The temporal evolution of a long‐lived contrail cirrus cluster: Simulations with a global climate model. Issue 7 (14th April 2016)

• Record Type: Journal Article
• Authors: Bock, Lisa; Burkhardt, Ulrike
• Is Part Of: Journal of geophysical research. Volume 121:Issue 7(2016)
• Page Start: 3548
• Page End: 3565
• Publication Date: 2016-04-14
• Subjects: contrail cirrus -- contrails in climate model -- microphysical development of contrails; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2015JD024475
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: The representation of contrail cirrus in climate models has advanced in the last years tremendously. Nevertheless, uncertainties in particular regarding the representation of contrail microphysics still remain. Properties of young contrail cirrus differ from those of natural cirrus due to the large ice crystal number concentration common in contrails. Consequently, microphysical process rates in contrail cirrus, which control its lifetime, can be very different to those in natural cirrus. We extend a contrail cirrus scheme within a climate model by implementing a microphysical two‐moment scheme and study the life cycle of a contrail cirrus cluster. In an idealized experiment we study the properties and microphysical process rates of a contrail cirrus cluster in a large and long‐lived ice supersaturated region. We find that at flight level contrail cirrus display their typical high ice crystal number concentration (of about 10–100 cm −3 ) for a few hours with far lower densities in lower levels caused by sedimentation. After about 7 h contrail cirrus have spread considerably so that even at flight level associated ice crystal number concentrations have dropped to values that prohibit fast relaxation of ice supersaturation. The reduced ice crystal number and the resulting limited water uptake in the contrail cirrus limit the lifetime of the contrail cirrus cluster to about 10 h even though surrounding conditions would be still favorable for contrail cirrus persistence. In our case studies, contrail cirrus resembles natural cirrus regarding their ice crystal number concentration and size after 5–7 h. Key Points: Contrail cirrus with two‐moment microphysics as independent cloud class in a climate model Microphysical processes control the lifetime of contrail cirrus in long‐lived ice supersaturated areas In aged contrail cirrus deposition is limited due to low ice crystal number concentration