By the late 1980s, Warren Wiscombe, Bob Ellingson and other atmospheric radiation scientists had reached an intractable impasse. Despite their repeated attempts to do otherwise, they simply could not get their radiation models to agree. Not simply an academic conundrum, the skewed models meant that they could not determine with any degree of certainty the effect of atmospheric greenhouse gases on the climate. Was Mother Earth cooling as commonly believed in the 1970s or was she getting warmer – a theory then gaining momentum among climate scientists because the nearly unchanging global-surface temperatures from 1940 to 1975 had begun to rise?

“The bottom line was: How much radiation was getting to the surface? How much was reflected back into space? It was a big unknown,” Wiscombe recalled. “Every radiation model requires input. It would be a pretty simple deal if it weren’t for clouds and aerosols. They are the main reason for the varying global warming results.”

But without hard data to feed the models, the computer calculations would remain the stuff of academic conjecture. Although their models did not agree, scientists working under the auspices of a special program funded by the United States Department of Energy (DOE) – the Intercomparison of Radiation Codes in Climate Models (ICRCCM) – did agree on one point: They needed a field campaign to collect all manner of data that ultimately would improve how computer models dealt with radiative energy transfer and the impact of clouds.

Fast Forward

This winter, that campaign – DOE’s Atmospheric Radiation Measurement (ARM) program – celebrates its 20th anniversary.

Since the program’s launch in 1989, its five permanent research facilities in Oklahoma, the western Pacific, and the north slope of Alaska, along with a mobile station that scientists can dispatch to any location in the world, have provided more than a decade of continuous data, dramatically improving climate models and scientists’ understanding of how to use these models. In short, ARM has become a major contributor to national and international research efforts related to global climate change.

A Matter of Serendipity

For those who were instrumental in conceiving, promoting, and launching the multi-laboratory, interagency program, its anniversary holds special meaning. Its creation, they say, was an act of serendipity, a matter of the right people meeting at the right time and then convincing others of its importance.

To Wiscombe, who now serves part-time as a chief scientist for ARM and a senior research scientist at the Goddard Space Flight Center, its start actually began that day in 1988 when the group of ICRCCM researchers finally agreed that the discrepancy in computer models would never disappear until they developed better code to deal with the cloud problem. And the only way to do this was to collect in situ data with a range of sophisticated sensors placed in strategic, climatically diverse locations.

“I remember, we were frustrated that we couldn’t get our radiation models to agree,” Wiscombe recalled. “Everyone looked at [Ellingson] and me and asked, ‘Why don’t you guys develop a field campaign?”

Initial Concept Developed

The pair had met more than a decade before while carrying out research at the National Center for Atmospheric Research in Boulder. Following through on the recommendation of their peers, Wiscombe and Ellingson put their heads together and conceived an infrared spectrometry experiment and began shopping the idea to DOE because it had funded ICRCCM.

Luckily for them, Robert Hunter then headed DOE’s Office of Energy Research and was casting about for a program that could contribute to the nation’s growing climate-change research efforts.

“Dr. Hunter wanted to make decisions that would make a difference,” recalled Ellingson, who now chairs the Meteorology Department at Florida State University, but is still involved in ARM as the chair of its Science Infrastructure Steering Committee. Hunter assembled a panel of experts and called on scientists to propose ideas. The day after Ellingson presented the data-collection experiment that he and Wiscombe had developed, ‰ÛÏI got a call from Dr. Hunter’s office. He wanted me to come down to meet with him.” As it turned out, “I was the only one who proposed measurements” – something that Hunter agreed was needed and appropriate to DOE’s mission of monitoring greenhouse gases caused by the burning of fossil fuels, Ellingson said.

“It was serendipitous, really,” Ellingson added. Within a few months, Ellingson’s concept to build an experiment to measure the radiation emitted by the atmosphere to the surface and the constituents in the atmosphere above the instruments would grow to include dozens of state-of-the-art radiometer, radar and lidar instruments located at multiple sites around the globe.

