Atmospheric Radiation Measurement Climate Research Facility US Department of Energy



TRACER-Ultrafine aerosol Formation & Impacts (UFI)

1 July 2022 - 31 August 2022

Lead Scientist: James Smith

Observatory: amf

This project combines a unique suite of instruments and facilities for understanding the chemical species and mechanisms responsible for the formation of ultrafine particles in the Houston atmosphere during the TRACER intensive operational period (IOP). Our approach will combine direct measurements of low‑volatility precursors and size-resolved ultrafine (sub-100-nm diameter) particles together with measurements of gas-particle partitioning of ambient vapors onto size-selected nanoparticles of known composition, the latter using the UCR Captive Aerosol Growth and Evolution (CAGE) chamber.

Specifically, we will perform measurements of ambient gas and size-resolved ultrafine particle composition, as well as climatologically important particle hygroscopicity under sub- and supersaturated water vapor conditions during the TRACER IOP. Leveraging other relevant observations, including spatially and temporally resolved convective transport, we will seek to understand the dominant species that participate in new particle formation and their potential impacts on clouds and climate. Concurrently, we will measure size-resolved growth of particles of known initial size and composition using the CAGE chamber. We will use these measurements to build a process-level model that describes new particle formation in the Houston atmosphere that we hope can be linked to regional and global models through collaborations with the DOE modeling community.


Don Collins
Jeffrey Pierce


  • Parent Campaign
  • Sibling Campaign