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Chongai Kuang

From left, Shawn Serbin, Scott Giangrande and Chongai Kuang. Photo from Brookhaven National Laboratory

By Daniel Dunaief

Chongai Kuang is doing considerably more than standing in the middle of various fields throughout the southeast, looking up into the sky, sticking his finger in the air and taking notes on the potential appeal of the area.

Entrusted with finding the right spot for the third ARM Mobile Facility, or AMF3, Kuang, who is an Atmospheric Scientist in the Environmental & Climate Sciences Department at Brookhaven National Laboratory, is gathering considerable amounts of information about different areas in the southeast.

In March of 2023, the ARM3 mobile facility, which has been operating in Oliktok Point, Alaska, will have a new home, where it can gather information about atmospheric convection, land-atmosphere interactions and aerosol processes.

In addition to finding the right location for this facility, Kuang will coordinate with the larger science community to make recommendations to ARM for observations, measurements, instruments and sampling strategies. Observations from these fixed and mobile facilities will improve and inform earth system models.

Kuang would like to find a strategic place for the AMF3 that is “climactically relevant to provide important observations on clouds, aerosols, and land atmosphere interactions that are needed to answer science drivers” important in the southeastern United States, Kuang said. These facilities will help researchers understand how all these atmospheric phenomena interact with solar radiation and the Earth’s surface.

The AMF3 should provide information that informs climate, regional and weather models.

In 2018, the Department of Energy, which funds BNL and 16 other national laboratories, held a mobile facility workshop to determine where to move the AMF3. The group chose the Southeastern United States because it has atmospheric convection, high vegetative-driven emissions and strong coupling of the land surface with the atmosphere. This area also experiences severe weather including tornadoes and hurricanes, which have significant human and socioeconomic impacts, said Kuang.

The most violent weather in the area often “tests the existing infrastructure,” Kuang said. “This deployment can provide critical observations and data sets,” in conjunction with regional operational observational networks.

Atmospheric phenomena as a whole in the southeastern United States includes processes and interactions that span spatial scales ranging from nanometers to hundreds of kilometers and time scales spanning seconds to days.

Kuang’s primary research interests over the past decade has focused on aerosol processes at nanometer scales, as he has studied the kinds of miniature aerosol particles that form the nuclei for cloud formation. These aerosols affect cloud lifetime and spatial distribution.

“Our research is challenged by disparate scales relevant to phenomena we’re trying to characterize, from nanometers to the length scale of convective systems, which are tens of kilometers or even larger,” Kuang said. These scales also present opportunities to study coupled science with convection, aerosol and land-atmosphere interactions.

The ARM observatories around the world provide atmospheric observations of aerosols, clouds, precipitation and radiation to inform and improve Earth system models.

“We are going to leverage as much as we can of the existing networks,” Kuang said. The ARM has a fixed site in Oklahoma, which provides data for the Southern Great Plains Site, or SGP. The Southeastern site, wherever it winds up, will provide a context for large-scale atmospheric phenomena.

The way aerosols, clouds and weather systems form and change presents a challenge and an opportunity for research stations like AMF3, which will seek to connect phenomenon at spatial and time scales that affect where Kuang and his team hope to locate the site.

Kuang is also staying abreast of the latest technology and is also contributing to the development of these capabilities. The technology the AMF3 may use could be developed between now and when the site starts gathering data.

“We have the opportunity now to start thinking about what the next generation measurement capabilities and emerging technologies are that could be operational in 2023,” he said. “We are in conversations with the broader community and with different vendors and with a number of different investigators who are developing new technologies.”

Researchers hope to understand the coupling between the land surface and atmospheric phenomenon. “That will have feedback on radiation and precipitation and the impact on land-surface interactions,” Kuang explained. The current plan is for the new facility to operate for about five years.

While Kuang is focused on the scientific drivers for the site selection, he has also been exploring the dynamic with potential research partners, including universities, seeking ways to add educational partners.

