Unified Entrainment and Detrainment Closures for Extended Eddy-Diffusivity Mass-Flux Schemes.

Area of Science:

• Atmospheric Science
• Climate Modeling
• Turbulence Parameterization

Background:

• Accurate parameterization of subgrid-scale turbulence and convection is crucial for climate models.
• Existing schemes often struggle to represent diverse dynamical regimes consistently.

Purpose of the Study:

• To develop and validate a unified parameterization scheme for subgrid-scale turbulence and convection.
• To improve the representation of entrainment and detrainment processes in atmospheric models.

Main Methods:

• An extended eddy-diffusivity mass-flux (EDMF) scheme was developed with novel entrainment and detrainment closures.
• Closures model entrainment/detrainment as a combination of turbulent diffusion and dynamical processes.
• Off-line evaluation against large eddy simulations (LES) and subsequent single-column model (SCM) testing.

Main Results:

• The EDMF scheme with new closures successfully unifies parameterization across dry, shallow, and deep convection regimes.
• Good agreement was found between SCM and LES results for thermodynamic profiles, cloud liquid water, and turbulent statistics.
• The SCM accurately captures the diurnal cycle of convection and precipitation onset.

Conclusions:

• The extended EDMF scheme provides a unified and improved approach to parameterizing subgrid-scale processes in climate models.
• The new entrainment and detrainment closures enhance the model's ability to simulate various convective phenomena.
• This advancement contributes to more reliable climate projections and weather forecasting.