Lead-212, radon and vertical mixing in the lower Atmosphere (100–2000)m

Abstract

This paper summarizes 5 vertical soundings of lead-212 concentrations in the lower atmosphere, in 3 of which lead was measured together with radon. The measurements were made in stable weather and under light winds conditions in the South West of France. There was general agreement among radon and lead and the stability of the atmosphere, which indicate a semi-steady state situation. Using radon and lead profiles we use an advection diffusion model to estimate the mean vertical motion and the vertical diffusion. The results indicate downward wind of less than 1 cm/sec and vertical mixing which is very sensitive to stability. For Brunt-Väisäla frequency N² = 3.5 × 10^-4 sec^-2 which is characteristic of isothermal atmosphere K ≈ 1 m2/sec. For a profile which is half adiabatic (N² = 1.7 × 10^-4 sec^-2) K = 10 m²/sec, where N² is smaller than 5 × 10-5 sec-2, K is greater than 40 m2/sec. These estimates were obtained on different days for levels of similar stabilities.DOI: 10.1111/j.2153-3490.1973.tb00621.x