accurate observations of the character of the cloud.
The winds were easterly to 5,000 feet,
light southerly above to about 30,000 feet, becoming westerly
about 30-0 knots to the tropopause.
Secause of large amounts of
fattout from the second burst, which occurred eleven days earlier,
it was impossible to trace the history of the debris from Koon.
According to the meteorological trajectories (Figure 2.4), the
lowest layers moved westward, the mid-tropospheric portion milled
about to the north of the Marshalls for many days and the upper
portion moved eastward, remaining south of the Hawaiian Islands,
reaching the southwestern states on April 13.
No fallout station
reported debris which can be definitely assigned to this burst,
although it is likely that some of the activity assigned to Romeo
is a mixture of debris from the two bursts.
assigned to Koon in this report.
2.4 UNION
No fallout has been
y
&
The fourth test of the series, Unions detonated at Bikini at
1810 GCT, April 25, 19She
The wind pattern was
‘typical, easterly tradesin the lower levels, light winds above,
becoming westerly near the tropopause, and strong easterlies above
70,000 feet. Trajectories of this burst are shown in Figure 2.5.
If the 30,000- and 40,000-foot trajectories are correct, very little
fallout was evident from these levels, since no debris was detected
in Mexico or along the Gulf cosst wmtil May 5 or later. Fallout at
Medford, Ore., on May 2 and in the western states on the following
days is in good agreement with the 148,000-foot meteorological
trajectory. It is very possible that the lack of mateorological
data resulted in erroneous trajectories st 30,000 and 40,000 feet,
since debris arriving in Central and South America on May 5 was
most likely transported at these levels, Fallout to the west of
Bikini seened to be in good agreement with the trajectcries.
It
Should be noted that even though a month had elacsed since the last
burst, considerable fallout is occurring tnroughout the
tropics mpd It is by no means certain that the debris assigned to
Union is not from an earlier burst, or that some of the activity
Bssumed to be from Romeo is not actually from Union.
—_¥
2.5 YANKEE
=
Yankee, the fifth burst of thé°S@Pies, wasdetonated from
Bikini at 1810 GCT, May h, 195h.
bh
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