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LATITUDE
Fig. 11—Comparison of latitudinal distribution of total Sr deposition
from lower stratospheric injections in equatorial and polar regions.
from a polar period than from an equatorial period. Figure 10 compares
the fallout rates for a lower equatorial, high atmospheric source. Although little fallout reaches the earth’s surface during the first year
from the high-altitude source, the deposition rate remains constant after
the second year for an extended period, There is at least one further
piece of information necessary to complete the prediction: the knowledge
of the geographical distribution of the “Sr deposition. This distribution
is given in Fig. 11. Debris from an equatorial injection partitions
equally between hemispheres, but the deposition peaks in temperature
latitudes. Strontium-90 introduced into the lower polar stratosphere re-
mains largely in the northern hemisphere. Within each latitude band
there are also variations depending on rainfall and other factors.!°
DASA has produced models similar to that just described in which
the atmosphere is subdivided into characteristic boxes. DASA’s model
is computerized. However, it assumes the exponential model with dif-
ferent residence times in various boxes.
Telegadas and List’* have suggested a schemefor the prediction of
fallout based on the stratospheric content of “Sr in the lower polar
stratosphere. The arguments for the use of this volume of the atmosphere derive both from meteorological considerations and the findings
of the Orange rocket ‘Rh experiment. Table 4 shows verification of
the annual fallout relative to the stratospheric Sr content in the volume