Tiny particles that form seed clouds can form from stems over an open sea

UPTON, NY – New findings from an atmospheric study across the Atlantic Ocean suggest that tiny aerosol particles that propagate cloud formation can form zero-to-zero emissions. open ocean. This “new formation of grains” occurs when sunlight reacts with molecules of systemic gases in the sea boundary cover, the indoor atmosphere about the first kilometer above the surface of the sea. Land. The findings, published in the journal Nature Communication, will develop the representation of aerosols and clouds in models that describe the Earth ‘s climate so that scientists can understand how the grains – and the processes that regulate them – can affect bring the planet past and present, and make better predictions about the future.

“When we say ‘the formation of new particles’, we are talking about individual gas molecules, sometimes just a few atoms in size, reacting with sunlight,” said study co-author Congai Kuang, a member of the study. of the Department of Environmental and Climate Sciences at the Brookhaven National Laboratory of the U.S. Department of Energy. “It’s interesting to think about how something of that scale will have such a profound effect on our climate – on the amount of energy on it. reflected or captured in our atmosphere, “he said.

But modeling is the details of how aerosol particles shape and grow, and how water molecules wake up on them to become droplets and clouds, while at the same time ‘consider the effect of different aerosol properties (eg, size, number and spatial distribution) on these processes. very complicated – especially if you don’t know where the aerosols come from. So a team of scientists from Brookhaven and colleagues in atmospheric research around the world aimed to collect data in a somewhat pristine ocean environment. In that case, they expected that the low gas concentration and cloud formation would be particularly sensitive to aerosol buildups – a very suitable “laboratory” for the removal of inter- complex operations.

“This was a test that gave Brookhaven a very broad and collaborative experience in aerosol and cloud observation,” Kuang said. Three of the principal investigators – lead authors Guangjie Zheng and Yang Wang, and Jian Wang, principal investigator of the Aerosol and Cloud initiative in the Northeast Atlantic (ACE-ENA) – became involved with the project while worked at Brookhaven and have been close collaborators with the Lab since moving to Washington University in St. Louis. Louis in 2018.

Land and sea

The study used a ground-based long-range sampling station on Graciosa Island in the Azores (an island 850 miles west of mainland Portugal) and a clothed Gulfstream-1 aircraft with 55 atmospheric instrumentation systems to measure at different altitudes. on 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, managed and operated by a consortium of nine DOE national laboratories.

The crew flew the planes on “porpoise planes,” ascending and descending through the border to obtain direct images of the pre-existing particles and gas molecules present at different altitudes. And they were coordinating those flights with measurements taken from the ground station.

The scientists did not expect the formation of new grains to occur in the boundary phase in this environment because they expected that the concentration of the detection gases would be too low.

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

The dimensions of the planes gave them the answer.

“This plane had unique flight patterns during the measurement campaign,” Kuang said. “They saw evidence that the formation of new grains occurred above – not at the surface but at the upper boundary level.” The evidence included a mixture of high concentrations of small, low-density grains of pre-existing aerosol coatings, and clear signs that reactive detection gases such as dimethyl sulfide were transported directly – along with atmospheric conditions favorable for these gases to respond. sunlight.

“Then, once these aerosol grains form, they attract additional gas molecules, which condense and cause the grains to grow to about 80-90 nanometers in diameter. These large particles then carry them down – and that ‘s what we measure at the surface, “Kuang said.

“The surface measurements as well as the flight measurements give us a very good wide-ranging awareness of the aerosol processes taking place,” he said.

At a certain size, the particles grow large enough to attract water mist, which coalesce to form droplets of clouds, and eventually clouds.

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

Impact of research

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

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

Another important question: “If this is such a clean environment, where do these superconducting gases come from?” Kuang asked. “Some important precursor gases are generated by biological activity in the ocean (e.g., dimethyl sulfide) which can lead to the formation of new granules. That can be a nice follow-up study to this one – study of these sources. “

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

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

Brookhaven National Laboratory is supported by the U.S. Department of Energy’s Office of Science. The Office of Science is the single largest supporter of fundamental research in the physical sciences in the United States, and is working to address some of the most important challenges of our time. For more information, visit science.energy.gov.

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Related Links

An online version of this press release with illustrations and graphics

Scientific paper: “Creation of new particles in the remote marine frontier stage”

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Karen McNulty Walsh [mailto:[email protected]], (631) 344-8350, and Peter Genzer [mailto:[email protected]], (631) 344-3174