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.
Geophysical Research Letters
Digital Object Identifier (DOI)
R. E. Honrath, M. C. Peterson, M. P. Dziobak, J. E. Dibb, M. A. Arsenault, and S. A. Green, "Release of NOxfrom sunlight-irradiated midlatitude snow," Geophysical Research Letters, vol. 27, no. 15, pp. 2237–2240, Aug. 2000.
Copyright 2000 by the American Geophysical Union