The 91探花鈥檚 College of the Environment will expand its work related to climate solutions thanks to a grant announced today from , FFST, a new foundation within the Paul G. Allen philanthropic ecosystem.

The College of the Environment will use the $10 million grant from FFST to deepen its work in researching climate solutions, climate prediction and environmental monitoring through field observation and data modeling.

鈥淥ur mission is to enable accelerated discovery and catalyze progress through transformational science and technology,鈥� said Dr. Lynda Stuart, FFST鈥檚 chief executive officer. 鈥淲e need more solutions for some of the most defining challenges of our time, which is why the foundation is focused on bioscience, a range of environmental issues, and the role AI can play to benefit people and the planet. These were three priority areas for Paul Allen, and our early grantees are at the forefront of that work.鈥�

The College of the Environment is the largest environment-focused institute of higher learning in the United States. College of the Environment faculty include globally recognized experts in atmospheric and climate science, geology, forestry, oceanography, fisheries, marine policy and more.

鈥淭his generous support from听FFST represents a vital investment in the 91探花College of the Environment, strengthening our ability to drive the research, discovery and solutions required to address the most pressing climate challenges of our time,鈥� said 91探花President Robert J. Jones. 鈥淭he 91探花 is deeply grateful for our long-standing relationship with the Paul G. Allen philanthropic ecosystem, and to Dr. Stuart and her team for their vision and commitment to advancing this critical work.鈥�

Through the grant, researchers will build on strengths in the atmospheric and ocean sciences that can be applied to climate solutions, climate prediction and environmental monitoring through robust field observations and theoretical and AI-based modeling. College of the Environment experts hope to gain a better understanding of climate and ecosystem health, which in turn supports the health and wellbeing of all Earth鈥檚 inhabitants.

鈥淪upport from FFST will drive research that transcends traditional boundaries to tackle the urgent challenges of our rapidly changing environment,鈥� said , associate dean of research and program lead at the College of the Environment. 鈥淲orking across scientific disciplines allows us to understand the truly complex nature of these changes and helps us develop the tools that could potentially mitigate them.鈥�

This investment comes at a critical time for environmental science, when support across the funding landscape is uncertain. 鈥淲e are deeply grateful to FFST for their support of the 91探花and the College of the Environment,鈥� Interim Dean said. 鈥淭his investment will ensure we can continue to discover and understand our world, and to pursue bold and innovative solutions to the environmental challenges we face by leveraging the breadth of expertise across the College, the 91探花and our region.鈥�

For more information about FFST, read . Contact John Meyer at the College of the Environment at jjmeyer@uw.edu.

Thornton will step into the position vacated by Maya Tolstoy, who recently announced she is leaving the UW.

As professor and chair of the Department of Atmospheric and Climate Science, Thornton is an atmospheric chemist. He studies the impacts of human activities on air quality and climate through changes to the atmosphere鈥檚 composition and chemistry. Thornton has received an NSF CAREER Award and a NASA New Investigator Award, given to young researchers who show exceptional promise. He also received the Houghton Award from the American Meteorological Society and the ASCENT Award from the American Geophysical Union for his research contributions to the field of atmospheric science.

Serio said that a search advisory committee will be appointed to launch a national search for a new dean this fall.

A team led by researchers at the 91探花 has discovered a major cause for a drop in nighttime pollinator activity 鈥� and people are largely to blame.

The researchers found that nitrate radicals (NO3) in the air degrade the scent chemicals released by a common wildflower, drastically reducing the scent-based cues that nighttime pollinators rely on to locate the flower. In the atmosphere, NO3 is produced by chemical reactions among other nitrogen oxides, which are themselves released by the combustion of gas and coal from cars, power plants and other sources. The findings, Feb. 9 in the journal Science, are the first to show how nighttime pollution creates a chain of chemical reactions that degrades scent cues, leaving flowers undetectable by smell. The researchers also determined that pollution likely has worldwide impacts on pollination.

The team 鈥� co-led by , a 91探花professor of biology, and , a 91探花professor of atmospheric sciences 鈥� studied the (Oenothera pallida). This wildflower grows in arid environments across the western U.S. They chose this species because its white flowers emit a scent that attracts a diverse group of pollinators, including nocturnal moths, which are one of its most important pollinators.

At field sites in eastern Washington, the researchers collected scent samples from pale evening primrose flowers. Back in the laboratory, they used chemical analysis techniques to identify the dozens of individual chemicals that make up the wildflower鈥檚 scent.

