A New Cloud Macrophysics Scheme Based on Dual-Triangular PDFs

Cloud exerts substantial impacts on global climate. Thus, it is important to accurately simulate cloud properties in a general circulation model (GCM). However, many GCMs still have difficulty in simulating the observed cloud. In this study, we developed a new cloud macrophysics scheme that simulates both detrained cumulus and stratus in a single framework. Compared with previous schemes, our scheme computes both cloud fraction and cloud condensate for each liquid, ice, and mixed-phase clouds using a single triangular PDF, such that it does not suffer from the inconsistency issue between cloud fraction and cloud condensate. In addition, the new scheme constructs dual-triangular PDFs for individual detrained cumulus and stratus using a set of prognostic governing equations that describe complex interactions between cloud and various physical and dynamical processes. We implemented our new cloud macrophysics scheme into the Seoul National University Atmosphere Model Version 0 with a Unified Convection Scheme (SAM0-UNICON). In this talk, we will explain how we developed this dual-PDF-based cloud macrophysics scheme and its impacts on global climate in SAM0-UNICON.