Description and Evaluation of a New Deep Convective Cloud Model Considering In‐Cloud Inhomogeneity

Abstract

Stabilizing the atmosphere and ventilating the sub-cloud layer through vertical transport of moisture, moist convection is an important sub-grid scale process that still needs to be parameterized in general circulation models (GCMs) in the coming decades (Plant & Yano, 2016). The purpose of convection parameterization is to provide feedback on sub-grid scale convection to the large-scale fields as tendency terms. It is important to keep in mind that for achieving this goal, we do not have to introduce full details of convection into a parameterization. Rather, it must constitute a caricature of the reality of convection, as emphasized by Yano (2014b). Therefore, early convection schemes only considered the feedback without describing the convective clouds (e.g., the moist adjustment scheme of Manabe et al. (1965) or the moisture convergence scheme of Kuo (1965)). However, some shortcomings, including fixed tropical temperature profiles (Arakawa, 2004) and unreasonable convective moistening profiles (Emanuel, 1994), are related to such an oversimplified approach, indicating that an idealized caricature cannot encompass the collective effect of a series of complex processes during the convection. A practical way to mitigate this problem is to describe more basic features of convective clouds in detail in convection schemes. As a result, convection schemes started to adopt a bulk or spectrum mass-flux (plume) formulation (e.g.,

Wave-Convection Interactions Amplify Convective Parameterization Biases in the South Pacific Convergence Zone

“…Indeed, adding the stochastic scheme developed by into the ZM scheme, which allows the generation of larger cloud base mass fluxes, has also been shown to improve the simulated SPCZ during austral summer (Wang et al, 2016). The cloud base mass flux in a single-column model using the NEW scheme is nearly twice that in the ZM scheme (Chu & Lin, 2023), lending further weight to this idea.…”

“…simulations using the ZM convective parameterization and may be associated with the double-ITCZ bias (Wang et al, 2016;Chu & Lin, 2023). Replacing the ZM scheme with the new convective parameterization proposed by Chu and Lin (2023) eliminates much of the low bias in precipitation along the climatological axis of the SPCZ (Figure 1b,f).…”

“…simulations using the ZM convective parameterization and may be associated with the double-ITCZ bias (Wang et al, 2016;Chu & Lin, 2023). Replacing the ZM scheme with the new convective parameterization proposed by Chu and Lin (2023) eliminates much of the low bias in precipitation along the climatological axis of the SPCZ (Figure 1b,f). Differences in SPCZ intensity between the ORIG and NEW simulations strongly indicate that parameterized convection plays a critical role in simulating the SPCZ, as simply replacing the convection scheme increases rainfall in the SPCZ region by nearly 50% (Figure 1h).…”

Generalized eddy‐diffusivity mass‐flux formulation for the parametrization of atmospheric convection and turbulence

“…have been developed (e.g., Bechtold et al, 2001;Bretherton et al, 2004;Chu & Lin, 2023;Hohenegger & Bretherton, 2011;Kim & Kang, 2012), in which a and b are coefficients that requires closure.…”

Generalized eddy-diffusivity mass-flux (GEM) formulation for the parameterization of atmospheric convection and turbulence

“…have been developed (e.g. Bechtold et al, 2001;Bretherton et al, 2004;Hohenegger and Bretherton, 2011;Kim and Kang, 2012;Chu and Lin, 2023), in which a and b are coefficients that requires closure.…”