鈥淲hen you smell a rose, you鈥檙e smelling a diverse bouquet composed of different types of chemicals,鈥� said Riffell. 鈥淭he same is true for almost any flower. Each has its own scent made up of a specific chemical recipe.鈥�

Once they had identified the individual chemicals that make up the wildflower鈥檚 scent, the team used a more advanced technique called mass spectrometry to observe how each chemical within the scent reacted to NO3. They found that reacting with NO3 nearly eliminated certain scent chemicals. In particular, the pollutant decimated levels of monoterpene scent compounds, which in separate experiments moths found most attractive.

Moths, which smell through their antennae, have a scent-detection ability that is roughly equivalent to dogs 鈥� and several thousand times more sensitive than the human sense of smell. Research suggests that several moth species can detect scents from miles away, according to Riffell.

Using a wind tunnel and computer-controlled odor-stimulus system, the team investigated how well two moth species 鈥� the (Hyles lineata) and the (Manduca sexta) 鈥� could locate and fly toward scents. When the researchers introduced the pale evening primrose鈥檚 normal scent, both species would readily fly toward the scent source. But when the researchers introduced the scent and NO3 at levels typical for a nighttime urban setting, Manduca鈥檚 accuracy dropped by 50% and Hyles 鈥� one of the chief nocturnal pollinators of this flower 鈥� could not locate the source at all.

Experiments in a natural setting backed up these findings. In field experiments, the team showed that moths visited a fake flower emitting unaltered scent as often as they visited a real one. But, if they treated the scent first with NO3, moth visitation levels dropped by as much as 70%.

鈥淭he NO3 is really reducing a flower鈥檚 鈥榬each鈥� 鈥� how far its scent can travel and attract a pollinator before it gets broken down and is undetectable,鈥� said Riffell.

The team also compared how daytime and nighttime pollution conditions impacted the wildflower鈥檚 scent chemicals. Nighttime pollution had a much more destructive effect on the scent鈥檚 chemical makeup than daytime pollution. The researchers believe this is largely due to sunlight degrading NO3.

The team used a computer model that simulates both global weather patterns and atmospheric chemistry to locate areas most likely to have significant problems with plant-pollinator communication. The areas identified include western North America, much of Europe, the Middle East, Central and South Asia, and southern Africa.

鈥淥utside of human activity, some regions accumulate more NO3 because of natural sources, geography and atmospheric circulation,鈥� said Thornton, who added that natural sources of NO3 include wildfires and lightning. 鈥淏ut human activity is producing more NO3 everywhere. We wanted to understand how those two sources 鈥� natural and human 鈥� combine and where levels could be so high that they could interfere with the ability of pollinators to find flowers.鈥�

The researchers hope their study is just the first of many to help uncover the full scope of pollinator failure.

鈥淥ur approach could serve as a roadmap for others to investigate how pollutants impact plant-pollinator interactions, and to really get at the underlying mechanisms,鈥� said Thornton. 鈥淵ou need this kind of holistic approach, especially if you want to understand how widespread the breakdown in plant-pollinator interactions is and what the consequences will be.鈥�

The study highlights the dangers of human-fueled pollution and its implications for all pollinators as well as the future of agriculture.

鈥淧ollution from human activity is altering the chemical composition of critical scent cues, and altering it to such an extent that the pollinators can no longer recognize it and respond to it,鈥� said Riffell.

Approximately three-quarters of the more than 240,000 species of flowering plants rely on pollinators, Riffell said. And more than听70 species of pollinators are endangered or threatened.

Lead author on the paper is Jeremy Chan, a postdoctoral researcher at the University of Copenhagen who conducted this study as a 91探花doctoral student in biology. Co-authors are Sriram Parasurama in the 91探花Department of Biology; Rachel Atlas, a postdoctoral researcher at the Pierre Simon Laplace Institute in France who participated in this study as a 91探花doctoral student in atmospheric sciences; , a 91探花doctoral students in atmospheric sciences; Ruochong Xu, a doctoral student at Tsinghua University in China; , a 91探花professor of atmospheric sciences; and , a professor of chemistry at Seattle University. The research was funded by the Air Force Office of Scientific Research, the National Science Foundation, the National Institutes of Health, the Human Frontiers in Science Program, and the 91探花.

For more information, contact Riffell at 206-348-0789 or jriffell@uw.edu and Thornton at 206-543-4010 or joelt@uw.edu.

Wildfires burning in the West affect not only the areas burned, but the wider regions covered by smoke. Recent years have seen hazy skies and hazardous air quality become regular features of the late summer weather.

Many factors are causing Western wildfires to grow bigger and to generate larger, longer-lasting smoke plumes that can stretch across the continent. An analysis led by the 91探花 looks at the most detailed observations to date from the interiors of West Coast wildfire smoke plumes.

The multi-institutional team tracked and flew through wildfire plumes from the source to collect data on how the chemical composition of smoke changed over time. A resulting , published Nov. 2 in the Proceedings of the National Academy of the Sciences, shows that smoke forecasts may incorrectly predict the amount of particles in staler smoke.

