Inverted SC in the Low Latitude Regions
In the low and middle latitudes, the horizontal component of the main impulse of SC's usually increases. But, from some observatories, SC's of the decreasing horizontal component (inverted SC) are reported, though their frequencies are very small. In this paper, the two inverted SC, observed at rather more observatories in the low and middle latitudes are examined somewhat in details. The results show that one at 04h 59m, April 2nd, 1958 is a s.f.e. and the other at 07h 18m, Jan. 10th, 1960 would be better classified as Si (magnetic sudden impulse).
The suitable classification of the rapid variations is often difficult, based on the record of only one station and this examination is made by means of the world wide data. It is suggested that the horizontal component of the main impulse of SC may always increase in the low latitude regions near Kakioka.