Abstract
Current climate models have a limited ability to increase spatial resolution because numerical stability requires the time step to decrease. We describe a semi-Lagrangian method for tracer transport that is stable for arbitrary Courant numbers, and we test a parallel implementation discretized on the cubed sphere. The method includes a fixer that conserves mass and constrains tracers to a physical range of values. The method shows third-order convergence and maintains nonlinear tracer correlations to second order. It shows optimal accuracy at Courant numbers of 10-20, more than an order of magnitude higher than explicit methods. We present parallel performance in terms of strong scaling, weak scaling, and spatial scaling (where the time step stays constant while the resolution increases). For a 0.2° test with 100 tracers, the implementation scales efficiently to 10,000 MPI tasks.
| Original language | English |
|---|---|
| Pages (from-to) | 6778-6799 |
| Number of pages | 22 |
| Journal | Journal of Computational Physics |
| Volume | 230 |
| Issue number | 17 |
| DOIs | |
| State | Published - Jul 20 2011 |
| Externally published | Yes |
Funding
We sincerely thank the anonymous reviewers for their helpful suggestions and corrections. Portions of this work were funded by the Office of Biological and Environmental Research in the US Department of Energy. This research used resources of NERSC at Lawrence Berkeley National Laboratory and of the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory, both of which are supported by the Office of Science of the US Department of Energy.
| Funders | Funder number |
|---|---|
| Office of Biological and Environmental Research in the US Department of Energy | |
| U.S. Department of Energy | |
| Office of Science | |
| Oak Ridge National Laboratory |
Keywords
- Cubed sphere
- High resolution
- High-performance computing
- Semi-Lagrangian
- Spherical geometry
- Tracer transport