The diurnal evolution of ²²²Rn and its progeny in the atmospheric boundary layer during the Wangara experiment

J.-F. Vinuesa (1) , S. Basu (2) , S. Galmarini (1)

1 IES - JRC Institute for Environment and Sustainability
2 Department of Geosciences [Lubbock]

The diurnal atmospheric boundary layer evolution of the ²²²Rn decaying family is studied by 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 in a secular equilibrium. This study allows us to clearly analyze and identify the boundary layer processes driving the ²²²Rn and its progeny concentration behaviors. The activity disequilibrium observed in the nocturnal boundary layer is due to the proximity of the radon source and the trapping of fresh ²²²Rn 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 ²²²Rn and its progeny concentration in the unsteady growing convective boundary layer depends on the strength of entrainment events.

Domaines: Océan, Atmosphère

J.-F. Vinuesa, S. Basu, S. Galmarini. The diurnal evolution of ²²²Rn and its progeny in the atmospheric boundary layer during the Wangara experiment. Atmospheric Chemistry and Physics Discussions, 2007, 7 (3), pp.8895-8931. ⟨hal-00302897⟩