Morphological Study on Sudden Commencements of Magnetic Storms and Sudden Impulses ( IV )
In this paper are presented the results of the morphological study on sudden impulses, si's, concerning a few characteristics of the horizontal disturbance vector changes in high latitudes, and their individual equivalent current systems at several successive stages. These results are compared with the morphology of sudden commencements of magnetic storms, ssc's, which is obtained in the previous papers. It is found that si's differ slightly from ssc's in a character concerning the occurrence distribution of the polarity of the vector change, but are quite similar in the other characters. Various kinds of equivalent current systems of si's which show some great different features from each other are found. Of course, the ones which show a pronounced similarity to those of ssc's are also found.