On the Latitude Distribution of the Polar Magnetic Flux as Observed by SOLIS-VSM

TL;DR

This study analyzes SOLIS-VSM magnetograms to understand how magnetic flux elements are distributed across solar polar latitudes, revealing a decrease near the poles and differences based on flux element size, which impacts solar cycle and wind studies.

Contribution

It provides detailed observations of magnetic flux distribution in polar regions, highlighting size-dependent variations and their implications for solar magnetic and wind phenomena.

Findings

Magnetic flux density is relatively flat up to 70-75° latitude and then decreases.

Larger flux elements show a more pronounced decrease near the poles.

Smaller flux features are more uniformly distributed across polar latitudes.

Abstract

Magnetograms from the Vector SpectroMagnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) project are utilized to study the latitude distribution of magnetic flux elements as a function of latitude in the polar solar caps. We find that the density distribution of the magnetic flux normalized by the surface of the polar cap and averaged over months decreases close to the solar poles. This trend is more pronounced when considering only flux elements with relatively large size. The flux density of the latter is relatively flat from the edge of the polar cap up to latitudes of 70$^\circ$--75$^\circ$ and decreases significantly to the solar pole. The density of smaller flux features is more uniformly distributed although the decrease is still present but less pronounced. This result is important in studying meridional flows that bring the magnetic flux from lower to higher solar latitudes resulting in the solar cycle reversal. The results are also of importance in studying polar structures contributing to the fast solar wind, such as polar plumes.