A Cheyenne retrospective: Looking back on seven extraordinary years

Scientists now understand the Earth system far better than they did in 2017—thanks, in no small part, to Cheyenne, a unique supercomputer.

In its seven years of operations, the flagship supercomputer at the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR) served thousands of scientists internationally.

"Cheyenne was an extraordinary success," said Thomas Hauser, director of the NSF NCAR Computational and Information Systems Lab (CISL). "Its leading-edge computing and data handling capabilities enabled scientists to gain new insights into the Earth system… [yielding] significant benefits for society."

Operations launched in January 2017 at the NSF NCAR Wyoming Supercomputing Center (NWSC). A 5.34-petaflops system, Cheyenne could perform 5.34 quadrillion calculations per second, tripling its predecessor’s power. At launch, it ranked as the 20th fastest supercomputer.

The system was originally slated to be replaced after five years. But when the COVID-19 pandemic struck, severely disrupting supply chains, Cheyenne was called upon to serve an additional two years—maintained and supported by a dedicated staff of about 20 NWSC engineers—until the necessary parts were available to build its successor. Last month, Cheyenne was finally replaced by Derecho, a 19.87-petaflops system tripling Cheyenne’s performance. 

Since 2017, Cheyenne delivered over 7 billion core hours, served over 4,400 users, and supported nearly 1,300 NSF awards. It played a key role in education, supporting more than 80 university courses and training events. Nearly 1,000 projects were awarded for early-career graduate students and postdocs. Perhaps most tellingly, Cheyenne-powered research generated over 4,500 peer-review publications, dissertations and theses, and other works.

Such numbers, however, tell only part of the story. What made Cheyenne especially valuable was how it illuminated Earth systems in ways that strengthen societal resilience.

Researchers used Cheyenne to run increasingly detailed models simulating complex processes and how they might unfold in the future. Scientists also harnessed its computing power to run multiple simulations, or ensembles, to quantify a given event’s probability—providing needed intelligence for policy and resource planning.

Examples of transformative research with Cheyenne include:

• Extremely high-resolution global simulations of the atmosphere. Researchers highlighted an underappreciated type of rapid intensification of hurricanes to help forecasters better anticipate such weather events.
• Insight into the impacts of wildfire emissions on air quality and climate. One study shows that smoke from massive Australian bushfires in 2019-20 helped generate a rare multi-year La Niña event. A separate study shows that increasingly large and intense wildfires in the Pacific Northwest have altered the seasonal pattern of air pollution across North America.
• New modeling approaches with large datasets. The Decadal Prediction Large Ensemble (DPLE), with a staggering 24,800 simulated years of climate information, helps identify the event types most predictable as far as a decade in advance. 

“Cheyenne was a special machine that has certainly earned its retirement,” said NSF NCAR Director Everette Joseph. 

To learn more about Cheyenne's service to the Earth system science community and view more examples of the science that Cheyenne enabled, see the full news story from the University Corporation for Atmospheric Research (UCAR).