 |
| Titel |
Factors controlling temporal variability of near-ground atmospheric ²²²Rn concentration over central Europe |
| VerfasserIn |
M. Zimnoch, P. Wach, L. Chmura, Z. Gorczyca, K. Rozanski, J. Godlowska, J. Mazur, K. Kozak, A. Jeričević |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 18 ; Nr. 14, no. 18 (2014-09-16), S.9567-9581 |
| Datensatznummer |
250119028
|
| Publikation (Nr.) |
 copernicus.org/acp-14-9567-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Concentration of radon (222Rn) in the near-ground atmosphere has been measured
quasi-continuously from January 2005 to December 2009 at two continental
sites in Europe: Heidelberg (south-west Germany) and Krakow (southern
Poland). The atmosphere was sampled at ca. 30 and 20 m above
the local ground. Both stations were equipped with identical instruments.
Regular observations of 222Rn were supplemented by measurements of
surface fluxes of this gas in the Krakow urban area, using two different
approaches. The measured concentrations of 222Rn varied at both sites
in a wide range, from less than 2.0 Bq m−3 to approximately
40 Bq m−3 in Krakow and 35 Bq m−3 in Heidelberg. The mean 222Rn
content in Krakow, when averaged over the entire observation period, was 30%
higher than in Heidelberg (5.86 ± 0.09 and 4.50 ± 0.07 Bq m−3, respectively). Distinct seasonality of 222Rn signal
is visible in the obtained time series of 222Rn concentration, with
higher values recorded generally during late summer and autumn. The surface
222Rn fluxes measured in Krakow also revealed a distinct seasonality,
with broad maximum observed during summer and early autumn and minimum
during the winter. When averaged over a 5-year observation period, the
night-time surface 222Rn flux was equal to 46.8 ± 2.4 Bq m−2 h−1.
Although the atmospheric 222Rn levels at Heidelberg and
Krakow appeared to be controlled primarily by local factors, it was possible
to evaluate the "continental effect" in atmospheric 222Rn content
between both sites, related to gradual build-up of 222Rn concentration
in the air masses travelling between Heidelberg and Krakow. The mean value
of this build-up was equal to 0.78 ± 0.12 Bq m−3. The measured minimum
222Rn concentrations at both sites and the difference between them was
interpreted in the framework of a simple box model coupled with HYSPLIT
(Hybrid Single Particle Lagrangian Integrated Trajectory)
analysis of air mass trajectories. The best fit of experimental data was
obtained for the mean 222Rn flux over the European continent equal to
52 Bq m−2 h−1, the mean transport velocity of the air masses within
the convective mixed layer of the planetary boundary layer (PBL) on their route from the Atlantic coast to
Heidelberg and Krakow equal to 3.5 m s−1, the mean rate constant of
222Rn removal across the top of the PBL equal to the 222Rn decay
constant and the mean height of the convective mixed layer equal to 1600 m. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|