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Two north‐south sections of the atmospheric concentration of 85 Kr are presented. The most striking feature of these sections is a large concentration jump at the respective geographical position of the intertropical convergence. In October 1980 the 85 Kr concentration of the northern hemisphere was about 1.5 pCi/m 3 higher than the one observed in the southern hemisphere. Due to a temporal increase of the northern 85 Kr concentrations the concentration difference observed in March/April 1981 was 2.5 pCi/m 3 . Hemispheric residence times of 1 and of 1.7 years are estimated from the two 85 Kr sections. The poleward increase of the northern 85 Kr concentrations is in agreement with a meridional diffusivity of 1.6×10 10 cm 2 /s. Five years of a continuous 85 Kr record from two stations at 47.9°N, 7.8°E (difference in altitude 1000 m) are presented. The data show a temporal increase of 0.5 pCi m −3 yr −1 , a seasonal variability with an amplitude of 1–2 pCi/m 3 , and numerous peaks. Most of the peaks originate from European 85 Kr sources. It is estimated that the yearly contribution of these sources to the global 85 Kr discharge is at least 10%. The seasonal variability of the 85 Kr concentrations is tentatively explained by the seasonality of the vertical mixing intensity within the lower atmosphere.
Weiß et al. (Thu,) studied this question.