A New Approach for Coupled Regional Climate Modeling Using More than 10,000 Cores
This paper describes an alternative method for coupling atmosphere-ocean regional climate models that communicates momentum, radiation, heat and moisture fluxes between the atmosphere and ocean every time-step, while scaling to more than 10,000 cores. The approach is based on the reversibly staggered grid, which possesses excellent dispersive properties for modeling the geophysical fluid dynamics of both the atmosphere and the ocean. Since a common reversibly staggered grid can be used for both atmosphere and ocean models, we can eliminate the coupling overhead associated with message passing and improve simulation timings. We have constructed a prototype of a reversibly staggered, atmosphere-ocean coupled regional climate model based on the Conformal Cubic Atmospheric Model, which employs a global variable resolution cube-based grid to model the regional climate without lateral boundary conditions. With some optimization, the single precision, semi-implicit, semi-Lagrangian prototype model achieved 5 simulation years per day at a global 13 km resolution using 13,824 cores. This result is competitive with state-of-the-art Global Climate Models than can use more than 100,000 cores for comparable timings, making CCAM well suited for regional modeling.
Keywordsgeophysical fluid dynamics MPI regional climate modeling
- 2.McGregor, J.L.: C-CAM: Geometric aspects and dynamical formulation. CSIRO Marine and Atmospheric Research Technical Report 70 (2005), http://www.cmar.csiro.au/e-print/open/mcgregor_2005a.pdf
- 3.Schmidt, F.: Variable fine mesh in spectral global models. Beitr. Phys. Atmos. 50, 211–217 (1977)Google Scholar
- 4.Fox-Rabinovitz, M., Cote, J., Dugas, B., Deque, M., McGregor, J.L.: Variable resolution general circulation models: Stretchedgrid model intercomparison project (SGMIP). J. Geophys. Res. 111, D16104 (2006)Google Scholar
- 5.McGregor, J.L., Dix, M.: An updated description of the conformal-cubic atmospheric model. In: Hamilton, K., Ohfuchi, W. (eds.) High Resolution Simulation of the Atmosphere and Ocean, pp. 51–76. Springer (2008)Google Scholar
- 7.Worley, P., Craig, A., Dennis, J.: Performance ofthe community earth system model. In: 2011 International Conference High Performance Computing, Networking, Storage and Analysis (SC), Seattle, WA, pp. 1–11 (2011)Google Scholar