Integrated Dynamics‐Physics Coupling for Weather to Climate Models: GFDL SHiELD With In‐Line Microphysics

Abstract

Atmospheric models consist of two main parts: dynamical core and physical parameterizations. Traditionally, dynamical cores and physical parameterizations have been engineered in isolation for the sake of tractability (Donahue and Caldwell (2018); Gross et al. (2018), and references therein). These two independent components are coupled and advanced using the same time step, either parallel or sequentially split (Ubbiali et al., 2021). Ubbiali et al. (2021) analyzed six strategies of dynamics-physics coupling in atmospheric models. They emphasized that the coupling remained an open problem in atmospheric modeling and were conscious that significantly more effort is required to fully understand the implications for a full-fledged model. Gross et al. ( 2018) described many challenging aspects of dynamics-physics, including the time-stepping of different components, an incomplete understanding of the role of coupling, thermodynamic incompatibility between components, the extension to ocean and land coupling to the atmosphere, and more.Dynamics-physics coupling is complicated, mainly by the three following aspects.Standpoint 1: Dynamical and physical processes have different physical time scales, and the design of the dynamical core and dynamics-physics coupling should reflect this. Fast processes should be computed on a shorter time step and called more frequently, while slow processes should be computed on a longer time step and