Meteorological factors contributing to the interannual variability of midsummer surface ozone in Colorado, Utah, and other western U.S. states
We use daily maximum 8âh average surface Oâconcentrations (MDA8) for July 1995-2013, meteorological variables from the National Center for Environmental Prediction/National Center for Atmospheric Research Reanalysis, the North American Regional Reanalysis, and output from regional chemistry-climate simulations to assess relationships between Oâ and weather in the western U.S. We also explore relationships among July Oâ, satellite-derived NOâ, and meteorology. A primary objective of this study is to identify an effective method for correcting the effects of meteorology on July MDA8. We find significant correlations between July MDA8 Oâ and meteorological variables for sites in or near Denver, Colorado, and Salt Lake City, Utah. The highest correlations were for 500âhPa heights, surface temperatures, and 700âhPa temperatures and zonal winds. We conclude that increased 500âhPa heights lead to high July Oâ in much of the western U.S., particularly in areas of elevated terrain near urban sources of NOâ and other Oâ precursors. In addition to bringing warmer temperatures and fewer clouds, upper level ridges decrease winds and allow cyclic terrain-driven circulations to reduce transport away from sources. Because of strong, nearly linear responses of July MDA8 to 500âhPa heights, it is not reasonable to use uncorrected trends in peak Oâ for assessments of the effectiveness of emissions controls for much of the western U.S. Robust linear regressions for July MDA8 and tropospheric NOâ with 500âhPa heights can be used to assess and correct trends in July MDA8 in the Intermountain West.
document
https://n2t.org/ark:/85065/d78k7bp7
eng
geoscientificInformation
Text
publication
2016-01-01T00:00:00Z
publication
2016-03-16T00:00:00Z
Copyright 2016 American Geophysical Union.
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