On polar magnetic field reversals of the sun including the Maunder Minimum
Faculty of Sciences. Physics
9th European meeting on solar physics: magnetic fields and solar processes, vols 1 and 2
9th European Meeting on Solar Physics, SEP 12-18, 1999, UNIV FLORENCE, FLORENCE, ITALY
, p. 117-120
University of Antwerp
Polar magnetic field reversals of the Sun are discussed using H-alpha magnetic synoptic charts for 1880-1999. Correlation between the poleward migration rate of the magnetic field and the strength of the solar cycle has been obtained. It was shown that the migration rate less then 1 m s(-1) takes place in the low energetic cycles and low latitude zones of the magnetic field can not reach the poles of the Sun in the 11 year cycle and thus cannot change the sign of the field at the pole. The strength of the solar cycle determines the limit latitude which is reached by the zonal boundaries in their poleward migration. We used the sum of the yearly mean Wolf number Sigma(min)(t) W(t) from minimum activity up to polar magnetic field reversal, t. The minimum strength for a polar reversal requires Sigma(min)(t)W(t) approximate to 250, or W-max approximate to 40. Cases of very low activity solar cycles in the Maunder Minimum in which the polar magnetic field reversal was impossible, or took place in a single hemisphere only, are considered.