983241 - Seasonal and Spatial Trends in Urban and Rural PM2.5 Speciated Aerosol Composition Data from 2016-2019

Characterizing the spatial and seasonal variability in the composition of major aerosol species is essential for estimating their contribution to PM2.5 total mass concentration and visibility degradation. The IMPROVE (Interagency Monitoring of Protected Visual Environments) network, which began in 1988, operates in mostly remote/rural areas throughout the United States. The Chemical Speciation Network (CSN) began in 2000 and is operated by the Environmental Protection Agency at mostly urban/suburban monitoring sites across the United States. The IMPROVE and CSN networks have similar sampling schedules and analysis methods in order for data to be aggregated. Combined, data from the IMPROVE and CSN networks provide the opportunity to investigate/explore the seasonal distribution of major aerosol species as a function of geographical region, including the differences in seasonality between urban and rural locations. We examine the 2016-2019 monthly mean mass concentrations of ammonium sulfate, ammonium nitrate, particulate organic matter, elemental carbon, and mineral dust aerosols, as well their relative contribution to PM2.5 mass concentrations. Evaluating the monthly mean distributions for major aerosol species as a function of geographic region (especially differences in urban and rural concentrations) is necessary for understanding the impacts of emission sources, regional transport, and atmospheric processes governing aerosol concentrations in the atmosphere.