Constraining Aerosol Size Distribution in the Aircraft Wake for Quantitative Stratospheric Aerosol Injection

Accelerating global warming has prompted urgent but controversial discussions about stratospheric aerosol injection (SAI), a climate intervention that involves dispersing aerosols or their precursor gases into the stratosphere to scatter incoming sunlight and cool the Earth. However, SAI’s conceptual appeal is undermined by large uncertainties about its environmental risks. These uncertainties will persist until we achieve a process-level understanding of aerosol formation and evolution, particularly under near-field conditions, where nonlinear chemistry, microphysics and wake dynamics collectively determine aerosol composition and size distribution. Deploying SAI without this knowledge is no different than performing surgery blindfolded. To bridge this critical knowledge gap, our research will constrain aerosol size distribution in the near-field aircraft wake by resolving key chemical and microphysical processes for potentially benign SAI materials, including (a) solid aerosols (e.g., calcite and diamond) and (b) aerosols formed from acid-base and oxidized organic precursor gases. We will achieve this by integrating laboratory experiments that constrain aerosol chemical mechanisms and microphysical process rates, with a coupled fluid dynamics-aerosol microphysics model that systematically scan the relevant environmental and dynamical conditions. Our goal is to develop accurate aerosol process parameterizations for integration into a model hierarchy, which will allow quantitative assessments of SAI efficacy and environmental risks, ultimately providing a scientific basis for informed climate policymaking.

Mingyi Wang is an assistant professor in the Department of the Geophysical Sciences at the University of Chicago. His research focuses on aerosol particle formation and its impact on air quality and climate change, providing novel approaches to (a) constrain the oxidative chemistry of emerging pollutants, (b) resolve aerosol microphysical processes, and (c) develop aerosol dynamics models with experimental and meteorological inputs. Before joining the University of Chicago, he was a Schmidt Science Fellow at the California Institute of Technology, where he worked on aerosol microphysics in the upper atmosphere using aircraft measurements. He received his Ph.D. from Carnegie Mellon University, where he studied the chemical mechanisms that drive particle formation in various environments. His research was recognized with the Sheldon K. Friedlander Award from the American Association for Aerosol Research.

Phillip J. Ansell obtained his Ph.D. in 2013 from the University of Illinois Urbana-Champaign in aerospace engineering. Currently, he is an associate professor of aerospace engineering at the University of Illinois Urbana-Champaign, where he serves as director of the Center for Sustainable Aviation. Ansell’s research activities include studies of aircraft design and applied aerodynamics, as well as life cycle and technoeconomic analysis of renewable energy systems for aviation. He is an associate fellow of the American Institute of Aeronautics and Astronautics, where he also serves as chair of the AIAA Sustainability Integration and Outreach Committee.

Neil M. Donahue is the Thomas Lord University Professor of Chemistry in the departments of Chemical Engineering, Chemistry, and Engineering & Public Policy at Carnegie Mellon University. He received his Ph.D. in meteorology from MIT. His research addresses the kinetics and mechanisms of atmospheric oxidation, including the effect of product volatility on the formation and growth of atmospheric particles. He developed the volatility basis set to treat the thermodynamic partitioning of complex organic mixtures in atmospheric particles as well as the dynamics of particle formation and growth. He is a fellow of the American Geophysical Union and the American Association for Aerosol Research.

David Keith has worked near the interface between climate science, energy technology, and public policy since 1990. He took first in Canada’s national physics prize exam, won MIT’s prize for excellence in experimental physics, and was one of TIME magazine’s Heroes of the Environment. Keith is professor of geophysical sciences and founding faculty director of the Climate Systems Engineering initiative at the University of Chicago. Best known for his work on the science, technology, and public policy of solar geoengineering, Keith led the development of Harvard’s Solar Geoengineering Research Program before moving to Chicago in 2023. His policy work has ranged from analysis of electricity markets and carbon prices to research on public and expert perceptions of risky technologies. Keith’s hardware work includes the first interferometer for atoms, a high-accuracy infrared spectrometer for NASA’s ER-2, the development of Carbon Engineering’s air contactor, and the development of a stratospheric propelled balloon experiment for solar geoengineering. Keith founded Carbon Engineering, a Canadian company developing technology to capture CO2 from ambient air.

Hongwei Sun earned his Ph.D. in environmental sciences from Harvard University in 2023. Following a postdoctoral appointment at the University of Washington, he joined the University of Hawaii at Manoa as an assistant professor in 2025. He is focusing on developing and applying different types of numerical models to study multiscale atmospheric processes. His primary research interests include: (1) large-scale stratospheric transport, dynamics, and aerosol processes, (2) small-scale aerosol–cloud interactions within the marine boundary layer, and (3) the application of (1) and (2) to climate intervention (geoengineering).