Computational aspects of a scalable high-order discontinuous Galerkin atmospheric dynamical core

A new atmospheric general circulation model (dynamical core) based on the discontinuous Galerkin (DG) method is developed. This model is conservative, high-order accurate and has been integrated into the NCAR's high-order method modeling environment (HOMME) to leverage scalable parallel computing capability to thousands of processors. The computational domain for this 3-D hydrostatic model is a cubed-sphere with curvilinear coordinates; the governing equations are cast in flux-form. The horizontal DG discretization employs a high-order nodal basis set of orthogonal Lagrange-Legendre polynomials and fluxes of inter-element boundaries are approximated with Lax-Friedrichs numerical flux. The vertical discretization follows the 1-D vertical Lagrangian coordinates approach combined with the cell-integrated semi-Lagrangian conservative remapping procedure. Time integration follows the third-order strong stability preserving explicit Runge-Kutta scheme. The domain decomposition is applied through space-filling curve approach. To validate the 3-D DG model in HOMME framework, a baroclinic instability test is used and the results are compared with those from the established models. Parallel performance is evaluated on IBM Blue Gene/L supercomputers.