The new results could significantly change the estimate for particles in staler smoke, which could be the difference between 鈥渕oderate鈥� and 鈥渦nhealthy鈥� air quality in regions downwind of the fire.

鈥淲ildfires are getting larger and more frequent, and smoke is becoming a more important contributor to overall air pollution,鈥� said lead author , a 91探花professor of atmospheric sciences. 鈥淲e really targeted the smoke plumes close to the source to try better understand what’s emitted and then how it can transform as it goes downwind.鈥�

Knowing how newly generated wildfire smoke transitions to stale, dissipated smoke could lead to better forecasts for air quality. Communities can use those forecasts to prepare by moving outdoor activities inside or rescheduling in cases where the air will be unsafe to be outdoors, as well as limiting other polluting activities such as wood-burning fires.

鈥淭here are two aspects that go into smoke forecasts,鈥� said first author , a 91探花postdoctoral researcher in atmospheric sciences. 鈥淥ne is just where is the smoke plume going to go, based on dynamics of how air moves in the atmosphere. But the other question is: How much smoke gets transported 鈥� how far downwind is air quality going to be bad? That鈥檚 the question our work helps to address.鈥�

When trees, grass and foliage burns at high temperatures they generate soot, or black carbon, as well as organic particles and vapors, called organic aerosols, that are more reactive than soot. Fires can also produce 鈥溾�� aerosol, a less-well-understood form of organic aerosol that gives skies a brownish haze.

Once in the air, the organic aerosols can react with oxygen or other molecules already in the atmosphere to form new chemical compounds. Air temperature, sunlight and concentration of smoke affect these reactions and thus alter the properties of the older smoke plume.

The multi-institutional team measured these reactions by flying through wildfire plumes in July and August 2018 as part of WE-CAN, or the field campaign led by Colorado State University.

Research flights from Boise, Idaho, used a C-130 aircraft to observe the smoke. The study flew through levels of 2,000 micrograms per cubic meter, or about seven times the worst air experienced in Seattle this summer. Seals on the aircraft kept the air inside the craft much cleaner, though researchers said it was like flying through campfire smoke.

鈥淲e tried to find a nice, organized plume where we could start as close to the fire as possible,鈥� Palm said. 鈥淭hen using the wind speed we would try to sample the same air on subsequent transects as it was traveling downwind.鈥�

The analysis in the new paper focused on nine well-defined smoke plumes generated by the in southwestern Oregon, the Bear Trap fire in Utah, the Goldstone fire in Montana, the South Sugarloaf fire in Nevada, and the Sharps, Kiwah, Beaver Creek and Rabbit Foot wildfires in Idaho.

鈥淵ou can’t really reproduce large wildfires in a laboratory,鈥� Palm said. 鈥淚n general, we tried to sample the smoke as it was aging to investigate the chemistry, the physical transformations that are happening.鈥�

The researchers found that one class of wildfire emissions, phenols, make up only 4% of the burned material but about one-third of the light-absorbing 鈥渂rown carbon鈥� molecules in fresh smoke. They found evidence of complex transformations within the plume: Vapors are condensing into particles, but at the same time and almost the same rate, particulate components are evaporating back into gases. The balance determines how much particulate matter survives, and thus the air quality, as the plume travels downwind.

鈥淥ne of the interesting aspects was illustrating just how dynamic the smoke is,鈥� Palm said. 鈥淲ith competing processes, previous measurements made it look like nothing was changing. But with our measurements we could really illustrate the dynamic nature of the smoke.鈥�

The researchers found that these changes to chemical composition happen faster than expected. As soon as the smoke is in the air, even as it鈥檚 moving and dissipating, it starts to evaporate and react with the surrounding gases in the atmosphere.

鈥淲hen smoke plumes are fresh, they鈥檙e almost like a low-grade extension of a fire, because there鈥檚 so much chemical activity going on in those first few hours,鈥� Thornton said.

The authors also performed a set of inside a research chamber in Boulder, Colorado, that looked at how the ingredients in smoke react in daytime and nighttime conditions. Wildfires tend to grow in the afternoon winds when sunlight speeds up chemical reactions, then die down and smolder at night. But very large wildfires can continue to blaze overnight when darker skies change the chemistry.

Understanding the composition of the smoke could also improve weather forecasts, because smoke cools the air underneath and can even change wind patterns.

