Spatial and seasonal variability in fine mineral dust and coarse aerosol mass at remote sites across the United States. Issue 5 (15th March 2017)

• Record Type: Journal Article
• Authors: Hand, J. L.; Gill, T. E.; Schichtel, B. A.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 5(2017)
• Page Start: 3080
• Page End: 3097
• Publication Date: 2017-03-15
• Subjects: fine mineral dust -- coarse mass -- seasonality -- remote United States; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2016JD026290
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Understanding the spatial and temporal variability in fine mineral dust (FD, mineral aerosols with diameters less than 2.5 µm) and coarse aerosol mass (CM, mass of aerosols with diameters between 2.5 and 10 µm) is important for accurately characterizing and perhaps mitigating their environmental and climate impacts. The spatial and seasonal variability of ambient FD and CM was characterized at rural and remote sites across the United States for 2011–2014 using concentration and elemental chemistry data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) aerosol monitoring network. FD concentrations were highest (and had ≥50% contributions to PM2.5 mass) in the southwestern United States in spring and across the central and southeastern United States in summer (20–30% of PM2.5 mass). CM was highest across the Southwest and southern Great Plains in spring and central United States in spring, summer, and fall (≥70% contributions to PM10 mass). Similar FD and CM seasonal variability was observed near source regions in the Southwest, but a seasonal decoupling was observed in most other regions, suggesting the contribution of nonlocal sources of FD or perhaps non‐dust‐related CM. The seasonal and spatial variability in FD elemental ratios (calcium, iron, and aluminum) was fairly uniform across the West; however, in the eastern United States a shift in summer elemental composition indicated contributions from nonlocal source regions (e.g., North Africa). Finally, long‐term trend analyses (2000–2014) indicated increased FD concentrations during spring at sites across the Southwest and during summer and fall in the southeastern and central United States. Key Points: Fine mineral dust and coarse aerosol mass varied significantly both seasonally and spatially at remote sites across the United States Elemental composition of fine mineral dust suggests influence from long‐range transport from North Africa and Asia to the United States Increases in fine mineral dust concentrations have occurred in the Southwest in spring and Midwest in summer and fall