Cyclic changes of the photospheric magnetic field polarity

TL;DR

This study analyzes solar photospheric magnetic field data from 1978 to 2016, revealing cyclic polarity changes with a period of 1-3 years, linked to quasi-biennial variations, through empirical orthogonal function analysis.

Contribution

It identifies and characterizes cyclic polarity changes in the Sun's magnetic field using long-term synoptic maps and EOF analysis, highlighting a possible connection to quasi-biennial oscillations.

Findings

Inclined bands of magnetic polarity drift towards the poles.

Polarity changes exhibit a 1-3 year cycle.

Connection to quasi-biennial variation suggested.

Abstract

The distribution of magnetic fields of positive and negative polarities over the surface of the Sun was studied. Synoptic maps of the photospheric magnetic field (NSO Kitt Peak, 1978--2016) were used for the analysis. In the time-latitude diagram for weak magnetic fields ($B \leq 5 G$), inclined bands are clearly visible, indicating the alternating dominance of magnetic fields with positive or negative polarity drifting towards the poles of the Sun. Analysis of the time-latitude diagram using the method of empirical orthogonal functions (EOF) made it possible to establish a cyclic change in the polarity of magnetic field flows with a period of 1-3 years, which indicates a possible connection with quasi biennial variation. Similar period values are obtained by averaging over the latitude of the time-latitude diagram