鈥淚n Seattle, there are some thoughts that the smoke changed the weather,鈥� Thornton said. 鈥淭hose kinds of feedbacks with the smoke interacting with the sunlight are really interesting going forward.鈥�

The research was funded by the National Science Foundation and the National Oceanic and Atmospheric Administration. Other co-authors are graduate students and and research scientist in the 91探花Department of Atmospheric Sciences; Lauren Garofalo, Matson Pothier, Delphine Farmer, Sonia Kreidenweis and Emily Fischer at Colorado State University; Rudra Pokhrel, Yingjie Shen and Shane Murphy at the University of Wyoming; Wade Permar and Lu Hu at the University of Montana; and Teresa Campos, Samuel Hall, Kirk Ullmann, Xuan Zhang and Frank Flocke at the National Center for Atmospheric Research in Boulder, Colorado.

For more information, contact Thornton at joelt@uw.edu or Palm at bbpalm@uw.edu.

is a 91探花-wide institute connecting scholars with community partners to address environmental challenges. The institute announced awards for its 2020 on May 5.

Four research teams were chosen from 43 that applied. Proposals were reviewed by an 11-member committee including faculty and staff in several areas as well as an outside community member. This is the program’s second year.

Each team will receive up to $75,000 as well as administrative and communications support for a 16-month period ending in September 2021.

Crucially, the researchers also plan to collaborate with community partners from El Centro de la Raza locally to universities internationally for these projects. All of the community partners involved are listed on the .

Does vegetation help mitigate roadway and aircraft-related air pollution in Seattle?

, associate professor of environmental and occupational health sciences, is principal investigator on this community-engaged study using drones for 3D air quality measurements.

Co-investigators are professor and assistant professor of civil and environmental engineering, and , professor of atmospheric sciences.

According to their proposal, “Findings from this study will provide local and highly relevant evidence on the effectiveness of urban planning initiatives that may utilize greenery as an approach to address particulate air pollution.”

Hazard planning, food sovereignty and climate adaptation in the Alaskan Arctic听

, assistant professor in the Department of American Indian Studies and the School of Marine and Environmental Affairs, is this project’s principal investigator and co-director.

is a 500-person community in Northwest Alaska about 80 miles above the Arctic Circle. Sea-ice cover around this area has decreased dramatically in the last two decades, increasing coastal erosion during storms and the frequency of traveler distress calls, among other concerns.

For this research, an interdisciplinary team of 91探花polar researchers will work with area search and rescue volunteers to help Kivalina and its residents achieve more safety, resilience and food sovereignty, and become a model of community-driven polar research. The team also plans to develop new methods in sea ice forecasting to support local decision-making, among several other goals.

Other 91探花researchers involved are , chair and professor; and , research assistant professor, both in atmospheric sciences.

P铆kyav on the Mid-Klamath River: Peeshk锚esh Y谩v Um煤saheesh

The flows through parts of Oregon and Northern California. Four hydroelectric dams along the river are scheduled for removal in 2022. The , in that area, is among the largest in California.

This research team proposes a river restoration process on the Klamath that centers on Karuk tribal sovereignty using a model of justice, helping to bring tribal perspectives to large-scale governance. The title of the project, they write, translates to “the river will look good” 鈥� and the phrase “goes far below the surface to include function, connection and ceremonial renewal.”

The team plans an intergenerational, field-based school on the river, working with Karuk youth and cultural practitioners to gather historical maps, stories and spatial data on Karuk uses of floodplain ecosystems.

91探花team members for this project are , assistant professor in the School of Marine and Environmental Affairs; , a lecturer in Comparative History of Ideas and the Program on the Environment; and Karuk tribal member Kimberly Yazzie, a doctoral student in the School of Aquatic and Fishery Sciences.

Lessons from urban indigenous immigrants 听

“This project will compare a self-managed indigenous immigrant community still using traditional practices in Iquitos, Peru,” the team wrote, “to a similar indigenous immigrant community nearby that developed with social and political pressures to colonially urbanize and leave traditional practices behind.”

91探花members of the research team are , affiliate assistant professor of landscape architecture; , photographer with the 91探花Center for One Health Research; , lecturer in the 91探花Bothell School of Interdisciplinary Arts & Sciences; Kathleen Wolf, research social scientist with the School of Environment and Forest Sciences; and doctoral student of the School of Public Health.

“We use an innovative, mixed-methods approach by combining indigenous knowledge, science and art to document environmental conditions, ecosystem health, traditional knowledge practices, and human-nature connections in each community,” the team wrote.

Environmental and human health impacts of a new invasive species in Madagascar

A fifth project was in March, representing the second project funded in collaboration with the 91探花Population Health Initiative. The project’s 91探花leads are , assistant professor in the School of Aquatic and Fishery Sciences; and , professor in the Department of Environmental and Occupational Health Sciences.

For more information, contact the EarthLab Innovation Grants program lead at elgrants@uw.edu.

Regulators can now breathe easier. A 91探花-led study, published in March in the , provides a fuller picture of the relationship between nitrogen oxides 鈥� the tailpipe-generated particles at the center of the Volkswagen scandal, also known as NOx, 鈥� and PM2.5, the microscopic particles that can lodge in lungs.

