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| Titel |
On the use of radon for quantifying the effects of atmospheric stability on urban emissions |
| VerfasserIn |
S. D. Chambers, A. G. Williams, J. Crawford, A. D. Griffiths |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 3 ; Nr. 15, no. 3 (2015-02-02), S.1175-1190 |
| Datensatznummer |
250119384
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| Publikation (Nr.) |
 copernicus.org/acp-15-1175-2015.pdf |
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| Zusammenfassung |
| Radon is increasingly being used as a tool for quantifying stability
influences on urban pollutant concentrations. Bulk radon gradients are ideal
for this purpose, since the vertical differencing substantially removes
contributions from processes on timescales greater than diurnal and
(assuming a constant radon source) gradients are directly related to the
intensity of nocturnal mixing. More commonly, however, radon measurements
are available only at a single height. In this study we argue that
single-height radon observations should not be used quantitatively as an
indicator of atmospheric stability without prior conditioning of the time
series to remove contributions from larger-scale "non-local" processes. We
outline a simple technique to obtain an approximation of the diurnal radon
gradient signal from a single-height measurement time series, and use it to
derive a four category classification scheme for atmospheric stability on a
"whole night" basis. A selection of climatological and pollution
observations in the Sydney region are then subdivided according to the
radon-based scheme on an annual and seasonal basis. We compare the
radon-based scheme against a commonly used Pasquill–Gifford (P–G) type
stability classification and reveal that the most stable category in the P–G
scheme is less selective of the strongly stable nights than the radon-based
scheme; this lead to significant underestimation of pollutant concentrations
on the most stable nights by the P–G scheme. Lastly, we applied the
radon-based classification scheme to mixing height estimates calculated from
the diurnal radon accumulation time series, which provided insight to the
range of nocturnal mixing depths expected at the site for each of the
stability classes. |
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