ARM

Editor’s note (December 2, 2024): The story below originally published November 26, 2024. The Coast-Urban-Rural Atmospheric Gradient Experiment (CoURAGE) began official data collection December 1. See what data are now available in the ARM Data Center. 

In and around Baltimore, Maryland, scientists, technicians, and students are poised for a year of measuring an urban atmosphere

Do you want more CoURAGE?

Atmospheric scientists do, especially those that study climate and weather patterns affecting urban areas around the world.

What they have in mind is CoURAGE, the Coast-Urban-Rural Atmospheric Gradient Experiment. This yearlong field campaign in and around Baltimore, Maryland, will begin data collection December 1, 2024.

CoURAGE’s principal investigator is Pennsylvania State University professor Kenneth Davis, who oversees a team of 27 co-investigators.

The source of the campaign’s core instrumentation is the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) user facility. Instruments will measure properties of clouds, aerosols, precipitation, and solar and infrared energy at multiple sites.

Earth system models are not yet well adapted to predict climate and weather variability in cities. In part, that’s because robust, coordinated, and continuous field data in urban environments are hard to find.

CoURAGE was designed to help address this gap by taking detailed observations in and around Baltimore for a full year.

Continuous Atmospheric Data

CoURAGE and its city and regional partners will collect continuous atmospheric data from surface remote sensing instruments at four sites.

The main one, arrayed with instruments from an ARM Mobile Facility (AMF), is on the grounds of a former high school in Baltimore’s Clifton Park district. Three other sites will provide contextual city and upwind data: one urban, one rural, and one on Kent Island in Chesapeake Bay, an arm of the Atlantic Ocean.

All year, meanwhile, radiosondes launched at regular intervals will provide data on vertical dimensions of the urbanized atmosphere. ARM is also planning tethered balloon system flights during the campaign.

Research flights with non-ARM crewed aircraft will occur during CoURAGE’s two intensive operational periods, which are scheduled for winter and summer 2025.

NOAA will take part through a series of Baltimore and Washington, D.C., flights already planned for its Airborne and Remote sensing Methane and Air Pollutant Surveys (AiRMAPS).

CoURAGE-related collaborations by other research aircraft are pending, including possible contributions from NASA, the National Science Foundation, and the U.S. Naval Research Laboratory.

Scientific interest in the campaign is lively in other ways. On November 4, 2024, DOE announced a fiscal year 2025 funding opportunity through its Atmospheric System Research (ASR) program area. CoURAGE is one of the two research topics featured in the announcement. Pre-applications are due January 7, 2025.

Campaign Choreography

The CoURAGE team seeks to measure the interconnected atmospheric components at play in urban environments. They include the nature of surfaces, aerosols, atmospheric chemistry, clouds, and patterns of precipitation.

Davis is an expert on the boundary layer, the first mile or so of the atmosphere. That’s where humanity resides, weather happens, and critical exchanges of water, energy, and wind-borne momentum take place between the Earth and thin shell of clouds and gases above it.

The science and the complex array of instruments from multiple partners can be a lot to coordinate.

Davis, who studied physics and choreography as an undergraduate at Princeton University, says he is grateful for the dance experience while planning CoURAGE.

“When you are in theater and the show has to get out there, you have to drop stuff and make it happen,” he says. “Field projects are the same way. You need to focus on the job and work together.”

An Urban Proxy

CoURAGE is designed to improve model simulations of the urban atmospheric boundary layer, including its regional influences.

“This is supposed to serve all cities, not just Baltimore,” says Davis.

But why choose Baltimore for this campaign?

For one, the city, in combination with its neighboring rural and marine influences, represents atmospheric conditions that exist in many coastal urban centers in the Earth’s midlatitudes.

The open ASR funding call points to common topics of scientific interest in such areas. They include the need to better understand the impacts of city land use and sea and land breezes on regional temperatures, aerosols, clouds, precipitation, boundary-layer processes, and convective storm activity and intensity.

Cities and their surroundings influence regional climate and weather patterns in ways that models struggle to express. Satellite data suggest that urbanized areas of 50,000 people or more create downwind anomalies in precipitation that open land does not.

