The diurnal evolution of ²²²Rn and its progeny in the atmospheric boundary layer during the Wangara experiment
The diurnal atmospheric boundary layer evolution of the <sup>222</sup>Rn decaying family is studied using a state-of-the-art large-eddy simulation model. In particular, a diurnal cycle observed during the Wangara experiment is successfully simulated together with the effect of diurnal va...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2007-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/7/5003/2007/acp-7-5003-2007.pdf |
| Summary: | The diurnal atmospheric boundary layer evolution of the <sup>222</sup>Rn decaying family is studied using a state-of-the-art large-eddy simulation model. In particular, a diurnal cycle observed during the Wangara experiment is successfully simulated together with the effect of diurnal varying turbulent characteristics on radioactive compounds initially in a secular equilibrium. This study allows us to clearly analyze and identify the boundary layer processes driving the behaviour of <sup>222</sup>Rn and its progeny concentrations. An activity disequilibrium is observed in the nocturnal boundary layer due to the proximity of the radon source and the trapping of fresh <sup>222</sup>Rn close to the surface induced by the weak vertical transport. During the morning transition, the secular equilibrium is fast restored by the vigorous turbulent mixing. The evolution of <sup>222</sup>Rn and its progeny concentrations in the unsteady growing convective boundary layer depends on the strength of entrainment events. |
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| ISSN: | 1680-7316 1680-7324 |