Understanding Shallow Cumulus Clouds as an Open System for Parameterization Improvement

English Abstract:

Although it has been increasingly recognized that shallow cumuli are open systems with interactions with environment, sub-cloud boundary layer turbulence and aerosols, our understanding of the interactions and resulting relationships between entrainment rate, turbulent mixing, cloud microphysics, environmental properties such as relative humidity, and sub-cloud aerosols are far from complete. This study will report our research on treating shallow cumuli as open systems by exploring the complex relationships and process couplings and seeking ways to improve their representation in climate models. In particular, we will present new parameterizations for entrainment rate, homogeneous mixing degree, and microphysics, and introduce a new dynamical mixing diagram for investigating such an open system. The relationship of shallow cumulus clouds to sub-cloud turbulence and aerosols will be also explored. We will concentrate on continental shallow cumuli occurring over the ARM SGP site and use a combined investigation of observational analysis, numerical modeling and theoretical formulation.