Anvil Cirrus and Stratiform Convective Outflow

Project S3 aims at an improved process understanding and characterization of the impact of convection on upper tropospheric cloudiness and its change in a warming climate, contributing to discussions on the decrease in upper tropospheric cloudiness and an increase in anvil top height with climate change (FAT hypothesis).

Organizational structure of the S3 project and its connection to the rest of the HD(CP)² project.

Microphysical and macrophysical cloud parameterizations will be improved, selected convective events explored, and the vertical structure and temporal evolution of the anvil and stratiform outflow and their dependence on the background temperature in observations and in ICON simulations will be examined. Another goal is to better understand and quantify the formation and lifecycle of anvils and mid-level stratiform clouds generated by deep convection. Their impact on the water budget in the upper troposphere is studied and their representation within models improved. Moreover, the macrophysical, microphysical and optical properties of convectively generated ice clouds and their dependence on background temperatures in observations and model will be studied.

Work package 1 -

Workpackage 1 focuses on the formation, evolution and growth of ice particles in deep convective clouds and the formation of convectively-generated cirrus (anvils) and convectively-generated mid-level stratiform clouds (stratiform region of convective systems).

Work package 2 -

Work package 2 investigates the occurrence as well as the microphysical and macrophysical properties of cirrus outflow of Warm Conveyor Belts (WCB). The use of a newly developed microphysics scheme allows us to easily differentiate between the contribution of multiple ice formation processes such as homogeneous and heterogeneous nucleation, freezing of cloud droplets and ice multiplication.

Work package 3&4 - 

Work packages 3 and 4 focus on the convective outflow and its representation in NWP (numerical weather prediction) and GCM (global circulation) models. The goal is to achieve a better understanding and ultimately better representation of processes which influence the development of convection and its outflow when parameterized.

Work package 5 - 

Work packages 5 and 3 study the impact of convection on the water budget and variability in the upper troposphere, anvil top temperatures, ice supersaturation and the macro-scale distribution (e.g. cover and ice water) of ice clouds and their temporal evolution in the ICON-GCM (global circulation model).

Work package 6 - 

To provide more process-oriented validation of convective systems in the model system, we apply a combination of on-line feature identification and a trajectory tool. In this approach, “massless” particles are started in regions identified to be favoured to convection initiation. These particles are transported in the model system in a Lagrangian framework, resulting in on-line trajectories.

Work package 7 - Using satellites to observe and validate the macro- and microphysics of convective ice clouds

Work package 8 - 

In workpackage 8 four goals are specified:

  • the statistical evaluation of anvil properties
  • the evaluation of the ice-microphysical scheme
  • a validation of the satellite retrieval products, and
  • the determination of the retrieval accuracy of the Ice Water Content (IWC) Cloudnet product.

Work package 9 - 


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