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Intercomparison of Spectroscopic Measurements of Biomass Burning Aerosol Optical Properties during a Wildfire in Southern California
ESTHER MORALES, Danielle Rocco, Jaebin Ju, Jorge Gonzales, Anissa Barrera, Stephanie Salas, Daniel B. Curtis, California State University, Fullerton
Abstract Number: 241
Working Group: Wildfire Aerosols
Abstract
The optical properties of atmospheric aerosols remain one of the largest uncertainties in our understanding of Earth’s radiative balance. Wildfire events are expected to increase in size and frequency in certain areas, such as the Western United States, due to climate change and other anthropogenic activities. Therefore, it is crucial to better understand the optical properties of biomass burning aerosol.
In this study a suite of instruments was deployed indoors and outdoors at California State University, Fullerton to measure ambient aerosol particles during a nearby wildfire event in Southern California during October 26, 2020 through November 2, 2020. The instruments used were an Integrating Nephelometer (Ambilabs 2-WIN) to measure scattering coefficient at wavelengths of 450 nm and 525 nm, a Cavity Attenuated Phase Shift Spectrometer (CAPS, PMex Aerodyne, Inc.) to measure extinction coefficient at a wavelength of 450 nm, and two co-located Purple Air Sensors (one indoors and one outdoors). Absorption coefficients were calculated using an extinction minus scattering coefficient comparison. Particle aerodynamic size distributions were measured using a Scanning Mobility Particle Sizer (SMPS, TSI, Inc.) and were used to perform a Mie retrieval of the effective refractive index of the particles over time. Measurements were intercompared and compared with mass measurements from a reference monitoring station (South Coast Air Quality Management District, Anaheim-Loara) located approximately 10 km away.
All instruments were located indoors at California State University, Fullerton (CSUF) with the exception of one PurpleAir sensor that was placed outdoors at CSUF and the AQMD reference monitor. The indoor and outdoor PurpleAir sensors were compared to better understand penetration of particles into the indoor environment and potential exposure of residents to particles during a wildfire. Results of these comparisons will be discussed as well as how each instrument performed against the others.