Abstract:

The DOE's Energy Exascale Earth System Model (E3SM) simulates the earth system on the world's largest supercomputers. Simulation of the atmosphere takes a substantial portion of the computation. The atmosphere component has three parts: dynamics, physics parameterizations, and transport of trace species. The second two dominate the computational cost. A tracer field is required to preserve several properties, including conserve mass, preserve shape, and maintain tracer consistency. To maximize computational efficiency, it is common to apply different spatial and temporal discretizations to the tracer transport equations than to the dynamical equations, and to use different grids for dynamics and physics. Using different discretizations and grids increases the challenge of preserving properties. I will describe, first, the mathematical structure of these interrelated problems and our approach to solving them; second, the efficient semi-Lagrangian tracer transport algorithm our approach enables. Finally, I will present computational performance results.