Development of Polar Geomagnetic Disturbance and PCA Event on February 11, 1958
Nagai, M. & Hakura, Y.
Abstract
An investigation was made on the development of ionospheric and geomagnetic storms caused by solar corpuscular clouds emitted from a major flare that appeared at 21:08 UT on February 9,1958.
Several interesting characteristics are discussed in the present analysis on the relation between the world-wide patterns of ionospheric disturbances and the corresponding current systems of geomagnetic storms, such as simultaneous occurrence of a peculiar polar disturbance with sudden development of PCA in the auroral zone far preceding the sudden commencement and appearance of the transient stage removed from Spq-field to DP(Pre SC)-field, unusual increase of ionization right before the onset of the sudden commencement over the whole polar cap, outstanding two-stepped expansions of the region of polar cap blackouts and equivalent current systems of two successive sudden commencements, and variations of directions of the straight currents flowing in the central part of the polar cap.
