Sensitivity of radiative properties of persistent contrails to the ice water path 1Dalton Research Institute, Manchester Metropolitan University, Manchester, UK
05 Sep 2012
2Forschungszentrum, Jülich Institut für Energie und Klimaforschung Stratosphäre, Jülich, Germany
3Met Office, Exeter, UK
Received: 13 Apr 2011 – Published in Atmos. Chem. Phys. Discuss.: 13 Jul 2011 Abstract. The dependence of the radiative properties of persistent linear contrails on
the variability of their ice water path is assessed in a two-stream radiative
transfer model. It is assumed that the ice water content and the effective
size of ice crystals in aged contrails do not differ from those observed in
natural cirrus; the parameterization of these two variables, based on a
correlation with ambient temperature derived from in situ observations,
allows a more realistic representation than the common assumption of fixed
values for the contrail optical depth and ice crystal effective radius.
Revised: 26 Jul 2012 – Accepted: 13 Aug 2012 – Published: 05 Sep 2012
The results show that the large variability in ice water content that aged
contrails may share with natural cirrus, together with an assumed contrail
vertical thickness between 220 and 1000 m, translate into a wider range of
radiative forcings from linear contrails [1 to 66 m Wm−2] than that
reported in previous studies, including IPCC's [3 to 30 m Wm−2].
Further field and modelling studies of the temporal evolution of contrail
properties will thus be needed to reduce the uncertainties associated with
the values assumed in large scale contrail studies.
Citation: De León, R. R., Krämer, M., Lee, D. S., and Thelen, J. C.: Sensitivity of radiative properties of persistent contrails to the ice water path, Atmos. Chem. Phys., 12, 7893-7901, doi:10.5194/acp-12-7893-2012, 2012.