Scientists hope to glimpse
the secret life of clouds

(page 3 of 3)

Models must account for these and other physical properties, including matter – that is, water.

Besides moisture and momentum, "thunderstorms carry other things (carbon dioxide and other chemical species) through great depths of the atmosphere very quickly."

Cumulus clouds, Randall says, make the upper troposphere wet by transporting water from its source, the oceans. "A lot of it will rain out along the way, but some of it is still left and it gets spread out up there and makes cirrus clouds, comprised largely of ice, which are very important for climate. We're especially interested to see how storms that create cirrus affect the climate."

The simulations at ORNL enlist 2 million processor hours on Jaguar and are supported by DOE's Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. The grant is a follow-up on a 2008 INCITE allocation of nearly 154,000 processor hours at NERSC, most of them on Franklin, a Cray XT4. NERSC.s director allocated an additional 2 million hours to Randall.s group to continue development while Jaguar was off-line for testing.

The GCRM also will give scientists new insights into tropical cyclones, "dangerous but very beautiful, very powerful storms that the GCRM will simulate quite well because of its extremely high resolution, " Randall says.

"Tropical cyclones are much bigger than thunderstorms, and in fact they contain many thunderstorms simultaneously. They affect the climate in part by cooling the sea surface as they move over the ocean."

Besides Arakawa, Konor and Jung, Randall's co-investigators are Colorado State's Ross Heikes and Pacific Northwest National Laboratory's Karen Schuchardt and Bruce Palmer. Randall also directs the Center for Multiscale Modeling of Atmospheric Processes, sponsored by the National Science Foundation.

The DOE work is part of the five-year Climate Change Prediction Program (CCPP) project, sponsored by DOE's Office of Biological and Environmental Research. CCPP and SciDAC comprise the two cores of DOE's Climate Modeling Program.

The simulations at ORNL enlist 2 million processor hours on Jaguar and are supported by DOE's Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. The grant is a follow-up on a 2008 INCITE allocation of nearly 154,000 processor hours at NERSC, most of them on Franklin, a Cray XT4. NERSC's director allocated an additional 2 million hours to Randall's group to continue development while Jaguar was off-line for testing.

"These very high-powered computing systems that INCITE is making available are absolutely essential to the project," Randall says. "We could not do this work without them."

For now, Randall says, "the GCRM will do a few simulated weeks at most because computers aren't fast enough to run any longer than that. But in the next couple of years we'll be able to do whole years with the GCRM, 10-second chunks at a time."

In the next 15 years, he predicts, forecasters will "be able to do decades and centuries with models like this."

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