MODELING POWER:
International teamwork gives a boost to global climate research
NCAR scientist Frank Bryan is studying the impact of the oceans on global climate.
Scientists rely on sophisticated computer models to predict changes in Earth’s climate. But the models require so much computing power that it may take weeks or even months to run a single experiment.
Researchers from NCAR and the nonprofit Central Research Institute of the Electric Power Industry (CRIEPI) in Japan are joining forces to conduct more complex experiments at a greater speed. By re-engineering NCAR’s powerful Community Climate System Model (CCSM), they have improved its performance and its portability. Not only have they made the model faster, but they have also enabled it to perform well on a variety of different supercomputer architectures.
As a result, scientists can run increasingly complex and realistic climate simulations, capturing such small-scale features as ocean eddies and mountain valleys. And the improved portability has enabled NCAR, CRIEPI, and other partners to devise an effective scheme for sharing computational resources, including the Japanese Earth Simulator, which is one of the world’s most powerful machines.
The collaboration provides benefits to both the United States and Japan. NCAR scientists are attempting to better predict future variations in climate, while Japanese researchers, in addition to studying global conditions, are trying to determine whether climate change will alter typhoon patterns or spur rising sea levels that could affect the nation’s coastal communities.
“This collaboration is enabling us to examine our future climate in unprecedented detail,” says NCAR scientist Frank Bryan.
A high number of experiments
One of the world’s premier climate models, the CCSM is the product of years of cooperation among scientists at NCAR, Department of Energy labs, and U.S. universities, as well as numerous universities and labs in other nations. It incorporates the interactions of the atmosphere, oceans, sea ice, and land cover. By taking into account factors ranging from clouds to atmospheric chemistry to the impacts of snow cover and vegetation, it provides a comprehensive picture of the climate system and how it is changing.
NCAR and CRIEPI scientists, using NCAR supercomputers, the Earth Simulator, and machines at several Department of Energy centers, have been able to conduct an unusually high number of climate experiments over the past several years. The experiments will be used for the much-anticipated 2007 Intergovernmental Panel on Climate Change (IPCC) assessment, which will provide an update on the expected climatic impacts of increasing amounts of greenhouse gases in the atmosphere. (For more on NCAR and IPCC, see Global Research.)
Each experiment begins with different initial conditions (an El Niño situation of warm surface waters in certain parts of the Pacific Ocean, for example). By running a large ensemble of experiments that each start with different conditions, scientists can obtain a more statistically robust picture of climate change.
The experiments also are more far reaching. Because of limited supercomputer resources, most of NCAR’s experiments have simulated climate change only until 2100, when atmospheric levels of carbon dioxide may be more than twice as high as in the preindustrial age. Now, however, scientists can simulate climate as far into the future as 2450. This will enable them to investigate longer-term changes, such as the sea level rise that plays out over several centuries or the effect on global climate if carbon dioxide levels start to decline after 2100.
Eddies and mountains
The next step in the collaboration will be the creation of a higher-resolution version of the CCSM, which will enable experiments with far more fine-scale detail. Early progress on the ocean component of the CCSM is already permitting scientists to simulate and study eddies in the ocean that, while just a few tens of kilometers across, transport energy and properties such as salinity in ways that profoundly affect climate.
By using more computer power, the CCSM can produce especially detailed simulations. The image on the left estimates the broad-scale movement of water around South Africa’s Cape of Good Hope. The image on the right, produced by the Earth Simulator, captures much more detail and indicates how heat and salt can move in isolated structures known as Agulhas rings.
As the resolution of the CCSM’s land component is increased, it will be possible to incorporate more detailed information about topographic features such as mountain ranges and valleys to gain insights into regional climate. Instead of rounding off the height of Washington’s Olympic mountains to about 5,000 feet (1,500 meters) for example, the model run on the Earth Simulator can more closely incorporate the height of the mountain range, which reaches nearly 8,000 feet (2,400 meters). This will enable researchers to more correctly capture the amount of precipitation that falls as snow as opposed to rain—thereby allowing them to estimate spring and summer water supply from melting snow. And increased resolution in the model’s atmosphere component holds the promise of more information about tropical storms.
The result will be an unprecedented picture of Earth’s changing climate. As Bryan says, “We will be able to capture regional impacts of climate change that were previously beyond our capabilities.”
Flying in and out of Taiwan can be challenging because the island’s mountains and the surrounding ocean often contribute to adverse weather conditions. To bolster air safety, the Taiwan Civil Aeronautics Administration selected NCAR in the late 1990s to create a new weather information and warning system for the island.
The resulting Advanced Operational Aviation Weather System (AOAWS) is helping to safeguard aircraft against weather threats such as tropical cyclones, major thunderstorms, in-flight icing, and turbulence. Pilots, controllers, forecasters, and other users can chart a flight route within Taiwan’s airspace, obtain hazardous weather information, and gather routine data and forecasts along that route.
Taiwan experts study NCAR's weather information and warning system.
“This is a true technology transfer success story,” says NCAR scientist William Mahoney, who helped oversee the project. “Taiwan now has state-of-the-art aviation weather technology that far surpasses international safety standards.”
The system relies on a powerful computer forecasting model, as well as such instruments as Doppler weather radars, Low Level Wind Shear Alert System sensors, satellites, aircraft reports, and the Taiwan lightning detection network. NCAR will expand the system in 2006: new capabilities will include thunderstorm nowcasting and the addition of an NCAR computer model that provides an exceptionally detailed picture of the atmosphere.
More Asian Collaborations:
Tracking Pollution Across Continents
Overview | Asia | Middle East/Africa | Oceania/Antarctica | Europe | The Americas | Global Research
