SPECTROSCOPIC AND PHYSICAL PROPERTIES OF ATMOSPHERIC AEROSOL PARTICLES DURING HIGH-POLLUTION EVENTS IN SOUTHERN CALIFORNIA

High pollution events like biomass burning and fireworks are short lived but produce large amounts of atmospheric aerosol particulate matter that may affect human health and the Earth’s climate. Measuring spectroscopic properties of the particles, such as the refractive index of the particles, is important to better understand their impact on Earth’s radiative budget and to improve in situ and remote sensing studies. Measuring physical properties of the aerosol, such as the size and number of particles, and how particles transfer into the indoor environment is needed to better understand potential impacts on human health. This thesis focuses on two studies measuring ambient aerosol optical and physical properties during high-pollution events on the campus of California State University, Fullerton. The first study focused on wildfire events that occurred in Orange County, California in October of 2020 and the second study measured firework particles during July 4, 2021. The results show that ambient particle concentrations increased dramatically during the events. In addition, the particles efficiently penetrate to the indoor environment, with 76% and 68% of the biomass burning and fireworks particles entering the indoor environment, respectively. The spectroscopic properties of the particles during both events were measured at a wavelength of 450 nm and were used to retrieve the refractive indices, n and k, of the particles. In both the wildfire and fireworks events, the particles were observed to absorb light, indicating the potential to increase Earth’s temperature. A third study describing the development of a laboratory-based Cavity Enhanced Aerosol Spectrometer (CEAS) is discussed. Results show that the measured aerosol spectroscopic properties were reasonable but did not match expected values calculated from Mie theory, indicating that further work in developing the instrument is needed