G8 Multilateral Research Funding - ICOMEX

There is an ongoing need for a capability to run atmospheric models at higher resolution, to improve weather forecasts, particularly of severe weather, to improve understanding of climate processes, and to improve climate prediction. Higher resolution can only be achieved by exploiting future supercomputing platforms based on hundreds of thousand of processors; for such architectures communication between processors is a significant bottleneck to performance, and requires quite different algorithms from those used historically.

Grids based on a refined icosahedron provide a promising basis for a new generation of atmospheric models. Their quasi-uniform resolution should minimize the communication bottleneck giving good performance. Recent advances in numerical analysis mean that schemes of sufficient accuracy are now available. Local refinement of the grid is possible where higher resolution is needed for specific applications. An icosahedral grid model has been used operationally by the German Weather Service for several years, and several other groups have such models at an advanced stage of development.

The proposed project will assess and compare the parallel computing performance of a number of icosahedral grid models and carry out research to improve their performance. The specific research topics include the development of an abstract model description scheme to separate (as far as possible) numerical analysis issues from computer science issues, a model implementation targeted on Graphical Processing Unit (GPU) based architectures, development and evaluation of elliptic solvers to determine the feasibility of stable long-time-step integration schemes, the development of an internal postprocessing package to provide diagnostics required by the user while minimizing the data output bottleneck, and development of strategies to optimize input/output. The University of Exeter will contribute particularly to the elliptic solver and postprocessing work packages.

The immediate beneficiaries of this research are the participating modelling groups; the research will enable them to simulate the atmosphere more efficiently and at unprecedented resolution on massively parallel computers for both research and operational prediction.

Several of the participating models are supported for use by a wider research community; those researchers, and the users of their research, will also benefit.

The rapid evolution of supercomputers towards massively parallel architectures means there is a pressing need for algorithms to evolve to be able to exploit future computer power. The results of this project will be of interest to a wide scientific computing community, both in atmospheric modelling and in other fields. Specifically, the PI is participating in a new UK collaborative project (NGWCP) between NERC, STFC and the Met Office to develop a next generation atmospheric model dynamical core for use by the Met Office and the UK research community; NGWCP will benefit significantly from the links with ICOMEX.

The ultimate users of this research are the public, a wide range of businesses and services, local and national government, and other policy makers who make use of weather forecasts and climate predictions.