Box model for radon transfers into the stratosphere

There is experimental evidence that the stratospheric reservoir of Pb-210 aerosols is fed from the troposphere by injections into the stratosphere of its mother nuclide Rn-222. In steady state conditions, it is possible to calculate, for the tropospheric air penetrating into the stratosphere, that an Rn-222 concentration of 10 pCi kg^-1 is necessary to balance the stratospheric Pb-210 losses. This concentration is not typical of the values usually measured in the upper troposphere. This supports the idea that the troposphere-to-stratosphere transfers are discontinuous and occur following a strong tropospheric upward transport.