Abstract
Performance of the HOMME-NH nonhydrostatic atmosphere dynamic dynamic core is critical for the success of the science campaigns of E3SM v2 and beyond. In this poster we present results from the effort to develop efficient IMEX time-integration methods for the HOMME-NH nonhydrostatic dycore. The HOMME-NH dycore is numerically stiff since it supports vertically propagating acoustic waves whose resolution is irrelevant for climate science and will destabilize explicit integrators without a stringent step-size restriction. Implicit-explicit (IMEX) Runge-Kutta (RK) methods for time-integration of the primitive equations in HOMME-NH can increase the CFL stability limit beyond that of traditional explicit methods at a much lower computational cost per time-step than fully implicit methods. The IMEX-KG methods are a family of second and third order accurate IMEX RK methods designed specifically for efficient time-integration in HOMME-NH. Analysis of the joint stability region of the IMEX-KG methods enabled the development of methods whose CFL stability limit is determined by the hydrostatic CFL limit.