Climate modeling at ORNL

Jamison Daniel/National Center for Computational Sciences

I’m a fool for pretty pictures, and there’s some cool-looking stuff coming out of the climate modeling programs at ORNL. The above map shows the instantaneous “net ecosystem exchange” (NEE) from a global climate simulation.

Forrest Hoffman of ORNL’s computational Earth sciences group explains:

“In this case, the Western Hemisphere is facing the sun, so what we see is a strong negative NEE (shown in green) in which vegetation is taking up CO2 from the atmosphere through photosynthesis. The yellow areas are taking up less CO2 because of low sun angle (e.g., Northern Canada), less vegetation (e.g., in the Western U.S.) or because of the seasonal cycle (e.g., parts of South America).”

Hoffman added: “I believe this snapshot was created for the month of July from our simulation, so it is summer in the Northern Hemisphere and winter in the Southern Hemisphere.”

He said the snapshop here is similar to animation that highlights tropical forests at this site:

“That animation shows a net release of CO2 from the biosphere (i.e., a positive NEE), primarily in the evening, in red and an uptake of CO2 by the biosphere (i.e., a negative NEE) in green. The colors change as the sun rises and sets. The CO2 release in the evening is primarily the result of heterotrophic respiration, which comes from microbes and other organisms that decompose litter (e.g., leaves, woody debris, dead roots, etc.) and soil.”

For more information on the C-LAMP project, check out this site.

Hoffman said all simulations that ORNL performed for the C-LAMP project, including those used for visualizations, were run on “Phoenix” — a Cray X1E — from 2006 through early 2008.

He said the computer has a unique architecture, with custom-designed vector processors, but a peak performance of only 18.5 trillion calculations per second. He said the computer is scheduled to be decommissioned Sept. 30.

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About Frank Munger

Senior Writer Frank Munger covers the Dept. of Energy's Oak Ridge facilities and many related topics — nuclear weapons, nuclear waste and other things nuclear, environmental cleanup and science of all sorts. Atomic City Underground is, first and foremost, a news blog, but there's room for analysis, opinion and random thoughts that have no place else to go.


  1. Sean says:

    Next time you come to ORNL, you should see our movie of this over time on the EVEREST powerwall, Frank.

  2. Frank Munger says:

    Thanks, Sean. I’ll do it.