Results show that declining NOx due to tighter standards does ultimately lead to cleaner air 鈥� it just might take longer.

A key finding is how the concentration of NOx affects the formation of PM2.5, found in smog, by changing the chemistry of the hydrocarbon vapors that transform into the particles less than 2.5 microns across, or about 3 percent the width of a human hair.

“We found that there are two different regimes of PM2.5 formation,” said first author , a 91探花professor of atmospheric sciences. “One where adding NOx enhances PM2.5, and one where adding NOx suppresses PM2.5.”

The findings could help explain why air quality appears to have stagnated in recent years over some parts of North America, even as emissions of all types have been dropping. Regulators are concerned because air pollution is a leading human health hazard, especially among children, the elderly and those with respiratory or heart problems.

Officials knew to expect slow progress on reducing ozone, another component of smog, because of a somewhat similar role that NO_x plays in ozone formation. But the recent concern was that PM2.5 concentrations might be different, and would just continue to go up with decreasing NOx emissions.

“We’re basically saying: ‘Hold on, don’t worry. Things might look like they’re getting worse, in some places, but overall they should get better,'” Thornton said.

The discovery of this complex relationship could also help atmospheric scientists predict how air will change as emissions drop further.

Hydrocarbon vapors 鈥� carbon-based compounds from either natural sources or fossil fuels 鈥� do not readily convert to PM2.5. Only through a set of chemical reactions in the air that involve free radicals, which are produced by sunlight and modulated by NOx, are hydrocarbon vapors converted into particulates.

The research combines observations from a 2013 that measured emissions plumes in the air above Southeastern U.S. cities as well as experiments conducted at the Pacific Northwest National Laboratory.

The ease with which hydrocarbons convert to PM2.5 shifts with the availability of the different ingredients, and the reaction rates also change. Both must be considered to understand the effect on regional PM2.5, the new study shows. Even though the process of PM2.5 formation from hydrocarbons gets easier as NO_x drops, the chemical reactions slow down. Together the two effects mean that, eventually, drops in nitrogen oxides will lead to drops in PM2.5.

“You could be in a regime where it gets worse, but if you push past it, it gets better,” Thornton said. “In most urban areas in the U.S., the NOx levels are low enough that we are past this point already.”

Previous research from Thornton’s group has shown why is more resistant to emissions regulations than summer smog: because different temperatures provide seasonal conditions that send the chemistry down distinct paths.

The research was funded by the Department of Energy, the Environmental Protection Agency and the National Science Foundation. The aircraft study was funded by the National Oceanic and Atmospheric Administration. The other lead author is at the Environmental Protection Agency, who was a visiting scientist at the 91探花. Other co-authors are from the 91探花Department of Atmospheric Sciences; Pacific Northwest National Laboratory; the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory; and the University of Colorado, Boulder.

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For more information, contact Thornton at 206-543-4010 or thornton@atmos.uw.edu.

The air in the United States is much cleaner than even a decade ago. But those improvements have come mainly in summer, the season that used to be the poster child for haze-containing particles that cause asthma, lung cancer and other illnesses.

A led by the 91探花 shows why winter air pollution levels have remained high, despite overall lower levels of harmful emissions from power plants and vehicles throughout the year.

“In the past 10 years or so, the summer air pollution levels have decreased rapidly, whereas the winter air pollution levels have not. Air quality in summer is now almost the same as in winter in the eastern U.S.,” said corresponding author , who did the work as part of his 91探花doctorate in atmospheric sciences. “We have pinpointed the chemical processes that explain the seasonal difference in response to emissions reductions.”

The study, published the week of July 23 in the Proceedings of the National Academy of Sciences, shows that the particles follow different pathways in the winter.

Results came from analyzing observations collected during the 2015 (WINTER) campaign. During that UW-led effort, researchers spent six weeks in winter flying through pollution plumes over New York City, Baltimore, Cincinnati, Columbus, Pittsburgh, Washington, D.C., and along the coal-fired power plants of the Ohio River Valley.

The study was funded by the National Science Foundation, with in-kind support from NASA and the National Oceanic and Atmospheric Administration.

Particles that form smog come in different flavors. Two important ones are sulfates, from sulfur dioxide emitted mainly by coal-fired power plants, and nitrates, created from nitrogen oxides known collectively as NOx. Air-quality regulations have lowered sulfur dioxide in the U.S. by 68 percent between 2007 and 2015, and NOx by about a third during that time.

Summertime levels of particulates 鈥� when the two flavors of oxides clump up into watery packets of nitrates and sulfates that create beautiful sunsets but harm human health 鈥� have dropped in the eastern U.S. by about a third during that time. But the winter concentrations of particulates have decreased by only half as much, for reasons that had been unclear.

