J. M. Dennis, R. Jacob, M. Vertenstein, T. Craig, and R. Loy, "Toward an Ultra-High Resolution Community Climate System Model for the BlueGene Platform," Journal of Physics: Conference Series, vol. 78, 2007, pp. 012030. Also Preprint ANL/MCS-P1446-0707, July 2007. [pdf]
Global climate models need to simulate several small, regional-scale processes which affect the global circulation in order to accurately simulate the climate. This is particularly important in the ocean where small scale features such as oceanic eddies are currently represented with ad-hoc parameterizations. There is also a need for higher resolution to provide climate predictions at small, regional scales. New H=high-performance computing platforms such as the IBM BlueGene can provide the necessary computational power to perform ultra-high resolution climate model integrations. We have begun to investigate the scaling of the individual components of the Community Climate System Model to prepare it for integrations on BlueGene and similar platforms. Our investigations show that it is possible to successfully utilize O(32K) processors. We describe the scalability of five models: the Parallel Ocean Program (POP), the Community Ice CodE (CICE), the Community Land Model (CLM), and the new CCSM sequential coupler (CPL7) which are components of the next generation Community Climate System Model (CCSM); as well as the High-Order Method Modeling Environment (HOMME) which is a dynamical core currently being evaluated within the Community Atmospheric Model. For our studies we concentrate on 1/10o resolution for CICE, POP, and CLM models and 1/4o resolution for HOMME. The ability to simulate high resolutions on the massively parallel petascale systems that will dominate high-performance computing for the foreseeable future is essential to the advancement of climate science.