Alexander Mordvinov

NameAlexander Mordvinov
AffiliationISTP SB RAS, Russia
TitleMultiple reversals of the Sun's polar-fields and their physical causes
AuthorsA.V Mordvinov, B.B. Karak, D. Banerjee, S. Chatterjee, E.M.Golubeva, A.I. Khlystova
AbstractLong-term uniform observations for the past 100 years as recorded at the Kodaikanal Solar Observatory (KoSO) provide a wealth of information on solar activity. We develop a method for the reconstruction of the solar magnetic flux using the synoptic observations of the Sun’s emission in the Ca II K and Hα lines from KoSO. The reconstruction is based on the facts that the Ca II K intensity correlates well with the unsigned flux, while the sign of the flux is derived from the corresponding Hα map which provides the information of the dominant polarities. Time-latitude analysis of the reconstructed magnetic flux depicts an overall view of magnetic field evolution: emergent magnetic flux, its further transformations with the formation of unipolar magnetic regions and remnant flux surges in Cycles 15-19. We identify the critical surges of following polarities which result in the regular reversals of the Sun's polar-fields. The poleward transport of predominantly following polarities contributed much of the polar flux and led to polar field reversals. Multiple reversals of the Sun’s polar-fields were identified in Cycles 16 and 19. The decay of non-Joy and anti-Hale active regions results in remnant flux surges that disturb the usual order in magnetic flux transport and sometimes lead to multiple changes of the dominant magnetic polarities at the Sun’s poles. We found also the remnant flux transport between adjacent 11-year cycles. These surges indicate a physical connection of subsequent solar cycles. We further analyze evolution of the Sun’s polar-fields in cycles 21-24. The time-latitudinal analysis of high-resolution synoptic maps makes it possible to identify surges of leading and following polarities in relation to their sources. All these analyses improve our understanding of cyclic patterns that demonstrate global reorganization of the magnetic flux and the polar field buildup.