“The air quality models that we use to understand the origin of air pollution perform quite well in summer, but have some issues in the wintertime. Before this study, we could not reproduce the observed particulate composition in winter,” said , who was second author on the paper and co-principal investigator of the field campaign. “We now have a better tool to look at what is the best strategy to improve wintertime air quality on regional scales in the eastern U.S., and potentially other places, like Europe and Asia.”

In the summer, some of the emitted NOx and sulfur dioxide remains in the gas phase and gets zapped by sunlight or deposited on land, and the rest forms particulates in the form of nitrates and sulfates. As the primary ingredients drop, so do the levels of particulates.

But the new analysis shows that the chemistry of wintertime air follows a more complex path. With less sunlight and colder temperatures, more of the chemistry happens in the liquid phase, on the surfaces of existing particulates or liquid and ice clouds. In that phase, as the primary ingredients drop, the efficiency of converting sulfur dioxide to sulfate rises, because more oxidants are available. And as sulfate goes down, the particulates become less acidic, making NOx convert more easily to nitrates.

So, even though air quality regulations have reduced both types of primary emissions, the total amount of particulates that harm human health has dropped more slowly.

“It’s not that the reductions aren’t working. It’s just that the reductions have a cancelling effect, and the cancelling effect has a set strength,” said Shah, who is now a postdoctoral researcher at Harvard University. “We need to make further reductions. Once the reductions become larger than the cancelling effect, then winter will start behaving more like summer.”

The study predicts that unless emissions reductions outpace current forecasts, air quality in winter will continue to improve only gradually until at least 2023. At this rate it would be several years before emissions reach levels when wintertime pollution starts to drop more quickly.

“This paper shows that understanding the underlying atmospheric chemistry that converts primary pollutants into fine particulate matter is critical for calibrating our expectations about what emissions reductions will accomplish, and therefore for how to optimize future emissions reductions to continue getting the ‘biggest bang for the buck’ in terms of reducing fine particulate matter concentrations,” said third author , who was the principal investigator on the field campaign.

The findings suggest that more emissions reductions, of both sulfur and nitrogen oxides, will be needed to improve wintertime air quality in the Eastern U.S. and other cold climates.

“This research helps explain why emissions controls to reduce air pollution substances, such as sulfate and nitrate, have not been as successful as expected in the eastern U.S. in winter,” said Sylvia Edgerton, program director in the NSF’s Division of Atmospheric and Geospace Sciences, which funded the research. “The WINTER field campaign produced a unique set of winter observations. They demonstrate that chemical feedbacks during winter months counteract expected reductions in air pollution due to reduced emissions.”

Other co-authors are and at the UW; Jason Schroder, Pedro Campuzano-Jost, and Jose Jimenez at the University of Colorado Boulder; Hongyu Guo and Rodney Weber at Georgia Institute of Technology; Amy Sullivan at Colorado State University; Jaime Green, Marc Fiddler and Solomon Bililign at North Carolina A&T State University; Teresa Campos, Meghan Stell, Andrew Weinheimer and Denise Montzka at the National Center for Atmospheric Research in Boulder; and Steven Brown at the National Oceanic and Atmospheric Administration in Boulder.

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For more information, contact Shah at 412-736-0062 听or vshah@uw.edu, Jaegle at 206-685-2679 or jaegle@uw.edu and Thornton at 206-543-4010 or joelt@uw.edu.

NSF grants: AGS-1360745, AGS-1360834, AGS-1360730. NASA: NNX15AT96G

A mapping lightning around the globe finds lightning strokes occur nearly twice as often directly above heavily-trafficked shipping lanes in the Indian Ocean and the South China Sea than they do in areas of the ocean adjacent to shipping lanes that have similar climates.

The difference in lightning activity can鈥檛 be explained by changes in the weather, according to the study鈥檚 authors, who conclude that aerosol particles emitted in ship exhaust are changing how storm clouds form over the ocean.

The study听published Sept. 7 in Geophysical Research Letters is the first to show ship exhaust can alter thunderstorm intensity. The researchers conclude that particles from ship exhaust make cloud droplets smaller, lifting them higher in the atmosphere. This creates more ice particles and leads to more lightning.

The results provide some of the first evidence that humans are changing cloud formation on a nearly continual basis, rather than after a specific incident like a wildfire, according to the authors. Cloud formation can affect rainfall patterns and alter climate by changing how much sunlight clouds reflect to space.

鈥淚t鈥檚 one of the clearest examples of how humans are actually changing the intensity of storm processes on Earth through the emission of particulates from combustion,鈥� said lead author , a 91探花professor of atmospheric sciences.

