Author(s)

Stanley G. Edwin^1,2, Nicole Mölders^2,3

¹Council of Athabascan Tribal Governments, Fort Yukon, USA.
²Department of Atmospheric Sciences, College of Natural Science and Mathematics, University of Alaska Fairbanks, Fairbanks, USA.
³Geophysical Institute, University of Alaska Fairbanks, Fairbanks, USA.

Near-surface PM_2.5 and meteorological observations were performed in three rural communities in the high latitude Yukon Flats valley at various times during the cold season (October to April). These data were synthesized with data from other meteorological sites, NCEP reanalysis and MAIAC retrieved aerosol optical depths data to analyze the role of mesoscale processes and radiation on air quality. Under weak large-scale forcing mountain-valley circulations develop that are driven by the differences in insolation. During the long dark nights, radiative cooling occurs in the near-surface layer of the mountain slopes of the Brooks, Ogilvie and White Mountains Ranges and at the bottom of the valley. Here surface-based inversions (SBI)—known as roof-top inversions—forms, while the cold air drains from the slopes. A frontal wedge forms when the cold air slides over the relatively colder air in the valley. Drainage of cold air from the Brooks Range governed the circulation and cold air pooling in the valley. Concentrations during times with and without SBI differed significantly (at 95% confidence) at two sites indicating that local emissions were the major contributor. At the site, which is closest to the mountains, concentrations marginally changed in the presence of inversions. At all sites, 24-h mean PM_2.5 remained below the National Ambient Air Quality Standard.

Yukon Flats Air Quality, Winter Roof-Top Inversions, High Latitudes, Mesoscale Circulations, Radiative Cooling, Cold Air Pooling, Aerosols, PM_2.5

Edwin, S. and Mölders, N. (2020) Mesoscale Impacts on Cold Season PM_2.5 in the Yukon Flats. Journal of Environmental Protection, 11, 215-240. doi: 10.4236/jep.2020.113013.