RADIOACTIVITY IN THE SOUTHERN STRATOSPHERE
419
45°N in the first half of 1959 suggest an appearance of Orange debris
in the polar stratosphere of the northern hemisphere about six months
after its production. Unfortunately, even fewer data from the southern
hemisphere are available for this period. The presence of Starfish
debris at 34°S in December 1962 may be explained by the rapid meridional movement of material at very high altitudes followed by subsidence
into the polar stratosphere and circulation toward the equator in the
southern-hemisphere summer. The scant !%cq data for mid-1963 at
45°N and 65°N tend to confirm such a distribution pattern. The ab-
sence of '°Cd at 31°N in this period probably reflects the relatively
slower mixing into low latitudes which occurs in the hemispheric
winter.
Data for ‘*Rh (Ref. 11) and ‘%Cad concentrations at 31°N in the
second spring after the Orange and Starfish shots, respectively, are
given in Table 4. The relative concentrations at a given altitude are
Table 4— RHODIUM-102 AND CADMIUM-109 AT 25 TO 35°N ABOUT
20 MONTHS AFTER PRODUCTION
102Rh,
10Cq,
Altitude, ft
dis/min per 10° scf*
dis/min per 103 scft
105 ,000
90,000
80,000
65 ,000
130-200
50— 80
20-130
18~—21
10-13
7—12
0-3
Estimated production
|
3 Mc
0.25 Mc
*As of Aug. 11, 1958.
tAs of July 9, 1962.
consistent with the estimated production for these tracers: about 3 Mc
of '"Rh (Ref. 12) and about 0.25 Mc of !"cd (Ref. 7).
The levels of Sr due to Starfish may be determined from the observed 'cq levels and the value for '"ca/*Sr of 3.5 estimated above
for this device. Although these "Sr levels may be relatively consistent,
they are subject to bias introduced because of the uncertainties in the
ratio.
At 31°N the fraction of "Sr attributed to Starfish on the basis of
this estimated ratio was generally less than a few percent through
1963, increasing to about 10% at 105,000 ft in 1964.
For 34°S Starfish *Sr concentrations are given in the last column
of Table 3 for comparison with those attributable to the 1961 U.S.S.R.
tests.
Although debris attributed to both the 25-Mt 1961 U.S.S.R. device
and Starfish was present at 105,000 ft in December 1962 and April 1963
at 34°S, significant differences in its distribution in the southern hemi-