All combustion engines emit exhaust, which contains microscopic particles of soot and compounds of nitrogen and sulfur. These particles, known as aerosols, form the smog and haze typical of large cities. They also act as cloud condensation nuclei 鈥� the seeds on which clouds form. Water vapor condenses around aerosols in the atmosphere, creating droplets that make up clouds.

Cargo ships crossing oceans emit exhaust continuously and scientists can use ship exhaust to better understand how aerosols affect cloud formation.

Co-author , a former 91探花postdoctoral researcher who is now an atmospheric scientist at NASA Marshall Space Flight Center in Huntsville, Alabama, was analyzing data from the , a UW-based network of sensors that locates lightning strokes all over the globe, when she noticed a nearly straight line of lightning strokes across the Indian Ocean.

Virts and her colleagues compared the lightning location data to maps of ships鈥� exhaust plumes from a global database of ship emissions. Looking at the locations of 1.5 billion lightning strokes from 2005 to 2016, the team found nearly twice as many lightning strokes on average over major routes ships take across the northern Indian Ocean, through the Strait of Malacca and into the South China Sea, compared to adjacent areas of the ocean that have similar climates.

鈥淎ll we had to do was make a map of where the lightning was enhanced and a map of where the ships are traveling and it was pretty obvious just from the co-location of both of those that the ships were somehow involved in enhancing lightning,鈥� Thornton said.

Water molecules need aerosols to condense into clouds. Where the atmosphere has few aerosol particles 鈥� over the ocean, for instance 鈥� water molecules have fewer particles to condense around, so cloud droplets are large.

When more aerosols are added to the air, like from ship exhaust, water molecules have more particles to collect around. More cloud droplets form, but they are smaller. Being lighter, these smaller droplets travel higher into the atmosphere and more of them reach the freezing line, creating more ice, which creates more lightning. Storm clouds become electrified when ice particles collide with each other and with unfrozen droplets in the cloud. Lightning is the atmosphere鈥檚 way of neutralizing that built-up electric charge.

Ships burn dirtier fuels in the open ocean away from port, spewing more aerosols and creating even more lightning, Thornton said.

鈥淚t is the first time we have, literally, a smoking gun, showing over pristine ocean areas that the lightning amount is more than doubling,鈥� said Daniel Rosenfeld, an atmospheric scientist at the Hebrew University of Jerusalem who was not connected to the study. 鈥淭he study shows, highly unambiguously, the relationship between anthropogenic emissions 鈥� in this case, from diesel engines 鈥� on deep convective clouds.鈥�

Other co-authors are , a 91探花professor of Earth and space sciences who directs lightning network, and , a research meteorologist at the UW’s Joint Institute for the Study of the Atmosphere and Ocean.

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For more information, contact Thornton at joelt@uw.edu or 206-962-1430.

This was originally posted as a by the American Geophysical Union.

A 91探花 atmospheric scientist is leading a scientific effort to study the evolution of air particles in the eastern U.S. in the winter. The six-week is sampling emissions through mid-March from their source to farther out in the environment, at all times of day and the long winter nights.

“We hope to better understand the fate of pollutants and their impact on the global atmosphere during wintertime,” said lead investigator , a 91探花professor of atmospheric sciences.

The project is measuring pollution from New York City south to Atlanta, over the coal-fired power plants of the Ohio River Valley, and in the more temperate southeastern U.S., and looking at what happens as those pollutants are blown offshore. Measurements are from a C-130 military transport plane owned by the National Science Foundation and operated for research by the National Center for Atmospheric Research.

The team is based out of a hangar at the NASA Langley Research Center in Hampton, Virginia, through March 15.

Observations include the amount and spatial pattern of the winter emissions, the timescale for them to be converted to other molecules such as ozone, or smog, as well as small particulates 鈥� the form of pollution most hazardous to health 鈥� and how those evolve over time.

The findings will be relevant for other densely populated places.

“This is directly applicable to emissions and transport of pollutants in any region that experiences shorter days, longer nights and colder temperatures during the winter,” Thornton said.

Running the flights during winter presents some challenges.

“In winter, pollution over land often stays close to the ground,” Thornton said. To sample these layers the group is conducting “missed approach” maneuvers in which an airport gives permission for the aircraft to come close to landing, about 100 feet from the ground, and then swoop back up while collecting measurements.

Low winter clouds are also an issue.

“If clouds extend too close to the water’s surface they prevent the pilots from flying visually,” Thornton said, “and we don’t have a way to know whether the clouds are too low until we fly out to look.”

The on the plane include a machine developed by Thornton’s group that takes precise chemical measurements several times a second. 91探花graduate student and postdoctoral fellow are operating the instrument during the flights. 91探花graduate student and 91探花meteorologist analyze atmospheric forecasts to determine the best conditions to fly.

