On the epochs of polarity reversals of the polar magnetic field of the sun during 1870-1982

Abstract

The H-alpha synoptic charts for the 1904-1982 period and data on the polar prominences for the 1870-1905 period are used to investigate the polarity reversal of the polar magnetic field on the sun for 11 solar cycles. Good agreement is found between polarity reversals obtained from the drift trajectory of the neutral line and those from magnetograph observations. A three-fold polarity reversal of the sun's magnetic field was found in the 12th and 14th solar cycles in the southern hemisphere, and in the 16th, 19th and 20th solar cycles in the northern hemisphere. It is noted that the filament bands in the two hemispheres do not reach the respective poles simultaneously.