Aerosol Concentration, Size Distribution, and Cloud Condensation Nuclei Activity at 5 Sites in Houston during the TRACER-MAP Campaign

ZIHAN ZHU, Don Collins, Chun-Ying Chao, Robert Griffin, Kimberly Sauceda, Sascha Usenko, Rebecca J. Sheesley, Subin Yoon, James Flynn, University of California, Riverside

     Abstract Number: 555
     Working Group: Urban Aerosols

Abstract
The Tracking Aerosol Convection Interactions Experiment - Mapping of Aerosol Processes (TRACER-MAP) was carried out in the summer of 2022 as part of the larger DOE TRACER campaign. The objective of TRACER-MAP was to characterize gas concentrations and aerosol concentrations and properties across the Houston Metropolitan area. This was accomplished through measurement of a range of aerosol, gas, and meteorological parameters at five different sites that were selected to encompass the diversity of atmospheric conditions and local and transported emissions throughout the urban and suburban area. The Baylor University/University of Houston Mobile Air Quality Laboratory-2 (MAQL2) was deployed at each site for 5-7 days to gather data on aerosol size distributions, cloud condensation nuclei (CCN) activity, aerosol optical properties, aerosol composition, trace gas concentrations, and meteorological parameters. The focus of this presentation is on the aerosol size distributions measured with a scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) and the CCN activity measured with a CCN counter operated downstream of the SMPS. The gathered data were analyzed to explore the impact of meteorological conditions on new particle formation (NPF) and growth, as well as to investigate the spatial variability of these phenomena. We observed high particle number concentrations and active NPF events at locations influenced by biogenic, industrial, and urban sources. The connection between convective rain events and particle formation, growth, and size distribution will be highlighted. The concentration of supermicron particles observed at our measurement sites was found to be correlated with that measured with another APS at the main TRACER site in La Porte, TX, which in part reflects the regional scale of large dust events. The average and diel profile of CCN activity varied amongst the sites.