Particle-Resolved Modeling: A Bridge Between Scales in Aerosol Science

Prof. Nicole Riemer

University of Illinois at Urbana-Champaign

Monday December 2, 2024, 2 PM ET

Abstract:

Atmospheric aerosols are complex mixtures of chemical species, with individual particles exhibiting diverse shapes and morphologies. This “aerosol state” evolves continuously in the atmosphere. Despite significant advances in measurement techniques and process-level understanding, aerosols and their interactions with clouds remain among the largest sources of uncertainty in global climate predictions. A key challenge lies in the multiscale nature of the problem: micro-scale processes drive macro-scale impacts, complicating efforts to accurately model these dynamics. In this presentation, I will demonstrate how particle-resolved modeling addresses critical gaps in aerosol modeling. This approach simulates atmospheric aerosols as individual computational particles, tracking changes in size and composition as they undergo atmospheric transformations. Unlike traditional methods, it avoids assumptions about particle composition, enabling a detailed representation of aerosol mixing state evolution. I will highlight how this approach moves beyond simplistic definitions of “externally” or “internally” mixed populations, offering insights into spatio-temporal changes in aerosol properties. Additionally, I will show how oversimplifying aerosol diversity can lead to errors in predicting key climate-relevant properties, such as cloud condensation nuclei concentrations and aerosol optical properties. Finally, I will discuss the measurement challenges in constraining particle-resolved models, emphasizing their potential to deliver more accurate climate predictions by “getting the right answer for the right reasons.”

Biosketch:

Nicole Riemer is a Professor at the Department of Atmospheric Sciences and an Affiliate of the Department of Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign. She received her Doctorate degree in Meteorology from the University of Karlsruhe, Germany. Her research focus is the development of computer simulations that describe how aerosol particles are created, transported, and transformed in the atmosphere. Her group uses these simulations, together with observational data, to understand how aerosol particles impact human health, weather, and climate. Nicole Riemer received the NSF CAREER award, the College of Liberal Arts & Sciences Dean’s Award for Excellence in Undergraduate Teaching, and the AGU Ascent award. She is the co-chair of the Aerosol Processes Working Group of the Department of Energy Atmospheric System Research program, and editor for Journal of Geophysical Research.