Modulation of the Bifurcation in Radiative-Convective Equilibrium by Gray-Zone Cloud and Turbulence Parameterizations

Abstract

If it is the author's pre-published version, changes introduced as a result of publishing processes such as copy-editing and formatting may not be reflected in this document. For a definitive version of this work, please refer to the published version.Thanks to the advances in computing power, modern numerical weather prediction (NWP) has achieved regional resolutions of  E 1 km (Lean et al., 2008;Raynaud & Bouttier, 2017;Seity et al., 2011). Global simulations at kilometer-scale resolutions are also actively achieved by the modeling community (Wedi et al., 2020). However, grid spacings of such sizes also inhibit further improvement of weather and climate models due to some phenomena, such as turbulence in the gray zone (also known as terra incognita). The gray zone refers to situations in which the model mesh cannot fully resolve turbulence and in which turbulence cannot be assumed to be mostly unresolved and in a quasi-equilibrium state (Chow et al., 2019;Wyngaard, 2004). Since such assumptions form the basis of traditional turbulence models in large-eddy simulations (LES) and NWP models, both LES-type and NWP-type turbulence models may underperform in the gray zone.