Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 58, p. 17-21 (2018)
Reversal of Sun’s polar magnetic field in solar cycle
M. Pishkalo, PhD
Astronomical Observatory of Taras Shevchenko National University of Kyiv, Kyiv
Abstract
The connection of solar activity expressed by international sunspot (Wolf) numbers in the northern and southern hemispheres of the Sun in the current 24th cycle with the time of polar magnetic field reversal in the corresponding hemisphere is investigated. It was obtained that: – The change of the sign of the polar magnetic field at the southern pole occurs almost a year later than in the north. – The polar magnetic field reversals do not coincide with the maximum activity in each of the hemispheres. In the northern hemisphere, the activity maximum was observed almost one and a half years earlier than the first polar field reversal and two and a half years earlier than the third or final one. In the southern hemisphere, the activity maximum was observed almost a year earlier from the change of the field sign at the pole. – The maximum of the 24th cycle almost coincides with the time of the change of the sign of the magnetic field at the northern pole. – In each of the hemispheres, the change in the sign of a magnetic field in the polar zone above 55 degrees occurred almost two years earlier than the final polar field reversal. The second and third changes of the sign of the total field in the polar zone above 55 degrees occurred shortly after the corresponding polar field reversal. – In the northern hemisphere, the polar field reversals occur at the time of maximum values of the inclination of the heliospheric current sheet, and in the south – almost two years after the maximum inclination of the HCS. – Three-fold polar field reversal at the northern pole occurs at small values of polar magnetic field measured at the Wilcox Solar Observatory while single reversal at the southern pole occurs at sufficiently high value of the corresponding measured polar field.
Key words
Sun’s polar magnetic field, solar cycle
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