The Diurnal Evolution of 222-Rn and its Progeny in the Atmospheric Boundary Layer during the Wangara Experiment

The diurnal atmospheric boundary layer evolution of the 222-Rn 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 222-Rn 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 222-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 222-Rn and its progeny concentration in the unsteady growing convective boundary layer depends on the strength of entrainment events.

VINUESA Jean;  BASU Sukanta;  GALMARINI Stefano; 

2007-07-10

EUROPEAN GEOSCIENCES UNION

JRC37266

https://publications.jrc.ec.europa.eu/repository/handle/JRC37266,