[asa] NASA - Climate Simulation Computer Becomes More Powerful

http://www.nasa.gov/topics/earth/features/climate_computing.html

Climate Simulation Computer Becomes More Powerful08.24.09

Remember the day you got a brand-new computer? Applications snapped
open, processes that once took minutes finished in seconds, and
graphics and animation flowed as smoothly as TV video. But several
months and many new applications later, the bloom fell off the rose.

Your lightning-fast computer no longer was fast. You needed more
memory and faster processors to handle the gigabytes of new files now
embedded in your machine.

Climate scientists can relate.

They, too, need more powerful computers to process the sophisticated
computer models used in climate forecasts. Such an expanded capability
is now being developed at NASA’s Goddard Space Flight Center in
Greenbelt, Md.

High-End Computing System Installed

In August, Goddard added 4,128 new-generation Intel "Nehalem"
processors to its Discover high-end computing system. The upgraded
Discover will serve as the centerpiece of a new climate simulation
capability at Goddard. Discover will host NASA’s modeling
contributions to the Intergovernmental Panel on Climate Change (IPCC),
the leading scientific organization for assessing climate change, and
other national and international climate initiatives.

To further enhance Discover’s capabilities, Goddard will install
another 4,128 Nehalem processors in the fall, bringing Discover to
15,160 processors.

"We are the first high-end computing site in the United States to
install Nehalem processors dedicated to climate research," said Phil
Webster, chief of Goddard’s Computational and Information Sciences and
Technology Office (CISTO). "This new computing system represents a
dramatic step forward in performance for climate simulations."

Well-Suited for Climate Studies

According to CISTO lead architect Dan Duffy, the Nehalem architecture
is especially well-suited to climate studies. "Speed is an inherent
advantage for solving complex problems, but climate models also
require large memory and fast access to memory," he said. Each
processor has 3 gigabytes of memory, among the highest available
today. In addition, memory access is three to four times faster than
Discover’s previous-generation processors.

In preliminary testing of Discover’s Nehalem processors, NASA climate
simulations performed up to twice as fast per processor compared with
other nationally recognized high-end computing systems. The new
computational capabilities also allowed NASA climate scientists to run
high-resolution simulations that reproduced atmospheric features not
previously seen in their models.

For instance, "features such as well-defined hurricane eyewalls and
convective cloud clusters appeared for the first time," said William
Putman, acting lead of the Advanced Software Technology Group in
Goddard’s Software Integration and Visualization Office. "At these
cloud-permitting resolutions, the differences are stunning."

IPCC Simulations

For the IPCC studies, scientists will run both longer-term and shorter-
term climate projections using different computer models. A climate
model from the Goddard Institute for Space Studies will perform
simulations going back a full millennium and forward to 2100.
Goddard’s Global Modeling and Assimilation Office will use a climate
model for projections of the next 30 years and an atmospheric
chemistry-climate model for short-term simulations of chemistry-
climate feedbacks. The IPCC will use information from climate
simulations such as these in its Fifth Assessment Report, which IPCC
expects to publish in 2014.

NASA climate simulation efforts also contribute to the U.S. Global
Change Research Program, the U.S. Integrated Earth Observation System,
and the U.S. Weather Research Program. Supported international
programs include UNESCO’s Intergovernmental Oceanographic Commission,
the United Nations Environment Programme, the World Climate Research
Programme, the World Meteorological Organization, and the World
Weather Research Programme.

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The new computer setup can simulate using a 3.5 km grid size. Compare  
the following:
Climate simulation output with a 27 km grid:
http://www.nasa.gov/images/content/381019main_27km_lg.jpg
Climate simulation output with a 3.5 km grid:
http://www.nasa.gov/images/content/381020main_3-5km_lg.jpg
The actual clouds from the GOES-O satellite:
http://www.nasa.gov/images/content/381021main_GOES-O.jpg
Now look at a complex simulation of a cloud around the Aleutian  
Islands known as a von Karman Vortex Street. A vortex street is a  
train of alternating clockwise and anticlockwise eddies. Here's the  
simulation given the different grid sizes again with the smaller size  
due to the new compute power.
http://www.nasa.gov/images/content/380997main_Vortex_Streets_lg.jpg
Finally a picture of what this bad boy looks like:
http://www.nasa.gov/images/content/380996main_Discover_Expansion_lg.jpg
Rich Blinne
Member ASA
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