Program Evolves

Ellingson and Wiscombe agree that the program’s evolution into a more comprehensive data-gathering effort may not have happened had it not been for Aristides Patrinos, whom Hunter had hired in 1989 to head DOE’s Office of Biological and Environmental Research. “In a sense, I was at the right place, at the right time,” Patrinos agreed. “Bob [Hunter] gave me the responsibility to do whatever we could do in the climate-change research. I looked out at the landscape and saw a glaring omission” – the lack of hard data from climatically diverse locations, he said.

Not everyone in the community, however, agreed that the solution rested with data collection; some believed the purchase of more powerful supercomputers could resolve the discrepancies among radiation models. Others were suspicious of DOE’s commitment to creating a long-term database. “I argued that the problem was a serious one and that ARM could answer questions quickly,” said Patrinos, now the president of Synthetic Genomics, a California-based company that develops and commercializes synthetic biology to address global energy and environmental challenges. “After some pushing and shoving, we eventually got started.”

Expanded Program Launches in 1990

After tapping Ellingson, Gerry Stokes of the Battelle Memorial Institute, and a bevy of other scientific advisors to suggest and peer review different measurement approaches and instrumentation needs, Patrinos officially kicked off an expanded ARM program in 1990. “We created this program in record time. We polled the scientific community in record time. We issued [requests for proposals] in record time. In the early days, it was pretty chaotic,” he said.

By 1992, DOE had opened its first fully instrumented site, the Southern Great Plains (SGP) in Lamont, Oklahoma. Designed to continuously sample all components of the radiation budget at Earth’s surface and in the atmosphere above the site, SGP today is made up of 29 facilities, equipped with 240 instrument systems representing 930 separate sensors and 280 distinct data streams.

Over the succeeding years, DOE’s Office of Biological and Environmental Research added more facilities. In the Pacific, it added facilities on Manus Island in 1996; a second facility on Nauru Island in 1998; and a third facility in Darwin, Australia, in 2002. In 1997, DOE dedicated another permanent site at Barrow, Alaska, the northernmost point in the U.S. at just 330 miles north of the Arctic Circle. A mobile station also has come online.

With $60 million in stimulus money, the program plans to buy more capable, multi-function radar instruments, with the aim of expanding research into the role of precipitation and latent heat in climate change, Wiscombe said. ARM also is adding a marine mobile facility for use on islands, oil platforms, and large ships. “It is another paradigm-busting advance to ARM’s credit,” said Wiscombe, who spearheaded the facility’s development. “Research cruises typically last only a month, while ARM will deploy this new facility for a year or more, allowing the gathering of truly climatic assets.”

In addition, the program is playing a central role in the Global Earth Observation System of Systems (GEOSS), an international program that is developing the infrastructure to connect the producers of environmental data to those who use the data in near real-time. The goal is to enhance the relevance of Earth observations. ‰ÛÏARM is a centerpiece,” Wiscombe added. “It’s an integral part of GEOSS.”

Wiscombe said the ARM program also plans to participate in a joint field campaign with NASA to collect data critical to the development of the space agency’s Global Precipitation Measurement mission, a next-generation Earth-observing satellite constellation that will collect precipitation levels around the globe.

The Final Analysis

To Wiscombe, Ellingson and Patrinos, the program has done more than simply meet its original mandate. “The science benefits go beyond the original intent of the program, which was trying to understand how to represent clouds in the models,” Patrinos said. Not only did scientists improve their models, they made advances in how to use them. ARM data also has helped scientists to ground-truth NASA and National Oceanic and Atmospheric Administration satellite data and improve weather forecasting, an unexpected benefit. It is even considered a model for other nations considering the development of their own data-collection systems.

“It’s so gratifying to see the success of this program,‰Û Patrinos said. “It’s so gratifying to see thousands of publications that are referencing the program and its data,” he continued. “ARM pushed the envelope. It was the first field campaign to gather data over the long term. This is where the program has made the biggest difference.” And to think, he added, that some early critics questioned DOE’s commitment to a sustained program so necessary to climate research. “And here we are after 20 years.”