Cities also create their own weather, often at the scale of a square mile or less. Paved areas create heat islands that spike local temperatures. Canyon-like clusters of tall buildings alter wind patterns. Trees and other vegetation have cooling effects.

“It’s a complex environment,” says Davis. “That makes it challenging to get everything right. Interesting geographic locations like this also happen to be complex meteorologically.”

BSEC Beginnings

Davis was also attracted to Baltimore because of its human resources: a pre-existing consortium of community and university partners interested in the urban environment, from soils to atmosphere.

In 2022, DOE announced it would fund Urban Integrated Field Laboratories (UIFLs) in Baltimore and three other areas in the United States.

UIFLs reflect an increased interest among scientists in how a warming world will affect cities, as well as how future changes in weather and climate patterns will affect society.

One of the UIFLs is CoURAGE’s main partner: the Baltimore Social-Environmental Collaborative (BSEC), which Davis says made the ARM campaign possible by laying the groundwork for community engagement and relevant science questions.

BSEC’s proposal to become a UIFL was finished in June 2022 and awarded that fall.

Shortly after, in December 2022, DOE put out a call for proposals to deploy an AMF in an urban environment. It was intended to support the heightened interest of DOE’s Biological and Environmental Research program in the science of urban regions and their interactions with the climate system.

The CoURAGE proposal, motivated by the synergy of BSEC and the urban AMF call, says Davis, was finished in March 2023.

BSEC’s role is to generate “the climate science required for equitable climate action in Baltimore and beyond,” says its principal investigator, Ben Zaitchik, a Johns Hopkins University professor and CoURAGE co-investigator.

That means working with city officials and community to arrive at research questions and deploying the measurement systems needed to address those questions, he says. “CoURAGE is a powerful complement to those efforts.”

Community Weather Stations

CoURAGE co-investigator Darryn Waugh, also a professor at Johns Hopkins, set up a BSEC weather station network that began operating across Baltimore in 2023.

Some of the nearly 40 stations measure ambient weather conditions; some measure and analyze precipitation, surface water, and groundwater; and some stations measure both.

Most of the stations are at churches, schools, community gardens, and parks.

The data collected are comprehensive, says Waugh: neighborhood-scale measurements of “temperature and moisture of the air, rainfall, wind speed and direction, surface pressure, and the amount of sunlight—the kind of data needed to understand the causes and develop equitable solutions.”

Beyond the network of BSEC weather stations, only one National Weather Service station operates in Baltimore, in the Inner Harbor, he says. That is not enough to record how heat and other conditions vary across the city.

ARM’s CoURAGE measurements will provide additional detailed observations of aerosols, clouds, and atmospheric profiles to help understand the atmospheric processes driving the BSEC observations.

Baltimore experiences periodic “extreme heat, flooding, air pollution,” and more, says Zaitchik, who will serve as president-elect of the American Geophysical Union for the 2025–2026 term. “CoURAGE provides a unique suite of measurements that get at the atmospheric dynamics and chemistry behind these experiences.”

The campaign, he adds, will also “dramatically extend the kinds of science questions that BSEC is able to consider.”

Area Professionals

Davis is grateful that CoURAGE is supported by BSEC’s commitment to community-engaged research.

“BSEC scientists regularly engage city stakeholders,” he says, including professionals from the Baltimore Office of Sustainability, the Baltimore City Department of Public Works, Old Goucher Community Association, and Maryland Department of the Environment (MDE).

An existing long-term observatory operated in Beltsville, Maryland, by MDE and Howard University will also supply CoURAGE data.

“CoURAGE will give MDE a better understanding of the three-dimensional feedback between the complex topography of the land-water-urban landscape and air quality,” said MDE air quality expert Joel Dreessen, “and how pollution and meteorology at the microscale result in intense gradients in air pollution, which can impact exposure and federal standard attainment in our region.”

Bringing in the Students

Most of all, CoURAGE is honey to busy-bee university students interested in science careers, including people from underrepresented groups.

