Journal Article

PreJuSER-12494

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png NO2 photolysis frequencies in street canyons

Koepke, P. ; Garhammer, M. ; Hess, M. ; Roeth, E.-P.FZJ*

2010
EGU Katlenburg-Lindau

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Please use a persistent id in citations: http://hdl.handle.net/2128/10047  doi:10.5194/acpd-10-12827-2010

Abstract: Photolysis frequencies for NO2 are modeled for the conditions in urban streets, which are taken into account as canyons with variable height and width. The effect of a street canyon is presented with absolute values and as a ratio RJ of the photolysis frequency within the street compared to that with free horizon. This allows further use of the existing photolysis parameterizations. Values are presented for variable solar elevation and azimuth angles, varying atmospheric conditions and different street properties. The NO2 photolysis frequency in a street depends strongly on the relative width of the street and its orientation towards the sun. Averaged over atmospheric conditions and street orientation, the NO2 photolysis frequency is reduced in comparison with the values for free horizon: to less than 20% for narrow skyscraper streets, to about 40% for typical urban streets, and only to about 80% for garden streets. A parameterization with the global solar irradiance is given for the averaged RJ values.

Keyword(s): J

Note: Financial support by the German Umweltbundesamt under UFOPLAN Grant 370942207 is gratefully acknowledged.

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Research Program(s):

1. Atmosphäre und Klima (P23)

Appears in the scientific report 2010

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