Small Particle Growth Observations at the U.S. DOE Southern Great Plains Field Site using Ambient Air Captive Aerosol Chambers

ZIHAN ZHU, Xuanlin Du, Don Collins, University of California, Riverside

     Abstract Number: 477
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
New particle formation (NPF) and growth influences the solar radiation budget and the microphysics and properties of clouds. Conventional approaches for studying NPF typically consider one or a small number of precursor gases or rely on observations of the dynamics of ambient particles. Traditional environmental chambers offer details of the species and processes that contribute to NPF, but are often limited to a narrow range of conditions and do not generally capture the complexity and variability of the atmosphere. The two portable 2-cubic meter Captive Aerosol Growth and Evolution (CAGE) chambers are designed to expose a controlled population of particles to an environment in which the air composition, temperature, and solar intensity mirror those just outside. Here we present results from the use of the CAGE chamber system at the DOE Atmospheric Radiation Measurement (ARM) Program's Southern Great Plains (SGP) site in the fall of 2021. Both chambers were operated continuously, with monodisperse seed particles injected every several hours and then intermittently measured by a scanning mobility particle sizer (SMPS). The aerosol was sometimes exposed to high humidity or high temperature upstream of the SMPS to characterize the hygroscopicity and volatility of the condensed species. The time-dependence of the growth rate for the 3-month study is quantified. The sensitivity of particle growth to the injected seed particle composition and liquid water content and to additions of precursor gases was studied by using one chamber as a baseline or reference chamber and the other as a perturbation chamber.