This past summer, if New Yorkers looked up from the hustle and bustle of urban life, they may have spotted a C-130 research aircraft flying above the skyscrapers. The plane was doing research flights over the tri-state area to collect data on urban air quality for a scientific research field campaign called the Greater New York Oxidant, Trace Gas, Halogen, and Aerosol Airborne Mission, also known as GOTHAAM. No classic villains or superheroes here, just researchers studying the composition of the air in both the light and dark of the New York metro area. 

The tri-state area — where New York, New Jersey, and Connecticut meet — is a unique urban environment as it sits at an intersection of ocean, dense forests, and urban sprawl. Even though over 60 million people live and breathe inside this complex region, how the air mixes and combines from these three areas and what the resulting air chemistry looks like is relatively understudied. The GOTHAAM team aimed not only to get a better picture of the air in and around New York City, but how pollution ebbs and flows in this urban environment throughout a 24-hour time period. 

“The air we breathe is one of those very subtle, yet very impactful things that directly affects our quality of life,” said John Mak, a professor at Stony Brook University who is leading the GOTHAAM campaign. “New Yorkers may have noticed, as I have, that you can have a clear morning, but then a couple of hours later, it’s hazy and smoggy. The data from GOTHAAM will help us better understand what is causing that and how the process occurs so quickly.”

Supporting field campaigns, like GOTHAAM, is one of the fundamental purposes of the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR). NSF NCAR provides universities, government agencies, and the private sector access to state-of-the-art resources such as research aircraft, cutting-edge instruments, and knowledgeable experts. These partnerships enable the research community to answer society’s most pressing science questions as well as train the next generation of researchers, engineers, and technicians. 

The GOTHAAM campaign was led by Stony Brook University with participants from NSF NCAR; Colorado State University; University of California, Irvine; University of Colorado; University of Michigan; University of Washington; University of Maryland; University of Wisconsin; and NASA Goddard Space Flight Center. The research was funded by the National Science Foundation.

Airborne advantage 

In a complex urban environment, air quality monitors at ground level capture a hyper-local picture of what’s going on – such as emissions from the hot dog vendor around the corner or the laundromat across the street. When researchers are able to zoom out and up they are able to capture the broader features of the city and see how emissions combine to produce an average of what the city is breathing. 

GOTHAAM utilized the NSF NCAR C-130, which houses a sophisticated flying laboratory. Using an airplane allowed researchers to take vertical profiles of the air. In order to get as much information as possible, an NSF NCAR pilot would fly the plane at both high and low altitudes. Because of the density of tall buildings in the area, the team had to get creative with how to obtain the profiles of the atmosphere closer to the ground. To do this, they would fly low over the Hudson River or do “missed” approaches at airports, where the plane almost touches down on the runway, but ascends before making contact with the ground.

A major goal of the campaign was exploring how the chemistry of the air changed over the day-night cycle. Atmospheric chemistry is sunlight driven and researchers wanted to know how chemistry evolves when the Sun goes down and what happens when the Sun rises again, initiating rapid changes. 

“There are satellites that measure air quality throughout the day that give us decent information, but at night we’re kind of blind,” said Rebecca Hornbrook, an atmospheric chemist at NSF NCAR. “Data from GOTHAAM will help us better understand the entire 24-hour period and how emissions change. What you go to bed with can be very different from what you wake up to and we want to understand that process.” 

Over the course of the 21 research flights, the team worked their way around the clock – starting with flights that took off in the morning and gradually pushing the take off time back until they had measurements from all hours of the day and night.

Accelerating answers

It takes a lot of small discoveries to fully answer complex science questions. Large-scale field campaigns, like GOTHAAM, allow researchers to pool resources and collect as much data as possible in a short period of time. The intensive work conducted over a period of weeks accelerates the path to scientific understanding.

NSF NCAR helps advance these scientific breakthroughs by providing the research community with cutting-edge modeling, observational tools, and computing resources. For GOTHAAM, a team of specialists from NSF NCAR helped the campaign run smoothly. The team was made up of pilots, technicians, project managers, scientists, software engineers, and mechanics that provided valuable expertise and kept the project on schedule. 

Experienced pilots worked with Mak, the project lead from Stony Brook, to design flights that were both feasible and met the study’s scientific objectives. The pilots then communicated with the Federal Aviation Administration (FAA) to coordinate 21 flights in one of the busiest airspaces in the world. 

“I’ve flown several field campaigns, but GOTHAAM stood out because it was flown in some pretty busy airspace,” said Edward Proulx, an NSF NCAR pilot. “Because there was a lot of traffic, it required more demanding flying, but it kept things interesting.” 

The large cargo area of the NSF NCAR C-130 is outfitted with racks where a wide assortment of observational instruments can be installed. Technicians installed over a dozen instruments such as mass spectrometers that can identify hundreds of chemical compounds, particle analyzers, and sensors that detect key oxidants like ozone. 

Installing the instruments often means figuring out safety logistics like proper ventilation and changing out parts, like power cables, to ensure devices are compatible with the aircraft platform. During the campaign, technicians and scientists monitor the instruments to ensure they are working properly. GOTHAAM experienced hot and humid conditions and the team had to adapt by using air conditioning carts to keep the hardware from overheating when the plane was parked on the tarmac and using desiccant packs to absorb excess moisture. 

“It really does require a lot of different skillsets to make a campaign successful,” said Ivana Vu, a technician at NSF NCAR. “When students tour our aviation facility, I tell them that there are over 10 different job titles here and that we come from a wide range of backgrounds. I hope it encourages them to think about how their unique interests and perspectives can contribute to this work.”  

Many of the instruments provided by the Atmospheric Chemistry Observations and Modeling Lab at NSF NCAR are highly specialized and require specific expertise to run. Several atmospheric chemists from NSF NCAR participated in GOTHAAM bringing the skills needed for running these devices as well as knowledge for analyzing the data they collected. 

“Our organization makes it so university professors don't need to know someone that can fill every role or be able to source all the specialized equipment themselves – we can provide that,” said Brett Palm, an atmospheric chemist at NSF NCAR. “Our role also isn’t just to provide really high-quality measurements, but to enhance the science by sharing our expertise. We are truly a part of the team from the initial planning to analyzing the data after the campaign is over.” 

The GOTHAAM team is just starting to dive into all the data they collected in the field, but they anticipate the dataset will help advance scientific understanding of urban air for at least a decade. Even though the campaign focused on the metropolitan New York area, much of what they learn can be translated to other urban systems around the world. As researchers, professors, and students begin to decode the observations they anticipate that they’ll also uncover connections they weren’t expecting. 

“Field campaigns are a journey of discovery,” said NSF NCAR scientist Patrick Veres. “These projects are just as much about discovering questions you didn’t think to ask when you wrote the proposal as they are about answering the questions that you started out with. I'd be surprised if the GOTHAAM dataset doesn't have a surprise or two up its sleeve.”

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