Evaluation of Implicit‐Explicit Additive Runge‐Kutta Integrators for the HOMME‐NH Dynamical Core. (11th December 2019)

• Record Type: Journal Article
• Authors: Vogl, Christopher J.; Steyer, Andrew; Reynolds, Daniel R.; Ullrich, Paul A.; Woodward, Carol S.
• Is Part Of: Journal of advances in modeling earth systems. Volume 11:Number 12(2019)
• Page Start: 4228
• Page End: 4244
• Publication Date: 2019-12-11
• Subjects: IMEX -- additive Runge‐Kutta -- nonhydrostatic -- dynamical core -- HOMME‐NH -- E3SM; Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1029/2019MS001700
• Languages: English
• ISSNs: 1942-2466

Abstract

Abstract: The nonhydrostatic High‐Order Method Modeling Environment (HOMME‐NH) atmospheric dynamical core supports acoustic waves that propagate significantly faster than the advective wind speed, thus greatly limiting the time step size that can be used with standard explicit time integration methods. Resolving acoustic waves is unnecessary for accurate climate and weather prediction. This numerical stiffness is addressed herein by considering implicit‐explicit additive Runge‐Kutta (ARK IMEX) methods that can treat the acoustic waves in a stable manner without requiring implicit treatment of nonstiff modes. Various ARK IMEX methods are evaluated for their efficiency in producing accurate solutions, ability to take large time step sizes, and sensitivity to grid cell length ratio. Both the gravity wave test and baroclinic instability test from the 2012 Dynamical Core Model Intercomparison Project are used to recommend 5 of the 27 ARK IMEX methods tested for use in HOMME‐NH. Plain Language Summary: The Energy Exascale Earth System Model (E3SM) is an ongoing effort to produce actionable projections of variability and change in the Earth system. Advances in computational power have allowed endeavors like E3SM to simulate physical phenomena at finer resolution than ever before. Modeling the atmosphere at these finer resolutions requires improving both the underlying mathematical models and computational techniques. This works focuses on the latter by evaluating cutting‐edge computational techniques on a recently developed atmosphere model and suggesting which of those techniques should be included in the next generation of E3SM. Key Points: When using certain ARK IMEX methods, the hydrostatic time step size can be used for the nonhydrostatic model No single ARK IMEX method outperforms the rest in all metrics, but a small subset does excel in most metrics Hyperviscosity and vertical remap errors can affect global energy error with increased spatial resolution