222Rn concentration in the outdoor atmosphere and its relation to the atmospheric stability

The radon in the outdoor atmosphere has been monitored continuously since 1991. On the basis of the measured data mainly the average daily and the average annual courses of the 222Rn concentrations have been studied. The annual courses of 222Rn concentration are similar for all years. They present the annual variations. The average course of the 222Rn concentration calculated on the basis of all continual measurements in the years 1991-1997 reaches the maximum value in October and the minimum value in April. The average daily courses of the 222Rn concentration for the individual months of the year. The average daily courses have a form of waves with a maximum in the morning hours and with a minimum in the afternoon. The maximal amplitudes of daily waves have been reached in the summer months, from June till August. The amplitudes of daily waves are very small at the end of an autumn and during the winter months. The analysis of the daily waves and annual courses of 222Rn showed that the amplitudes of the daily waves are in proportion to the global solar radiation irradiating the Earth's surface. The day duration influence on the phase of the daily wave and the wind velocity influence mainly on the level of the radon concentration. For the study of the relation of the radon concentration in the outdoor atmosphere to the stability the data of the atmosphere were obtained and they were correlated with the radon concentration. The results indicate that the 222Rn concentrations int he outdoor atmosphere could be used for determination of the vertical atmospheric stability and these ones could reflect the atmospheric stability more completely than the different classifications based on the knowledge pertinent to the meteorological parameters. (authors)