Students from Morgan State and Howard—both historically Black universities—are involved in the campaign, as well as students from Johns Hopkins and Penn State.

“CoURAGE is a great opportunity for Morgan State University students to participate, observe, and be inspired by a scientific operation with real-world impacts,” says Xiaowen Li, who leads the university’s climate studies program. She is also the lead scientist working to support ARM’s core site in Clifton Park, which is owned by Morgan State.

Li’s students will launch year-round weather balloons to contribute data to the campaign.

During CoURAGE, she says, “Campaign site visits will be part of our teaching in earth science-related courses”—so students can “develop exciting projects” that use live ARM data.

Morgan State students will also do outreach for CoURAGE. For example, two undergraduates will coordinate and conduct site visits for local communities and K-12 students.

“Finally,” says Li, “there are initiatives to involve students from (Morgan State’s) School of Global Journalism and Communication,” who will report on CoURAGE and climate.

‘An Exciting Time’

Imagine, too, the thrill of CoURAGE for Jason Horne, a PhD student working with Davis at Penn State.

“As a young academic, being affiliated with a campaign of this magnitude is invaluable for research and networking,” he says.

During CoURAGE, Horne will travel the few hours from school to Baltimore “as much as possible,” he says. “Being there in person is critical for understanding how operations look on the ground and engaging with community members.”

Horne also represents another important feature of CoURAGE: its monthly virtual science meetings, which bring together dozens of researchers across the country—many of them early in their careers—for updates and discussions.

Out of those meetings came an initiative that Horne helps guide: an urban modeling group “to advance the science of land-atmosphere interactions in the urban environment,” he says. “Conversations about modeling the urban environment are essential, and many people are working on the topic. Still, there are not many collaborations of this scale within the states. CoURAGE and (the UIFLs) mark a big first step.”

In the future, Horne wants to expand the conversation beyond the Baltimore campaign, domestically and internationally, and perhaps work toward a model intercomparison project and new proposals.

“Overall,” says Horne, “being a young academic in urban research is an exciting time.”

All it took was CoURAGE.

From the states of Washington, Texas, and Michigan, scientists tell tales of ARM data

Early Career Research Program awards from the U.S. Department of Energy (DOE), announced every summer, support outstanding national laboratory and university scientists beginning their careers. The money, time, and recognition they receive accelerates formative investigations that may guide the rest of their research lives.

Since starting in 2010, the program has granted 961 awards to fund projects up to five years in duration.

Let’s take a quick look at four early career projects that began in fiscal year 2019 and employed data from DOE’s Atmospheric Radiation Measurement (ARM) user facility.

All four awardees represent varieties of expertise in aerosols, the tiny particles suspended in the atmosphere that make clouds and precipitation possible.

And all four had to cope with the travel and time restrictions rising out of the COVID-19 pandemic, which was officially declared in March 2020.

While some of their projects are still in progress, all four are getting ready to present related research—or have their research presented—at the 2024 American Geophysical Union (AGU) Annual Meeting in Washington, D.C., and the 2025 American Meteorological Society (AMS) Annual Meeting in New Orleans, Louisiana.

Susannah Burrows, Earth Scientist, Pacific Northwest National Laboratory (PNNL)

Burrows devoted her Early Career Award to investigating the sources, chemistry, and physical properties of ice-nucleating particles (INPs).

INPs contribute to the formation of ice in mixed-phase clouds (those containing both water and ice) by acting as a matrix for water droplets to freeze upon. They are 10,000 times rarer in the atmosphere than other particles and commonly originate from mineral dusts and sea spray aerosols.

Burrows’ work looked at INPs from both land and sea.

To examine INPs from land, in the fall of 2021, Burrows deployed a team for a month to ARM’s Southern Great Plains (SGP) atmospheric observatory in Oklahoma to collect data as part of her first ARM field campaign, Agricultural Ice Nuclei at SGP (AGINSGP).

Burrows also directed research on how sea spray aerosols contribute to INP formation. Her team looked at how much organic particulate matter at the ocean surface transfers to sea spray and, in turn, how many INPs are transferred from the ocean to the atmosphere.

