473
GROSS BETA ACTIVITY, PC/M?
RELATION OF INDEX PATTERNS TO FALLOUT PEAKS
ptt
J
|
F
|
M
i
i
A
|}
MJ
|
J
tf
A
§
1963
es
N
ee
OD
J
F
M
A
MJ
1964
Fig, 2—-Mean monthly area-averaged gross beta activity in air over
the United States after the test ban of December 1962. Lower curve
(---)
represents
actually
measured
radioactivities and shows a
pronounced spring maximum of fallout in 1963 with a lesser peak in
the spring of 1964. Middle curve (—) represents the measuredfallout
adjusted to a common age of 100 days by the decay curve of Fig. 3.
Upper curve (—--) gives the fallout intensity of the lower curve ad-
justed to age 100 days by the well-known empirical formula AT!=
constant. From the discrepancy between the two upper curves, it is
evident that this formula is invalid for longer-lived fallout samples.
initial and final values of the cyclone index over the period of decrease,
and At is the time in days over which the decrease occurred) (see
Table 2). It was concluded from the data in Table 2 that any value of
[100(C, ~ C,)]/At measured to be significantly greater than 3.5 would
probably produce an increase in surface fallout (over that of the mean
seasonal value)
a short time later. This increase has interesting
implications in that it indicates a possibility of constructing a prediction model for the shorter period fallout fluctuations. However, it must
be pointed out that the validity of this inference is not completely
certain because of the relatively short time period over which the
analysis was performed. Furthermore, no significant relation could be