Environmental & Climate Sciences Department Seminar

Characterizing the aerosol number budget plays a crucial role in addressing the critical challenge of understanding current and projecting future climate scenarios by improving the understanding of aerosol-climate interactions. Various microphysical, dynamical, and environmental controls exert influence over atmospheric aerosols and its climate impacts. Microphysical controls, such as new particle formation (NPF), which includes the formation of new particles and their subsequent growth, impact the aerosol number size distribution, cloud condensation nuclei, air quality, and climate. Sea breeze circulations (SBC), as part of meteorological dynamical controls, transport aerosols inland, enhance vertical mixing and dispersion, and influence the spatio-temporal aerosol distribution. Additionally, different atmospheric environments exhibit diverse aerosol characteristics driven by their unique natural and anthropogenic sources, and atmospheric processes. The DOE ARM measurement campaign Tracking aerosol convection interactions experiment (TRACER), conducted from October 1, 2021, to September 30, 2022, offered a unique opportunity to study aerosol processes in Houston's distinctive urban and coastal environment. The region is characterized by isolated convection systems, frequent SBC, and emission impacts from industrial, urban, and rural areas. Additional aerosol measurements from June 1 to September 30, 2022, at a rural site exhibit a strong contrast with urban aerosol measurements at the main and other urban sites. Comprehensive observational data were analyzed, including the aerosol number size distribution, bulk aerosol chemical composition, gas-phase precursors such as SO2 and SO2-based proxies (e.g., H2SO4), and meteorology. The analysis reveals strong day-to-day variability in aerosol size distribution at all sites across the TRACER domain. The coastal regions of Houston exhibit unique characteristics in NPF frequency, seasonality, formation, and growth rates, showing a clear 'regional behavior' with an urban-rural contrast. WRF-Chem model simulations, informed by meteorological observations, were performed to gain valuable insights into the spatio-temporal factors influencing the aerosol-climate interactions in the urban-coastal region of Houston.