early soring, when the Aleutian lows are farther south. As the
western cell of the Pacific high intensifies, more debris can be
carried toward the north, so that by the time of the ¥enkee test
(Figures 3.9 and 3.10), in early May, a larger fraction of the
fallout occurred in Japan. Presumably, tests in the summer and
early fall would result in the greatest contamination of the
Japanese Islands, while winter tests would result in the least.
Also during the winter months, nrrecipitation in Javan is at a
’ minimum except for a narrow zone on the western slopes. For most
of Japan, maximum rainfall occurs during the warm season, with the
heaviest rains in June and September.
Similarly, in other inhabited regions likely to be most
affected by relatively early fallout, Mexico and Central America
to the east and the Phillipines to the west of the test area,
the dry season occurs in the winter and the rainiest in the warmer
months, so that here too, fallout would be at a minimum for winter
tests as compared to other seasons.
3.5
MAXIMUM ACTIVITY AT INDIVIDUAL STATIONS
The highest fallout reported on samcling day on an individual
gummed film at each of the stations of the network is shown in
Figures 3.12 and 3.13, together witn the burst resconsible (figure
in parentheses), the number of days after burst that the fallout
occurred and the orecinitation observed.
in d/m/ft2 corrected to sampling day.
All activity values are
As can be seen, the fifth
burst, Yankee, was responsible for the highest activity at most of
the stations. This is a result not only of the fact that Yankee
had the nighest fission yield of any of the devices tested, but
also because of the meteorological conditions associated with this
burst.
The high tronosrheric westerlies were faster, resulting
in 4 more ranid transport of debris towards the Americas.
In
addition, the winds in the eastern Sacific were from the west southWest, resulting in the vassage of fresh depris over te sout western
and soutnern states.
On the western side of tne Pacific, the normal seasonal increase
in intensity of the western portion of the Pacific high-pressure
cell and the retreat of the Aleutian low resulted in the transport
of Yankee debris towards the Japanese Islands in the lower levels,
although the direct trajectories at these levels moved generally
eastward,
- 3h -
3
SECRET