Judith Curry (PI)
Georgia Institute of Technology
curryja@eas.gatech.edu

Parameterization of Cloud Particle Activation and Growth

Within the context of the Cloud Modeling and Analysis Initiative (CMAI), this proposal is targeted specifically at the development and evaluation of parameterizations for cloud microphysical processes related to cloud formation.  This includes parameterization of the following elements:  droplet activation, ice nucleation (homogeneous, heterogeneous deliquescence freezing and various modes of heterogeneous drop freezing), kinetic effects on droplet and ice crystal diffusional growth, ice crystal habit and its impact on diffusional growth and fall speed, and subgridscale supersaturation variations.  Correct parameterization of these processes is essential for accurate simulation of cloud feedback processes, particularly in the presence of a variable aerosol environment.    We will augment our previous theoretical and detailed process modeling research on cloud microphysical processes to extend the parameterized elements into a comprehensive dual moment bulk microphysics scheme capable of treating all cloud types as needed by global models.  An additional parameterization challenge is to treat these processes appropriately in a model with coarse spatial resolution and relatively long time steps.  In evaluating the parameterizations, a hierarchy of models is used in this study, including parcel model, single column model, cloud resolving model, and mesoscale model, including explicit bin resolving microphysics and aerosol transport.  In the first year of the project, existing case studies from GCSS, CRYSTAL-FACE, FIRE.ACE and DOE ARM will be used to evaluate the parameterizations.  Once data from CloudSat and CALIPSO are available, the A-Train suite of satellites will be used along with DOE ARM data for initialization and evaluation of the models. The exact case study information, including forcing data, will be provided to the GCSS DIME web site.  Model sensitivity studies will be conducted to assess whether the parameterization complexity is necessary and sufficient.

+ Back to Participant Listing