: http://hdl.handle.net/2128/9965  doi:10.5194/acp-11-5853-2011

Abstract: The frequency of occurrence of cirrus clouds and contrails, their life time, ice crystal size spectra and thus their radiative properties depend strongly on the ambient distribution of the relative humidity with respect to ice (RHice). Ice clouds do not form below a certain supersaturation and both cirrus and contrails need at least saturation conditions to persist over a longer period. Under subsaturated conditions, cirrus and contrails should dissipate. During the mid-latitude aircraft experiment CONCERT 2008 (CONtrail and Cirrus ExpeRimenT), RHice and ice crystals were measured in cirrus and contrails. Here, we present results from 2.3/1.7 h of observation in cirrus/contrails during 6 flights. Thin and subvisible cirrus with contrails embedded therein have been detected frequently in a subsaturated environment. Nevertheless, ice crystals up to radii of 50 mu m and larger, but with low number densities were often observed inside the contrails as well as in the cirrus. Analysis of the meteorological situation indicates that the crystals in the contrails were entrained from the thin/subvisible cirrus clouds, which emerged in frontal systems with low updrafts. From model simulations of cirrus evaporation times it follows that such thin/subvisible cirrus can exist for time periods of a couple of hours and longer in a subsaturated environment and thus may represent a considerable part of the cirrus coverage.

Keyword(s): J

Note: We greatly acknowledge Andreas Dornbrack for excellent analysis of the meteorological situation during CONCERT, Klaus Gierens for fruitful discussions about contrail formation and development and Dominik Schauble for great assistance with the campaign. Thanks are given to Eric Jensen who provides computer code to calculate contrail thermodynamics. Further, we thank the Falcon team operating the aircraft for their support and the DLR flight department for providing the meteorological parameters, as well as the Deutsche Flugsicherung (DFS) and the Deutsche Lufthansa for excellent help during the campaign. The CONCERT campaign was organized by the Junior research group AEROTROP and in part financed by the DLR project CATS (Climate optimized air traffic system).

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Contributing Institute(s):

1. Stratosphäre (IEK-7)

Research Program(s):

1. Atmosphäre und Klima (P23)

Appears in the scientific report 2011

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