Dr. Coty Jen,  Associate Professor
Department of Chemical Engineering
Carnegie Mellon University

Leveraging Atmospheric Nucleation to Study Atmospheric New Particle Formation

Abstract: Clouds influence climate and cool the planet by reflecting incoming sunlight away from Earth’s surface. The extent and brightness of these clouds depend on the composition and concentration of atmospheric particles, which serve as the starting point for cloud droplet formation. The majority of atmospheric particles originate from a process known as nucleation, whereby gaseous precursors react to form stable clusters (~1 nm in diameter). Sulfuric acid reacts with numerous other compounds to form new particles in the atmosphere. These nucleation precursor gases exist in trace concentrations and are emitted from various anthropogenic and biogenic sources. Emissions of these compounds are rapidly evolving as the climate changes and human activities shift. Consequently, the extent to which freshly formed particles influence Earth’s radiative balance is changing in ways that current climate models do not capture. The challenge in predicting atmospheric new particle formation over time is primarily due to the limitations of instrumentation in measuring the physicochemical properties of freshly formed particles and gases, which vary worldwide over short temporal and spatial scales. The Jen Group combines instrumentation development, field and laboratory observations, and model improvements to investigate the chemical reactions and processes that form particles in the atmosphere. This presentation has the option to cover topics including (1) a nucleation potential model to capture how complex mixtures enhance sulfuric acid nucleation rates, (2) a cheap and compact sulfuric dimethylamine-reactive condensation particle counter (SAD-RCPC) to measure trace sulfuric acid, (3) sensitive and fast time resolution measurements of new particle formation, and (4) marine and freshwater sources of precursors gases, and (5) nighttime formation of sulfuric acid in Pittsburgh, PA. 

Bio: Dr. Coty Jen is an associate professor of Chemical Engineering and a member of the Center for Atmospheric Particle Studies. Her research focuses on understanding how climate change alters new particle formation processes in polluted and remote areas. Specifically, her group specializes in developing novel aerosol measurement techniques to measure the physical characteristics and molecular makeup of atmospheric particles from several molecules to 2.5 µm in diameter produced from wildfires, human-produced pollution, and marine biological activities. 

Dr. Jen obtained her B.S. in Chemical Engineering at Columbia University (2010), M.S. in Chemical Engineering at the University of Minnesota- Twin Cities (2013), Ph.D. in Mechanical Engineering at the University of Minnesota- Twin Cities (2015), and postdoc in Environmental Science, Policy, and Management at the University of California, Berkeley (2018). She received the NSF AGS Postdoctoral Fellowship, the American Association of Aerosol Research Friedlander Award and Whitby Early Career Award,  Dean’s Early Career Fellowship, and Kun Li Teaching Award. Her research is currently funded by NSF AGS Atmospheric Chemistry and DOE Atmospheric System Research.