ARM CARTs reduce climate change uncertainty

Climate-change data from Argonne-managed facilities are improving scientists’ ability to predict climate trends.

Argonne oversees three outdoor weather laboratories called Cloud and Radiation Testbed (CART) sites. The CART sites — Southern Great Plains in Kansas and Oklahoma, the Tropical Western Pacific covering Australia, Papua New Guinea and Nauru, and the North Slope of Alaska — provide the foundation for the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) program.

The ARM program supplies data to researchers to improve General Circulation Models that are used to forecast climate change. These models are designed to simulate important meteorological conditions that affect climate over 50,000-square-mile grids, the smallest area that can reasonably be handled by today’s computers. Each CART site supplies data from a grid where specific atmospheric processes dominate in determining how much of the sun’s energy reaches the Earth’s surface.

REFINING RESEARCH
Recent research by Tony Del Genio of NASA’s Goddard Institute for Space Studies, funded by NASA and ARM, demonstrates ARM’s impact on meteorological research.

Using new understanding gained about the warming and cooling properties of clouds from ARM data, Del Genio reduced the uncertainty of models used to predict temperature changes due to the potential doubling of atmospheric carbon dioxide. Previously, the model’s predictions were uncertain to within a range of 1.5 to 4.5 degrees Celsius — a small range for humans, but a huge range for world climate. But by using the improved models, Del Genio reduced that uncertainty by 50 percent to 2.5 to 4 degrees Celsius.

"Compensating for even one degree of increased global warming is a huge challenge, especially when setting policy or planning mitigation strategies," said Doug Sisterson, an Argonne scientist and operations manager for the three ARM sites.

Sisterson believes this study proves how valuable ARM data can be to the modeling community. "This is how ARM data are intended to be used," he said.

CENTRALIZING CART OPERATIONS
In 2000, DOE centralized CART operations and named Argonne’s Sisterson to be operations manager. Previously, Sisterson developed and managed the first ARM site, the Southern Great Plains facility. Sandia National Laboratories manages the North Slope of Alaska site, Los Alamos National Laboratory maintains the Tropical Western Pacific site and Argonne’s Jim Liljegren now runs the Southern Great Plains facility.

"The ARM program is not taking sides on warming or cooling," said Sisterson, "but it’s trying to reduce the uncertainty about climate change by providing researchers with high quality data to study."

Data are collected continuously at the three sites. Each site’s data system is linked by high-speed communication to the ARM Data Management Facility at Pacific Northwest National Laboratory, the ARM Data Archive at Oak Ridge National Laboratory and the External Data Center at Brookhaven National Laboratory. "All these data are free to any scientist in the world," said Sisterson.

And those data are starting to make their way to the mainstream of users, according to Sisterson. The European Numerical Prediction Center, for example, routinely uses ARM data to improve its medium-range weather forecasts. The National Weather Service collects real-time data from the Tropical Western Pacific site and more frequent data from the North Slope of Alaska site; both are areas of the world they did not receive readings from previously. ARM data can be viewed via the Internet at www.arm.gov.

The ARM program is supported by the Department of Energy’s Office of Science, Office of Biological and Environmental Research, Environmental Sciences Division.

For more information please contact Donna Jones Pelkie