| Summary: | Atmospheric aerosols have significant impacts on air quality, climate, and human health, yet analytical and logistical challenges have limited our ability to measure these aerosol particles, particularly in remote regions. In this dissertation, individual atmospheric particles were chemically characterized in rural northern Michigan and remote northern Alaska for the first time. To enable this measurements, Chapter 2 details the construction and characterization of an updated aircraft-capable aerosol time-of-flight mass spectrometer (A-ATOFMS), capable of measuring size-resolved chemical composition of 0.07 – 1.6 µm individual particles up to 40 Hz with lower mass (~25 kg saved) and power (~600 W saved) consumption than the previous A-ATOFMS. Chapter 3 discusses size-resolved chemical composition of atmospheric aerosols in northern Michigan while the site was influenced by Canadian wildfire, urban, and local forest air masses. Throughout the study, long-range transported biomass burning aerosols were the cores of particles primarily consisting, by mass, of secondary organic aerosol from the oxidation of volatile organic compounds emitted from both wildfires and forests. In Chapter 4, we identified 14 periods of ultrafine particle growth at the same field site. Urban air mass influence during the daytime led to the highest observed growth rates, likely due to increased atmospheric oxidant levels producing condensable material. Nighttime wildfire air masses were likely influenced by increased SO2 and NO2 in the plumes leading to NO3 radical oxidation. TEM-EDX showed contributions from sulfur, carbon, and oxygen down to 20 nm particles, suggesting contributions from H2SO4 and SOA. As particle growth was previously thought to be suppressed in this isoprene-rich forest, these measurements represent a source of particles not previously considered in this environment. Chapters 5 – 6 discuss the results from field campaigns conducted in the Alaskan Arctic. In Chapter 5, I show results of A-ATOFMS and scanning electron ...
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