Jökull - 01.12.1962, Side 61

TABLE 1
Magnitude scale for C oscillations.
Maximum recorded
amplitude
Approximate field
Magni- amplitude at Palomar
tude by a pcrio'd of 25 sec
< 0.25 mm I
0.26 - 0.75 II
0.76- 2.25 III
>2.25 IV
S 0.7 microgauss
0.7 - 2.2
2.2 - 6.6
>6.6
The same scale has been uscd for all re-
corders although the sensitivity is somewhat
different.
The data on the timing, magnitude and the
periods of individual C oscillations are given
in Fig. 3 to 6. The occurence of R oscillations
accompanying tlie C oscillations is indicated in
the figures.
The data given in Fig. 3 to 6 exhibit a clear
cliurnal pattern and the frequency of occur-
rence of the oscillations increases rapidly with
increasing solar activity. The data on the sun-
spot activity are given in Fig. 13 to 16.
Moreover, there is a less conspicuous annual
pattern. The activity (magnitude by duration)
of the C oscillations appears to be at maxi-
mum at the equinoxes. The period is shorter
in the summer than in the winter ancl the
oscillations commence at a later hour of the
day in the summer.
The Ap figures for the period November 1954
to February 1957 are given in Fig. 13 to 16.
The relation of the magnitude of the C oscilla-
tions to the Ap íigure of the days on which tliey
occur is illustrated briefly in the following
Table 2.
These figures exhibit a very clear positive
correlation between the magnitude of the C
oscillations and the average Ap figure.
In studying the period pattern of C oscilla-
tions some difficulties arise from the fact tliat
a number of the indiviclual events have a wide
period band. A more elaborate spectral analysis
would be necessary in these cases.
However, in the present introductory study
it is considered permissible to base the analysis
on those events only that have a relatively nar-
row period band. A maximum band widlh of
40% has been selected. This leads to the rejec-
tion of about 100 C events out of a total of
450.
The period range 10 to 40 sec will be divided
into the 4 subranges given in Table 3. The
number of days witli C oscillations in each
range has been counted and the average Ap
íigures for the days of each range computed.
These data are given in Table 3.
Due to the clear annual variation of the
period the data in Table 3 are given for the
intervals between the equinoxes and also for
the whole recording period.
A few C events have a period range which
is divided equally between two of the subranges
(a) to (d). Such events are counted as event
on each side. Hence the i/2 values of the number
of days.
The data given in Table 3 sliow a clear and
significant statistical correlation between the
TABLE2
Average Ap figures for different magnitudes of C osciliations observecl in California.
Nov. 1. 54 to Dec. 31. 55 0 I Magnitude II III IV
Number of days 323 60 36 6 1
Average Ap (2y) 8.5 11.8 17.8 32.3 62.5
Jan. 1. 56 to Feb. 28. 57
Number of days 77 133 127 72 15
Average Ap 12.3 11.8 17.0 23.0 62.5
Nov. 1. 54 to Feb. 28. 57
Number of days 400 193 163 78 16
Average Ap 9.3 11.8 17.3 23.7 62.5
JÖKULL 59