“We have hopes and plans for this kind of deliberate, targeted outreach within the region,” Kuang said. “We want to organize activities like summer school, to provide young scientists with primers and an introduction about how observations are made within their backyard.”

The work he’s trying to do now is “setting the table and preparing the soil for the eventual siting” of the station.

Kuang will measure his success if the new site improves poorly represented model processes.

Once the DOE chooses a site, Kuang plans to develop and execute an initial science plan that uses AMF3 observations. As an ARM instrument mentor, he will also be responsible for a set of instruments that measure aerosol size and concentration.

A resident of Wading River, Kuang started working at BNL in 2009 as a postdoctoral researcher. When he’s not working, he describes cooking as “therapeutic,” as he and his wife, Anyi Hsueh, who is a psychiatric nurse practitioner, have explored Southeastern Asian and Middle Eastern cuisines.

Kuang is working with Associate Ecologist Shawn Serbin and Meteorologist Scott Giangrande, in site selection. The work presents an “important responsibility and our site science team envisions the AMF3 southeastern united States [site] to enable transformational science,” he said.

Results from a study of clouds and aerosols conducted in the Azores revealed that new particles can seed the formation of clouds in the marine boundary layer—the atmosphere up to about a kilometer above Earth's surface—even over the open ocean, where the concentration of precursor gases was expected to be low. Image courtesy of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility.

Understanding previously undocumented source of new particle formation will improve models of aerosols, clouds, and their impact on Earth’s climate

New results from an atmospheric study over the Eastern North Atlantic reveal that tiny aerosol particles that seed the formation of clouds can form out of next to nothingness over the open ocean. This “new particle formation” occurs when sunlight reacts with molecules of trace gases in the marine boundary layer, the atmosphere within about the first kilometer above Earth’s surface. The findings, published in the journal Nature Communications, will improve how aerosols and clouds are represented in models that describe Earth’s climate so scientists can understand how the particles—and the processes that control them—might have affected the planet’s past and present, and make better predictions about the future.

“When we say ‘new particle formation,’ we’re talking about individual gas molecules, sometimes just a few atoms in size, reacting with sunlight,” said study co-author Chongai Kuang, a member of the Environmental and Climate Sciences Department at the U.S. Department of Energy’s Brookhaven National Laboratory. “It’s interesting to think about how something of that scale can have such an impact on our climate—on how much energy gets reflected or trapped in our atmosphere,” he said.

Using an aircraft outfitted with 55 atmospheric instrument systems, scientists traversed horizontal tracks above and through clouds and spiraled down through atmospheric layers to provide detailed measurements of aerosols and cloud properties. The aircraft data were supplemented by measurements made by ground-based radars and other instruments. Image courtesy of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility.

But modeling the details of how aerosol particles form and grow, and how water molecules condense on them to become cloud droplets and clouds, while taking into consideration how different aerosol properties (e.g., their size, number, and spatial distribution) affect those processes is extremely complex—especially if you don’t know where all the aerosols are coming from. So a team of scientists from Brookhaven and collaborators in atmospheric research around the world set out to collect data in a relatively pristine ocean environment. In that setting, they expected the concentration of trace gases to be low and the formation of clouds to be particularly sensitive to aerosol properties—an ideal “laboratory” for disentangling the complex interactions.

“This was an experiment that really leveraged broad and collaborative expertise at Brookhaven in aerosol observations and cloud observations,” Kuang said. Three of the lead researchers—lead authors Guangjie Zheng and Yang Wang, and Jian Wang, principal investigator of the Aerosol and Cloud Experiments in the Eastern North Atlantic [https://www.arm.gov/publications/backgrounders/docs/doe-sc-arm-16-020.pdf] (ACE-ENA) campaign—began their involvement with the project while working at Brookhaven and have remained close collaborators with the Lab since moving to Washington University in St. Louis in 2018.