On land or at sea, the focus is on “immersion mode” INPs, which when fully immersed in a cloud droplet activate ice formation at relatively warm temperatures, as low as minus 15 C (5 F). Without an INP, pure water droplets do not freeze until about minus 36 C (minus 32.8 F) or colder.

On April 11, 2022, AGINSGP’s most productive day, the Burrows team collected 150 INPs, “the largest number collected in a single day” during a field experiment, she says.

A June 2024 paper led by PNNL earth scientist Gavin Cornwell used AGINSGP data to report for the first time that particles were more likely to be active as INPs if they contain organic matter, particularly phosphates, as well as lead (previously reported) and mixed soil-organic particles.

Burrows speculates that, on land, mineral dusts with phosphate markers are associated with microbial biological activity in soils: for instance, fragments of bacterial cell walls, fungal spores, particles ejected into the atmosphere from soil or leaf surfaces by splashing raindrops, or from wind erosion of soils.

“We would like to trace such particles back to their sources,” says Burrows.

Those sources will be one focus of Cornwell’s 2024 DOE Early Career Award, she says, “which will allow him to take the next step on some of the (AGINSGP) research questions.”

For the ocean portion of her research, Burrows co-authored a January 2022 study led by former PNNL postdoctoral researcher Isabelle Steinke. It introduces a numerical framework for estimating concentrations of INPs linked to organic matter at the ocean surface. The paper identified steps in the sea spray-to-INP process that contribute uncertainty in models.

“We know there is a connection between ocean biology and particle emissions,” she says. “But we have not yet been able to get a really good process model.”

In the future, Burrows says she aims to explore “ice processes in clouds more broadly.”

In October 2023, she co-chaired a workshop with international researchers on processes of ice formation and the evolution of ice in clouds. It’s a challenging subject, says Burrows. “There are a lot of open questions.”

Burrows’ research at AGU 2024: “Characterization of springtime sources and variability of ice-nucleating particles in the agricultural region of the U.S. central Great Plains” (poster), Wednesday, December 11, 8:30 a.m. to 12:20 p.m. Eastern, Hall B-C (Poster Hall), Walter E. Washington Convention Center.

Naruki Hiranuma, Aerosol Scientist, West Texas A&M University

Hiranuma, an expert in advanced aerosol measurement techniques, devoted the bulk of his Early Career Award work to field-testing a mobile and remotely operable device that counts the abundance of INPs in ambient air. About the size of a standard household refrigerator, the Portable Ice Nucleation Experiment (PINE) cloud chamber is a miniaturized version of a chamber operating at a laboratory in Germany.

INPs, which are hard to capture and measure, represent “one of the largest uncertainties in researching aerosol-cloud-climate interactions,” he says. They influence the life span and reflectivity of clouds containing ice.

Knowing more about regional variations of INPs around the world will help reduce predictive errors in present models of cloud-climate interactions. That is especially important because the “arctic amplification” of temperatures in a warming world is marked by an increase of INPs.

Hiranuma envisions a global network of robust, semi-autonomous PINE chambers for long-term INP measurements. PINE requires only a plug-in power source and an internet connection.

Because PINE is so easy to operate and monitor remotely, “it has opened new doors for new people to come into this research community,” says Hiranuma. He worked with two postdoctoral researchers and two master’s-level students. So far, three have published peer-reviewed papers. One published in May 2024 reported on a new Python toolkit for processing INP data.

There are only two PINE devices in the United States to date, with a third expected by late 2025. Hiranuma has an ongoing PINE data analysis collaboration with the pan-European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS), an ARM collaborator. It combines INP data around the world from ARM and ACTRIS sites.

During his Early Career Award work, Hiranuma executed the world’s first PINE field measurements, recorded its limitations (including measurable temperature ranges), and verified its readiness for the rigors of remote deployments in arctic, continental, and marine environments.

For 45 days in 2019, Hiranuma oversaw PINE field operations at the first of three ARM locations: the SGP. He says the deployment in Oklahoma was “the last sanity check before we went into really remote locations.”