Co-principal investigator , a 91探花professor of atmospheric sciences, helped with the flight plans in the first two weeks of February and participated in two of the surveys so far. The winter storms hitting the Northeast have postponed some of the research flights, she said, but the team has planned for some inevitable weather delays.

“The short daylight hours, cold temperatures and ground snow cover lead to different types of chemical reactions in the winter atmosphere compared with summer. In particular, nighttime chemistry plays a much more important role,” Jaegl茅 said.

“We don’t have that much information about what is going on in the winter,” she added. “This will bring a wealth of information in terms of the transformation of pollutants.”

The findings can be used to help regulate emissions and predict air quality during the winter months.

These measurements will complement a recent , in which 91探花and other scientists sampled the air over the same region in June and July of 2013.

The current campaign is funded by the National Science Foundation and the National Oceanic and Atmospheric Administration, and supported by the National Center for Atmospheric Research. Other are from NOAA, the University of Colorado the University of California, Berkeley, and Georgia Institute of Technology. Other partners are the University of New Hampshire, the University of Maryland, Baltimore County and the North Carolina Agricultural and Technical State University.

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听For more information, contact Thornton at joelt@uw.edu and Jaegl茅 at 206-685-2679 or jaegle@uw.edu.

New research by German, Finnish and U.S. scientists elucidates the process by which gas wafting from coniferous trees creates particles that can reflect sunlight or promote cloud formation, both important climate feedbacks. The is published Feb. 27 in .

“In many forested regions, you can go and observe particles apparently form from thin air. They’re not emitted from anything, they just appear,” said , a 91探花 associate professor of atmospheric sciences and second author on the paper.

The study shows the chemistry behind these particles’ formation, and estimates they may be the dominant source of aerosols over boreal forests. The has named aerosols generally one of the biggest unknowns for climate change.

Scientists have known for decades that gases from pine trees can form particles that grow from just 1 nanometer in size to 100 nanometers in about a day. These airborne solid or liquid particles can reflect sunlight, and at 100 nanometers they are large enough to condense water vapor and prompt cloud formation.

In the new paper, researchers took measurements in Finnish pine forests and then simulated the same particle formation in an air chamber at Germany’s . A new type of chemical mass spectrometry let researchers pick out 1 in a trillion molecules and follow their evolution.

Results showed that when a pine-scented molecule combines with ozone in the surrounding air, some of the resulting free radicals grab oxygen with unprecedented speed.

“The radical is so desperate to become a regular molecule again that it reacts with itself. The new oxygen breaks off a hydrogen from a neighboring carbon to keep for itself, and then more oxygen comes in to where the hydrogen was broken off,” Thornton said.

Current chemistry would predict that 3 to 5 oxygen molecules could be added per day during oxidation, Thornton said. But researchers observed the free radical adding 10 to 12 oxygen molecules in a single step. This new, bigger molecule wants to be in a solid or liquid state, rather than gas, and condenses onto small particles of just 3 nanometers. Researchers found so many of these molecules are produced that they can clump together and grow to a size big enough to influence climate.

“I think unravelling that chemistry is going to have some profound impacts on how we describe atmospheric chemistry generally,” Thornton said.

Lead author did the work as a postdoctoral researcher in Germany, working in the group of co-author . Ehn is now based at the University of Helsinki in Finland.

Boreal or pine forests give off the largest amount of these compounds, so the finding is especially relevant for the northern parts of North America, Europe and Russia. Other types of forests emit similar vapors, Thornton said, and he believes the rapid oxidation may apply to a broad range of atmospheric compounds.

“I think a lot of missing puzzle pieces in atmospheric chemistry will start to fall into place once we incorporate this understanding,” Thornton said.

Forests are thought to emit exponentially more of these scented compounds as temperatures rise. Understanding how those vapors react could help to predict how forested regions will respond to global warming, and what role they will play in the planet’s response.

In related work, Thornton’s group was part of last summer to study air chemistry over the Southeastern United States, where aerosols formed by reforested areas or from pollution could help explain why that region has not warmed as much as other places.

“It’s thought that as the Earth warms there will be more of these vapors emitted, and some fraction of them will be converted to particles which can potentially shade the Earth’s surface,” Thornton said. “How effective that is at temperature regulation is still very much an open question.”

The 33 co-authors also include Felipe Lopez-Hilfiker and Ben Lee, both at the UW, and researchers from the University of Copenhagen in Denmark, the Institute for Tropospheric Research in Germany, Aerodyne Research Inc. in Massachusetts, and Tampere University of Technology in Finland.

The research was funded by the European Research Council, Academy of Finland Center of Excellence, U.S. Department of Energy, and the Emil Aaltonen Foundation.

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For more information, contact Thornton at 206-543-4010 or joelt@uw.edu and Ehn at mikael.ehn@helsinki.fi.