Abstract

Peroxyacetyl nitrate (PAN) was measured in ambient and snowpack interstitial air at Summit, Greenland, in June and July of 1998 and 1999 and at a rural/forest site in the Keewenaw Peninsula of Michigan in January of 1999. At Summit, we found that PAN typically represented between 30 and 60% of NOy. In the summer of 1999, a significant diel variation in both PAN/NOy and NOx/NOy was observed, but this was much less pronounced in 1998. Experiments during SNOW99 near Houghton, Michigan, indicated that PAN undergoes weak uptake onto snow grain surfaces. At Summit, we found that PAN concentrations in the snowpack interstitial air were significantly elevated (by as much as 2–5 times) relative to ambient levels, implying a flux of PAN out of the snowpack during the study period. We also observed evidence that PAN can be photochemically produced in snow that is exposed to polluted air. These observations indicate that interactions with the snowpack can have a significant impact on PAN concentrations in the boundary layer and point to potential difficulties associated with investigation of long-term changes in PAN uptake into ice cores because of the impact of postdepositional processes.

Department

Earth Sciences, Earth Systems Research Center

Publication Date

5-27-2002

Journal Title

Journal of Geophysical Research: Atmospheres

Publisher

Wiley

Digital Object Identifier (DOI)

10.1029/2001JD000547

Document Type

Article

Rights

Copyright 2002 by the American Geophysical Union.

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