In 2020, Hiranuma deployed PINE at ARM’s Eastern North Atlantic (ENA) observatory in the Azores, west of mainland Portugal. The six-month deployment during the pandemic, when travel restrictions were in place, demonstrated the device’s “extreme remote controllability,” he says.

Then, after a COVID-related delay, Hiranuma shipped PINE to Utqiaġvik (formerly Barrow), Alaska. It operated for two and a half years near ARM’s North Slope of Alaska (NSA) observatory, in what he calls his project’s “most challenging environment.”

The PINE chamber is back in Texas now, ready for U.S. field missions whose funding is pending. Hiranuma is focused on publishing the last few papers from his Early Career Award project.

Hiranuma is also thinking about next steps. Those include developing an airborne application for PINE as well as a PINE chamber capable of characterizing the physical and chemical properties of INPs.

The DOE project gave him valuable lessons in project and time management, he says, but also “so many new ideas.”

Hiranuma’s research at AMS 2025: “Multi-Seasonal Measurements of the Ground-Level Atmospheric Ice-Nucleating Particle Abundance in the North Slope of Alaska” (poster), Tuesday, January 14, 3 to 4:30 p.m. Central, Hall C, New Orleans Ernest N. Morial Convention Center.

Kerri Pratt, Atmospheric Chemist, University of Michigan

In November and December 2018, just months after the Early Career Awards were announced, Pratt made a quick start on her research.

She and her team deployed instruments to the NSA to identify the sources and chemical composition of wintertime aerosols for her Arctic Aerosol Sources and Mixing States (ARCAEROMIX) campaign.

The signature piece of equipment deployed for the ARM campaign was a single-particle mass spectrometer used to measure the composition of individual aerosol particles in real time.

Pratt’s fast start on the Early Career Award also included Aerosols in the Polar Utqiaġvik Night (APUN), a 2018 investigation of aerosol measurements at the beginning of polar night, when such measurements are historically rare. Key to APUN was a delayed ice freeze-up in the Arctic Ocean near the NSA, where Pratt and her team observed breaking waves at the shore.

When open water exists at an unusual time, “you have a source of sea spray aerosol that is highly uncharacterized,” she says.

Pratt continued her focus on the understudied arctic winter during the 2019–2020 Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in the central Arctic. She deployed a sampler to collect particles that are still being analyzed one by one at the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science user facility located on the PNNL campus.

In addition to studying sea spray aerosol, her group is investigating the speculation that sea salt aerosols are also produced by blowing snow or by snow sublimation—the process in which snow passes directly from a solid to a gas, bypassing the liquid state.

In the face of delays during this “highly COVID-impacted project,” says Pratt, “we went back to data collected during a prior ARM field campaign.”

The Summertime Aerosol across the North Slope of Alaska (SAANSA) campaign, led by Pratt, took place in 2015 and 2016 at the NSA and what was then an ARM site at Oliktok Point, Alaska, adjacent to the Prudhoe Bay oil fields. Pratt pointed to three related papers funded in part by her Early Career Award:

• A June 2021 study found that droplets from frequent fog events reacted with oil-field emissions to form an SOA “that had never been documented in the Arctic,” says Pratt.
• A March 2022 paper reported on what she called “the surprising observation” during arctic summer of solid-phase particles linked to new particle formation from open-water marine biogenic sources. This is more relevant than ever in a warming Arctic, where sea ice is declining and open water increasing.
• A July 2024 paper reported “the first measurement-based quantification of aerosol mixing state in the Arctic,” says Pratt. (Mixing state is a measure of how chemical species are distributed across a population of aerosols.) The heterogeneous aerosol population in the oil-field atmosphere she studied counters the view that the Arctic has only homogeneous aerosol populations.

“There is growing attention to local arctic pollution sources,” says Pratt. “They are usually not studied. But with growing development in the Arctic, this is really important.”

Pratt’s research at AGU 2024: “Revealing the Chemical Composition of Sea Spray Aerosols over the Central Arctic Ocean during the Year-Long MOSAiC Expedition” (poster presented by Pratt’s PhD student Tiantian Zhu), Thursday, December 12, 1:40 p.m. to 5:30 p.m. Eastern, Hall B-C (Poster Hall), Walter E. Washington Convention Center.

