Abstract

Photochemical production and release of gas-phase NO(x) (NO + NO2) from the natural snowpack at a remote site in northern Michigan were investigated during the Snow Nitrogen and Oxidants in Winter study in January 1999. Snow was collected in an open 34 L chamber, which was then sealed with a transparent Teflon cover and used as an outdoor flow and reaction chamber. Significant increases in NO(x) mixing ratio were observed in synthetic and ambient air pulled through the sunlit chamber. [NO(x)] enhancements were correlated to ultraviolet sunlight intensity, reaching ~300 pptv under partially overcast midday, mid-winter conditions. These findings are consistent with NO(x) production from photolysis of snowpack NO3 -; the observed NO(x) release implies production of significant amounts of OH within the snow. Snowpack NO3 - photolysis may therefore significantly alter boundary layer levels of both NO(x) and oxidized compounds over wide regions of the atmosphere.

Publication Date

8-1-2000

Journal Title

Geophysical Research Letters

Publisher

Wiley

Digital Object Identifier (DOI)

10.1029/1999GL011286

Document Type

Article

Rights

Copyright 2000 by the American Geophysical Union

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