Time-series analysis of radon concentrations for Bengaluru's atmosphere.

The Fast Fourier Transform (FFT) analysis of the activity concentration of radon and selected meteorological parameters was carried out at Department of Physics, Bangalore University, Bengaluru (12056'44"N, 77030'25″E, 840 m above MSL). All of the measured parameters, with the exception of pressure, showed a clear diurnal trend, which can be explained by the presence of typical atmospheric processes such as temperature inversion in the morning and greater vertical mixing in the afternoon. Radon's time series has a latent memory of sub-diurnal cycles, as shown via FFT analysis. The monthly average radon has higher levels of activity during winter months compared with monsoon and summer months. Days during the monsoon season had the lowest radon activity, which may be ascribed to the fact that less radon was being exhaled from the soil as a result of the rain. Radon was recorded at 8.06 ± 0.56 Bq/m3, temperature at 28.9 °C, humidity at 55.2% and pressure at 918 mbar.