Manish Shrivastava, Earth Scientist, PNNL

Shrivastava set out to study secondary organic aerosols (SOAs).

SOAs are “secondary” because they are not directly emitted. Instead, they begin their life cycles in the gas phase; some go on to become particles in the “large chemical reactor” of the atmosphere, he says. From there, SOAs have far-reaching impacts on the climate.

For one, they account for most of the millions of particles in atmospheric haze, a common phenomenon that affects how much of the sun’s energy reaches the Earth’s surface. SOAs can also seed cloud formation.

Shrivastava focused on the interaction between SOAs and clouds. It’s a challenging task, complicated by the thousands of organic species involved in millions of dynamic atmospheric reactions, which occur both in the gas and aerosol phases.

Of special interest were SOA reactions with water in aerosols and cloud droplets, “the big missing pieces of the puzzle,” says Shrivastava. “We do not know what (these reactions) are doing to the climate and earth systems.”

He calls the SOA-cloud aqueous puzzle “too big to be solved in five years, but we have made a lot of progress.”

Since getting the Early Career Award, Shrivastava has stacked up around 55 publications and given more than 20 invited talks at universities and conferences.

One of his most recent papers, published in Cell in June 2024, used aircraft data over the Amazon to show new particle formation in biomass burning smoke that had previously been thought unlikely: ultrafine particles generated in the smoke from vegetation fires that modify both weather and climate by making shallow clouds deeper and precipitation heavier.

Ultrafine particles are less than 50 nanometers wide, or 2,000 times thinner than a sheet of paper.

In a February 2024 paper, Shrivastava and his team developed new measurement-based modeling approaches to simulate chemical processes that govern the reactions of biomass burning organic gases in clouds that form aqueous SOAs.

ARM data from the Amazon figured into a January 2022 paper reporting the importance of previously unrecognized soil and leaf chemistry pathways for production of SOAs and other atmospheric aerosols.

Shrivastava also made forays into machine learning. In an April 2022 paper, he and his team applied supervised machine learning techniques that facilitated and sped up an online analysis of aircraft aerosol mass spectrometer data to determine the sources of organic aerosols.

In addition, he co-wrote a March 2023 paper about embedding a physics-based deep learning neural network model within a detailed regional chemical transport model. This approach sped up calculations of SOA aqueous chemistry by the regional model.

Such machine learning applications, he says, can replace computationally expensive aerosol chemistry modules within current climate models, including those simulating chemical transport.

In a May 2024 study, Shrivastava and his team applied advanced mathematical causal analyses to identify key features affecting the formation of aqueous SOA from time-series data. They demonstrated that in certain applications, such mathematical approaches may surpass traditional machine learning techniques.

However, Shrivastava insists on the critical role of thoughtfully designed measurements in closing knowledge gaps in atmospheric processes. When integrated with models, he says, the right observational data provide the most valuable insights.

He tapped data from ARM field campaigns in the Amazon and at the SGP, as well as from laboratory experiments at EMSL.

In an October 2024 paper, Shrivastava and his team discovered the critical role of acid-base reactions in the formation of molecular clusters and their growth by extremely low volatility organic gases. Such atmospheric chemistry processes help explain measurements of newly formed particles at the SGP. The study also provides insights about the role of clouds in suppressing atmospheric chemistry that otherwise causes ultrafine particles to form.

In the same paper, Shrivastava conducted preliminary simulations of SOAs around ARM’s new Bankhead National Forest observatory in Alabama. The simulations showed that new particle formation in the forest might be limited by the availability of sulfuric acid gases.

“In all, it went really well,” he says of the Early Career Award work. “We achieved much more than we envisioned.”

Shrivastava’s research at AGU 2024: “Intense formation of ultrafine particles from Amazonian vegetation fires and their invigoration of deep clouds and precipitation” (poster), Wednesday, December 11, 8:30 a.m. to 12:20 p.m. Eastern, Hall B-C (Poster Hall), Walter E. Washington Convention Center.