EGU25-12700, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-12700
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Towards Measuring the Uptake of HCl to Organic Aerosol Proxies Under Stratospheric Conditions
Corey Pedersen1, David Verbart2, and Frank Keutsch1,2,3
Corey Pedersen et al.
  • 1School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
  • 2Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
  • 3Department of Earth and Planetary Sciences, Harvard University, Cambridge, United States

Stratospheric aerosols have long been known to directly impact ozone concentrations through heterogeneous chemistry involving halogen and nitrogen oxide species. While these aerosols are commonly assumed to consist entirely of sulfate, measurements have revealed a significant organic fraction in the ambient lower stratosphere. Additionally, wildfires like the 2019-2020 Australian wildfires have injected large quantities of organic aerosol (OA) and gas-phase organics into the stratosphere. Satellite observations following the Australian wildfires found that chlorine species were markedly perturbed, and ozone loss had occurred. These perturbations cannot be explained based on the heterogeneous chemistry of sulfate aerosol, demonstrating the need for an improved understanding of stratospheric aerosol heterogeneous chemistry. Despite the widespread presence of OA in the stratosphere, virtually no laboratory experiments have been performed to constrain the interaction of OA with halogen and nitrogen oxide species under stratospheric conditions. The uptake of HCl to OA is particularly important because it is a possible loss pathway of Cly and a precursor to the chlorine activation reaction of ClONO2 + HCl. Here I present the development of an aerosol flow reactor to study the uptake of HCl to OA proxies to improve our understanding of stratospheric chlorine and, by extension, ozone chemistry.

How to cite: Pedersen, C., Verbart, D., and Keutsch, F.: Towards Measuring the Uptake of HCl to Organic Aerosol Proxies Under Stratospheric Conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12700, https://doi.org/10.5194/egusphere-egu25-12700, 2025.