Introduction of a prognostic cloud ice scheme in the ECHAM general circulation model: Impact on climate and climate sensitivity

Abstract

A new cloud microphysics scheme including a prognostic treatment of cloud ice (PCI) is developed to yield a more physically based representation of the components of the atmospheric moisture budget in the general circulation model ECHAM. The new approach considers cloud water and cloud ice as separate prognostic variables. A precipitation formation which can distinguish between maritime and continental clouds by considering the cloud droplet number concentration in addition to the cloud water content is introduced. Based on different observational data sets, the cloud droplet number concentration is proportional to the sulfate aerosol mass concentration as given from the simulated sulfer cycle with ECHAM. Results obtained from the new scheme are compared to satellite observations and in-situ measurements of cloud physical and radiative properties. (orig./KW)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman