Harvey Mudd Chemistry Professor Participating in Nationwide Atmospheric Measurement Network

Researchers at a site in Joshua Tree National Park will measure airborne particulate matter as part of a $12 million, multi-state project. Harvey Mudd College Associate Professor of Chemistry Lelia Hawkins and her student researchers will be responsible for the new instrumental additions at this site, one of 12 such locations nationwide.

Part of the the Atmospheric SCience and mEasurement NeTwork (ASCENT), each site will be outfitted with state-of-the-art instruments for characterizing the properties of aerosols. A three-year grant from the National Science Foundation (NSF) for the project will be overseen by principal investigator Professor Nga Lee “Sally” Ng of Georgia Institute of Technology.

Aerosols impact climate by changing the Earth’s energy balance via direct absorption or scattering of solar radiation and altering the albedo (surface reflection), formation of clouds and precipitation. The Intergovernmental Panel on Climate Change assessment established that the aerosol effects represent the single largest source of uncertainty in understanding climate change.

“We are making use of existing air quality monitoring sites and, over the network of 12 stations, looking to balance remote and urban locations, unique meteorology, topography and types of pollution sources, such that our network will cover the U.S. in a representative way,” says Hawkins, who is also the Hixon Professor of Climate Studies.

In addition to the Joshua Tree location, California will have sites in Pico Rivera and Riverside. “Having these three locations within the greater Southern California area helps us capture the very different types of air quality we expect in each area and lets us study transport of pollution from one area to another,” Hawkins says. “Joshua Tree provides a remote background site with a sort of similar climate to other California sites, especially Riverside. Three sites will allow us to study Los Angeles more comprehensively.”

Joshua Tree is located in the Mojave and Colorado deserts, approximately 100 miles east of Claremont. This summer, Hawkins and her students will begin setting up and calibrating the new instruments, and then conduct data analysis on the measurements. “The staff at the site, run by the National Park Service, will be responsible for day-to-day activities once it is set up and calibrated,” she says, adding that after the three-year grant term, equipment monitoring will be handed over to another agency for the long term.

Data from ASCENT will allow researchers to address a variety of questions about how the composition and abundance of aerosols are changing, such as how the modernization of electrical production (coal to natural gas to renewable) and transportation (gasoline to electric vehicles) affect air pollution and climate-relevant variables. Hawkins plans to incorporate the data from this project into a future course at HMC.

ASCENT will be the first network of its kind in the U.S. providing detailed information about aerosol properties (Europe and China have such networks). Hawkins says one key difference between this network and existing networks is the capability to capture information in near-real time. “Usually, this work is based on filters collected over many hours or even days to weeks. But the new instruments respond on the order of minutes to hours, which means we can see how things are changing over the course of single days,” she says. “This helps us understand sources better, which helps inform policy responses. Without this information, some questions about air quality are unanswerable.”

Hawkins says she’s most excited about involving students who will study the data with her. “We’ll be able to see how our air quality changes as the U.S. changes its emissions in the coming years, with less fossil fuel combustion, more renewables and better energy efficiency to meet the energy demands of our growing population.”