Cycle dependence of the longitudinal-latitudinal sunspot motion correlations

TL;DR

This study investigates the latitudinal dependence of sunspot motion correlations over time, revealing a Coriolis-like distribution that varies with the solar cycle and shows unexpected distortions at cycle maxima.

Contribution

It provides the first detailed analysis of the temporal evolution of sunspot motion correlations across latitudes over multiple solar cycles.

Findings

Sunspot motion correlations exhibit a latitudinal distribution consistent with the Coriolis effect.

Cycle maximum shows unexpected distortions in the correlation distribution.

Weakening of the Coriolis pattern remains unexplained, with potential links to magnetic field reversals.

Abstract

aims: It is well known that the azimuthal and meridional shifts of sunspots are correlated and that the correlation exhibits a latitudinal distribution, which is expected due to the Coriolis effect. We study the temporal behaviour of this latitudinal distribution. methods: We analyze the daily positions of sunspot groups, provided by the Debrecen Photoheliographic Data and the Greenwich Photoheliographic Results and correlation values, which were mapped in 5 deg latitudinal bins. The latitudinal distributions were examined for each year. results: We derive a sunspot-motion correlation that exhibits a Coriolis-type latitudinal distribution on long timescales, which are typical for the yearly distributions; at cycle maximum, however, unexpected distortions can occur. conclusions: The causes of the weakening of the Coriolis-pattern remain unclear. Possible relations of the phenomenon to the Gnevyshev-gap, the polarity reversal of the main magnetic field, and some mid-period fluctuations are discussed.