On Geomagnetic Storms, which occurred during the period from July 1957 to Dec. 1968, and Quality of ssc.
The author have felt the necessity to determine more rigorously the Quality which is one of three classes A, B and C, given to a phenomenon of magnetic rapid variation according to its quality.
In this paper the Quality of ssc is studied as a first step. The author proposes a chart to determine the Quality of ssc more rigorously.
To derive the chart about 250 geomagnetic storms with sudden commencement observed at Kakioka, Memambetsu and Kanoya observatories during the period from July, 1957 to December, 1968 are studied, and the following results are obtained:
(1) A positive correlation is found between amplitudes of ssc and ranges of storm at each observatories.
(2) For storms occurring from 06h to 10h (Local time), the amplitude of sudden commencement in declination is larger than in horizontal intensity. Such cases of larger declination are about 9% of the whole.
In storm ranges similar cases of larger declination than horizontal intensity are about 30% of the whole.
(3) Ranges of Sq change in parallel with solar activities. Their maximums appear in equinox of most active sun year and minimums in winter of most quiet sun year. Changes in declination are generally larger than in horizontal intensity. The amount of those changes is about 70γ between maximum and minimum.
Using these results, the charts applied to above three observatories are made to determine the Quality of ssc.