Supporting Model Design Decisions and Innovations via Model Hierarchies

This paper discusses how the use of model hierarchies and idealized test cases can inform the design of complex weather and climate models and thereby contribute to the improved representation of their physical processes. In particular, we focus on the (1) design decisions in the fluid dynamics component (the so-called dynamical core) and (2) the physics-dynamics coupling aspects of various community models, such as NOAA’s Unified Forecast System (UFS) and NCAR’s Community Earth System Model (CESM). The examples demonstrate that community infrastructure, like NCAR’s ‘Simpler Models’ framework, drives scientific innovations, enables lively community and student engagements, serves as a correctness tool, and supports the model design decisions. Additional innovations are needed to fully embrace the model hierarchy ideas in the UFS which will be briefly reviewed.