EC-04. Chemical and Meteorological Controls on New Particle Formation in the Southern Great Plains

Abstract
New particle formation (NPF) is estimated to account for 40 – 70 % of cloud condensation nuclei and therefore plays a central role in our understanding of aerosol-cloud interactions. It is well established that the likelihood of NPF is influenced by both chemical precursors, such as sulfuric acid, ammonia, amines, and organic compounds, as well as physical atmospheric conditions. However, the complexity of the process leads to large uncertainties in the representation of NPF in models. A complete understanding of the conditions that lead to NPF requires observations of both gas-phase chemistry as well as physical and meteorological conditions. Additionally, these measurements must be made in diverse ecosystems as both chemical and physical conditions vary by region. We investigated NPF in agricultural regions, which have been understudied compared to urban and forested regions. To do so, we deployed an atmospheric-pressure interface time-of-flight mass spectrometer (APi-TOF) and a chemical ionization time-of-flight mass spectrometer with ethanol reagent ion (EtOH-CIMS) to the US Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site in rural Oklahoma in October 2021 and Spring 2022. These mass spectrometry measurements of gas-phase compounds along with the long-term meteorological measurements from the ARM SGP site allow us to further investigate the chemical and physical conditions that contribute to NPF. I will present a case study of a few of the observed NPF events during our spring observing period. Changes in transported gases and atmospheric conditions cause differences in new particle formation and growth over the course of a few days at the same location.