A process-based 222radon flux map for Europe and its comparison to long-term observations
Here we present a high-resolution <sup>222</sup>Rn flux map for Europe, based on a parameterization of <sup>222</sup>Rn production and transport in the soil. The <sup>222</sup>Rn exhalation rate is parameterized based on soil properties, uranium content, and model...
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| Autori principali: | , , , |
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| Natura: | Article (Journal) |
| Lingua: | inglese |
| Pubblicazione: |
19 November 2015
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| In: |
Atmospheric chemistry and physics. Discussions
Year: 2015, Volume: 15, Fascicolo: 22, Pages: 12845-12865 |
| ISSN: | 1680-7375 |
| DOI: | https://doi.org/10.5194/acp-15-12845-2015 |
| Accesso online: | Verlag, lizenzpflichtig, Volltext: https://doi.org/https://doi.org/10.5194/acp-15-12845-2015 Verlag, lizenzpflichtig, Volltext: https://www.atmos-chem-phys.net/15/12845/2015/acp-15-12845-2015-discussion.html 
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| Note sull'autore: | U. Karstens, C. Schwingshackl, D. Schmithüsen, and I. Levin |
| Riassunto: | Here we present a high-resolution <sup>222</sup>Rn flux map for Europe, based on a parameterization of <sup>222</sup>Rn production and transport in the soil. The <sup>222</sup>Rn exhalation rate is parameterized based on soil properties, uranium content, and modelled soil moisture from two different land-surface reanalysis data sets. Spatial variations in exhalation rates are primarily determined by the uranium content of the soil, but also influenced by soil texture and local water-table depth. Temporal variations are related to soil moisture variations as the molecular diffusion in the unsaturated soil zone depends on available air-filled pore space. The implemented diffusion parameterization was tested against campaign-based <sup>222</sup>Rn soil profile measurements. Monthly <sup>222</sup>Rn exhalation rates from European soils were calculated with a nominal spatial resolution of 0.083° × 0.083° and compared to long-term direct measurements of <sup>222</sup>Rn exhalation rates in different areas of Europe. The two realizations of the <sup>222</sup>Rn flux map, based on the different soil moisture data sets, both realistically reproduce the observed seasonality in the fluxes but yield considerable differences for absolute flux values. The mean <sup>222</sup>Rn flux from soils in Europe is estimated to be 10 mBq m<sup>−2</sup> s<sup>−1</sup> (ERA-Interim/Land soil moisture) or 15 mBq m<sup>−2</sup> s<sup>−1</sup> (GLDAS (Global Land Data Assimilation System) Noah soil moisture) for the period 2006-2010. The corresponding seasonal variations with low fluxes in winter and high fluxes in summer range in the two realizations from ca. 7 to ca. 14 mBq m<sup>−2</sup> s<sup>−1</sup> and from ca. 11 to ca. 20 mBq m<sup>−2</sup> s<sup>−1</sup>, respectively. These systematic differences highlight the importance of realistic soil moisture data for a reliable estimation of <sup>222</sup>Rn exhalation rates. Comparison with observations suggests that the flux estimates based on the GLDAS Noah soil moisture model on average better represent observed fluxes.</p> |
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| Descrizione del documento: | Im Titel ist die Zahl 222 hochgestellt Gesehen am 12.06.2020 |
| Descrizione fisica: | Online Resource |
| ISSN: | 1680-7375 |
| DOI: | https://doi.org/10.5194/acp-15-12845-2015 |