for the field report on Shot 4 alone, but used here since these curves
typify all shots of very large magnitude. In these figures, the minimum frequency reflected from the ionosphere and detected at each
station is plotted against lcecal time, using a light line. The standard symbol "B" is used to denote times when complete absorption
appareatly prevented any lonospheric return; occasionally, for very
brief intervals during these periods, an extremely weak signal was
perceived, hence the symbols are located in the vicinity of the frequency involved.
While it is true that there are other factors influencing the
_
an
minimun frequency value, it is principally a fimction of the degree of
absorption. This may be inferred from the normaleday average~value
curves of Figs. 3.1 and 3.2. The trend of these curves indicates that
the minimum detected frequency is greatest when the stm is highest and
the absorption @hich is dus to the icnizing radiation from the sm) is
also a maximum.
.
—-—---~
Minimum detectable frequency, day of Shot 4
Ditto - occasional values during periods of
otherwise complete absorption
Ditto - rate of change unknowm
X——%——-x
Average values
8668
-
;
Tee
For 12-day period (6 days pre-
Max and min observed values
~6
E
p 88s
ceding and following Shot 4)
8
9
—_
~
o
ce
es
2
oe
&
E
=
=
=
e
3
a
H
$
06
!
1
08
i
l
10
I
Local
1
£
2
time (heurs}
!
14
1
1
16
18
Fige 3.2 = Minimum Frequency Detected at Site Elmer for Day of Shot 4,
Compared with Normal Valves
2h
SEC eT