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Question:
Which Month Experienced
the Highest 8-Hour Daily Maximum Ozone Concentration for the
Following Sites?
Answer:
Glacier National Park - May (2008), June (2009),
and May (2010)
Yellowstone National Park - April (2008), Sept* (2009), and April
(2010)
Denali National Park - April (2008), April (2009), and April
(2010)
Trinidad Head - April (2008), April (2009), and March (2010)
*The US EPA notes in its database that September 2009 ozone readings
were affected by a wildfire in Yellowstone National Park. The
second highest 8-hour average ozone concentration at the site
was in May.
The Springtime
Months of April and May Predominated
The highest 8-hour daily maximum concentration
occurred for most of the sites during the spring months. Lefohn
et al. (2001) and Oltmans et al. (2008) discuss the variability
of background ozone. The ozone monitoring site at Trinidad Head,
CA is a site that many times meets the criteria for identifying
surface ozone policy-relevant background levels. For more information
about policy-relevant background, please click
here. An
Internet-based slide
presentation
is available for purposes of previewing the Lefohn et al. (2001)
paper.
For more information about background
ozone and ozone trends, please visit our publication
web page.
References
Lefohn A. S., Oltmans S. J. , Dann
T. , and Singh H. B. (2001) Present-day variability of background
ozone in the lower troposphere. J. Geophys. Res., 106 (D9):9945-9958.
Oltmans S. J., Lefohn A. S., Harris J. M., and Shadwick
D. (2008) Background ozone levels of air entering the west coast
of the U.S. and assessment of longer-term changes. Atmospheric
Environment. 42:6020-6038. |
