RADIOACTIVITY ALONG THE 80TH MERIDIAN
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ATMOSPHERIC NUCLEAR TESTS
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TFMAMJUASOND JFMAMJIASONDUJFMAMJJA SOND JFMAMJJASOND JFMAMI VA SONI
1958
1959
1960
1961
1962
Fig. 3-—Tropospheric burdens of gross fission-product radioactivity.
This activity was confined principally to the north temperate zone
although sensitive radiochemical analyses did indicate the presence of
short-lived fission products from the first French test throughout the
northern hemisphere and as far south as Antofagasta, Chile.’*:'® The
small peak in the southern-hemisphere burden during March 1960 is
also due to French nuclear debris.
The southern-hemisphere burdens do not show any true seasonal
trends. This may be variously explained by differences in the meteo-
rology of the two areas, by transequatorial migration of debris during
the higher spring peak of the northern hemisphere which serves to
cover up the southern-hemisphere fall minimums, or by the different
stratospheric distribution of debris in the two hemispheres. The last
explanation seems to be the most reasonable one. Activity concentra-
tions in the southern hemisphere during the moratorium were ex-
tremely low compared to those north of the equator, with the disparity
increasing with increasing latitude; consequently there apparently was
less stratospheric debris in a position to be affected by the winter—