Low-Altitude Input of Artificial Radioactivity to a Severe Convective Storm—Comparison with Deposition

Abstract

Concentrations of artificial radioactivity and plant pollens in rain have been found to vary in phase during convective storms. Because pollens are tracers for low-altitude air, this result is most simply explained by low-altitude input of both pollens and radioactivity in the convective updraft. The low-altitude input hypothesis was tested by mass-budget methods. Comprehensive mesometeorological and radio-chemical data collected from a segment of the severe squall line in central Oklahoma on 10 May 1964 were used in the analysis. The radioactivity inflow rate below 650 mb was estimated kinematically using serial soundings in the storm inflow and the concentration of radioactivity in ground-level air. Total input was computed by multiplying the inflow rate by the time required for the storm to cross a network of 10 ground-level rain samplers. Comparison of inflow and deposition over the sampler network shows that inflow of airborne radioactivity to the storm at low altitudes can account for artificial radioactivity deposited in the rain.