The eastward moving debris reached the Americas on March 7
and 8, indicating an average west wind of about 0 knots, in good
agreement with the few wind observations available in the upper
troposphere. Although the progression of debris to the west
appears to be in good agreement with the 5,000-feoct trajectory,
indicating that the transport occurred in the trade wind layers,
it is entirely possible that stratospheric debris moving with the
upper lewel easterlies contriluted to this fallout also.
The most striking fact which emerges from a study of the
fallout in the period following the Bravo test is the tendency
for the debris to remin in the tropical latitaies. By far the
largest amounts of fallow occurred in the latitude bend from
10°S to 20°N, with occasional excursions into the more temperste
latitudes of esch hemisphere, particularly in the Americas. An
example of this can be seen in the southwestern United States in
the period beginning March 15,
At this time, a deep low pressure
system extending through most of the troposphere was located just
off the west coast, with strong southwesterly winds over the
southwestern states. This depression moved slowly eastward so that
by Maveh 18th, the southwesterly winds were over the Mississippi
Valley. . dn: examination of the fallout maps reveals that fallout
during this period was associated with the soutismsterly winds,
which carried debris from the tropical regions.
It is significant
that this fallout was independent of precipitation.
The highest
fallout values occurred during the first three days of the period
when there was no precipitation, and even on the 18th, when there
were severel stations reporting precipitation, the fallout occurred
in the region dominated by the southwesterly winds and was not
closely associated with the existence of precipitation.
A somewhat
similar series of events occurred in the period March 21-25, although
precipitation was more widespread in this case and may have had
more influence on the observed fallout patterns.
2.2
ROMEO
The second burst of the Castle series, Romeo, also a high-yield
burst of the same order of magnitude es the Bravo test, was detonated
from a barge st 1830 GCT, March 26, 1954. The resulting cloud of
debris reached to 110,000 feet, with the base of the mushroom top
at 62,000 feet.
The wind observations associated with this burst
showed light easterly winds at virtually all levels increasing in
speed above 80,000 feet to a maximum of 92 knots from the SE at the
top of the highest observation, 95,000 feet. Although the trajectories
(Figure. 2.3) at all levels in the troposphere moved westward
initially, the 30,000- and 0,000-foot trajectories curved northward
-~
J
=