Die oberen Windströmungen und die Abscheidung von künstlichen radioaktiven Aerosolen aus der Atmosphäre

Abstract

Measurements of the concentration of atmospheric radioactivity show a distinctly seasonal variation of the course of the vertical profiles. In spring the concentration of radioactivity increases rapidly with altitude when passing from the upper troposphere into the lower stratosphere. In summer the increase is only moderate, in autumn it is low, but in winter a greater increase is observed, which reaches its maximum value during spring. Additionally a special evaluation of the worldwide Sr-90 data (1958–1965) indicates that the meridional transport of radioactive aerosols depends on the meridional distribution of the zonal wind velocity, and on the gradient of concentration created by the conditions of injection of radioactive debris from nuclear tests. Thus one may conclude, that the process of eddy diffusion is the main cause of the meridional transport and the vertical deposition of radioactive aerosols from the stratosphere. In the spring the lower stratosphere is filled by a greatly enlarged supply of radioactive material, but in the autumn the stratosphere is depleted because of the lack of supply. A tropopause mechanism is not at all necessary if the fallout phenomena are considered in this “dynamic” manner.