A year ago, NOAA and DOE signed an agreement calling for closer cooperation between NOAA and Oak Ridge National Laboratory. The agreement tasked ORNL with “providing research collaboration and technical support for high performance computing and data systems that will deliver improved climate data and model experiments.” Jim Rogers, director of operations for the National Center for Computational Sciences at ORNL, discusses the agreement and the goals for the Climate Modeling and Research System (CMRS), the initial supercomputer chosen for the collaborative work.

HPCwire: What are the scientific goals for CMRS? What kind of modeling resolution are you targeting? Will this allow you to add more components to the ensemble models?

Rogers: The high-level goal for this project is to develop better models for predicting climate variability and change. ORNL’s role is to provide NOAA with both the HPC resources and the collaborative support needed to extend and improve these models.

On NOAA’s current systems, the typical resolution of the coupled climate model has been limited to a grid increment of 200 km for the atmosphere, and 100 km for the ocean model because of limitations in computational resources. However, on the new Cray XE6, we expect that NOAA scientists will quickly transition to a much higher resolution 50 km atmosphere and 25 km ocean model. And while I expect that this will be the initial workhorse, NOAA is already working on a 25 km atmosphere and 10 km ocean model with better physics.

There are several things in play as we move to these higher resolution models. The first is identifying core-count sweet spots for the existing model, the second is improving the scalability of the current code so that it can effectively use larger numbers of cores, and the third is introducing a new version of the atmosphere that includes a more complete treatment of the upper-level atmospheric physics and dynamics.

HPCwire: Who are NOAA’s research partners in this endeavor?

Rogers: This agreement specifically includes collaboration among scientists within NOAA and DOE/ORNL. Jim Hack, Director of the National Center for Computational Sciences, is working with Brian Gross and Venkatramani Balaji of NOAA/GFDL to identify and scope these collaborative efforts.

HPCwire: Why did NOAA decide to use ORNL as a host site for CMRS?

Rogers: ORNL plays a leadership role for climate change science and is a well-established HPC resource provider, with the current fastest computer system in the world. NOAA has been using a significant number of processor hours at ORNL on both the Cray XT4 and XT5 since 2008. This existing relationship provides a strong basis for the more dedicated support that they will receive with the CMRS. This arrangement allows NOAA to leverage our unique strengths as the host site for the equipment, as well as collaborate on the science side in partnering two strong climate science communities.

HPCwire: As part of its energy research mission, ORNL has been active in climate research for a long time, but the lab has really stepped up its climate work in recent years, including recruiting top research talent in this field. What’s driving this escalation?

Rogers: ORNL has definitely increased its focus on climate modeling and research. Day to day, I see growth in this area through the Oak Ridge Climate Change Science Institute. There is a lot of momentum in this area, a lot of attention from the public, and significant opportunities for fostering collaborative work in earth systems modeling.

HPCwire: Is there a “critical mass” effect from having all this climate research talent and multiple petascale supercomputers in one place?

Rogers: There is clearly an advantage to this situation.

HPCwire: Do you expect the petascale CMRS system to attract even more climate research talent to the NOAA site at ORNL?

Rogers: The priorities for use of the CMRS system will be up to NOAA management, but it’s easy to imagine how the huge increase in capability will provide NOAA with the flexibility to do new things and more fully engage other components of the NOAA climate change program. The opportunity to work on state-of-the-art hardware will always be a draw, especially on this Cray XE6, which provides some very attractive features that even big brother “Jaguar” cannot provide, including denser, faster nodes and the higher-speed interconnect.

HPCwire: NOAA is providing ORNL with $215 million over five years for supporting the climate research work. This is federal stimulus money. How much do you expect this big funding infusion to accelerate progress in climate research?

Rogers: Only the first $73 million is ARRA [American Recovery and Reinvestment Act] money. That money has been budgeted for the acquisition, installation, operation, and support of the CMRS. Other funding sources up to the $215 million will round out many of the collaborative science projects and activities. The impact of this stimulus funding is pretty clear, though. In Year 1, the new CMRS provides a 5x increase in computational capability over NOAA’s current largest system. In the second year, the capacity quadruples to more than 1.1 petaflops. This is a huge resource, delivered in step with the scientific community’s needs.

HPCwire: How will the increased computational power and research funding affect America’s standing in the global climate research community? Will the US be taking on a bigger share of the work for IPCC [Intergovernmental Panel on Climate Change] or other collaborative projects?

Rogers: I certainly expect the CMRS systems to be used for IPCC AR5 [Fifth Assessment Report] work.

HPCwire: Is NOAA’s climate research work always collaborative, or do you sometimes compete with other large climate centers around the world?

Rogers: Climate science is by definition a highly collaborative enterprise. I imagine that this machine acquisition will put NOAA in a role to take on additional leadership roles in exploring questions about climate change.

HPCwire: This will bring the number of Cray petascale systems at ORNL to three. Why did you choose the Cray supercomputers for this work?

Rogers: This was the outcome of a competitive procurement that assessed a large number of factors, including technical solution and strategy, benchmarks, past performance, and total cost of ownership. Intense interest from the HPC vendors led to very good proposals. In the end, the Cray solution using the XE6 was the most competitive, demonstrating a very good fit for the high-resolution climate models, an aggressive installation and upgrade plan, and the greatest ability to deliver cycles to the NOAA climate community.

HPCwire: You’ll soon have the CMRS petascale system. What could you do with an exascale supercomputer?

Rogers: The climate modeling community has articulated plans to pursue higher-resolution models with much more realistic physics, with a goal of improving simulation fidelity. Exascale capabilities will be needed to achieve many of these challenging scientific goals. Of course, the modeling activities will need to be able to exploit a much more complex architecture to take advantage of an exascale computer, which will provide an equally challenging technical task for the climate community.