Land and sea

Brookhaven Lab atmospheric scientist Chongai Kuang (center) with Art Sedlacek (left) and Stephen Springston (right) aboard ARM’s Gulfstream-159 (G-1) aircraft during a 2010 atmospheric sampling mission that was not part of this study. Image courtesy of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility.

The study made use of a long-term ground-based sampling station on Graciosa Island in the Azores (an archipelago 850 miles west of continental Portugal) and a Gulfstream-1 aircraft outfitted with 55 atmospheric instrument systems to take measurements at different altitudes over the island and out at sea. Both the ground station and aircraft belong to the DOE Office of Science’s Atmospheric Radiation Measurement (ARM) user facility [https://www.arm.gov/], managed and operated by a consortium of nine DOE national laboratories.

The team flew the aircraft on “porpoise flights,” ascending and descending through the boundary layer to get vertical profiles of the particles and precursor gas molecules present at different altitudes. And they coordinated these flights with measurements taken from the ground station.

The scientists hadn’t expected new particle formation to be happening in the boundary layer in this environment because they expected the concentration of the critical precursor trace gases would be too low.

“But there were particles that we measured at the surface that were larger than newly formed particles, and we just didn’t know where they came from,” Kuang said.

The aircraft measurements gave them their answer.

Many of the choreographed flight paths for this study traversed the open ocean and also crossed within the ranges of the ground-based scanning radars at DOE’s Atmospheric Radiation Measurement (ARM) Climate Research Facility on Graciosa Island in the Azores. Image courtesy of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility.

“This aircraft had very specific flight patterns during the measurement campaign,” Kuang said. “They saw evidence that new particle formation was happening aloft—not at the surface but in the upper boundary layer.” The evidence included a combination of elevated concentrations of small particles, low concentrations of pre-existing aerosol surface area, and clear signs that reactive trace gases such as dimethyl sulfide were being transported vertically—along with atmospheric conditions favorable for those gases to react with sunlight.

“Then, once these aerosol particles form, they attract additional gas molecules, which condense and cause the particles to grow to around 80-90 nanometers in diameter. These larger particles then get transported downward—and that’s what we’re measuring at the surface,” Kuang said.

“The surface measurements plus the aircraft measurements give us a really good spatial sense of the aerosol processes that are happening,” he noted.

At a certain size, the particles grow large enough to attract water vapor, which condenses to form cloud droplets, and eventually clouds.

Both the individual aerosol particles suspended in the atmosphere and the clouds they ultimately form can reflect and/or absorb sunlight and affect Earth’s temperature, Kuang explained.

Study implications

Framed by a brilliant rainbow, ARM’s Gulfstream-159 (G-1) research aircraft sits on the tarmac on Terceira Island during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) winter 2018 intensive operation period in the Azores. Image courtesy of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility.

So now that the scientists know new aerosol particles are forming over the open ocean, what can they do with that information?

“We’ll take this knowledge of what is happening and make sure this process is captured in simulations of Earth’s climate system,” Kuang said.

Another important question: “If this is such a clean environment, then where are all these precursor gases coming from?” Kuang asked. “There are some important precursor gases generated by biological activity in the ocean (e.g., dimethyl sulfide) that may also lead to new particle formation. That can be a nice follow-on study to this one—exploring those sources.”

Understanding the fate of biogenic gases such as dimethyl sulfide, which is a very important source of sulfur in the atmosphere, is key to improving scientists’ ability to predict how changes in ocean productivity will affect aerosol formation and, by extension, climate.

The research was funded by the DOE Office of Science, DOE’s Atmospheric System Research, and by NASA. In addition to the researchers from Brookhaven Lab and Washington University, the collaboration included scientists from Pacific Northwest National Laboratory; Missouri University of Science and Technology; the University of Washington, Seattle; NASA Langley Research Center; Science Systems and Applications Inc. in Hampton, Virginia; the Max Planck Institute for Chemistry in Mainz, Germany; and the Scripps Institution of Oceanography, University of California, San Diego.

Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy.  The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.  For more information, please visit science.energy.gov [https://www.energy.gov/science/office-science].