Premium
The temporal evolution of a long‐lived contrail cirrus cluster: Simulations with a global climate model
Author(s) -
Bock Lisa,
Burkhardt Ulrike
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd024475
Subject(s) - cirrus , ice crystals , atmospheric sciences , environmental science , supersaturation , meteorology , physics , thermodynamics
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.