Cycle dependence of the longitudinal-latitudinal sunspot motion correlations

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• 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.

The Greenwich Photo-heliographic Results (1874 – 1976): Summary of the Observations, Applications, Datasets, Definitions and Errors

“…Ivanov (2007) studied active longitudes in terms of their structure, dynamics and rotation for Solar Cycles 12 -23, while Dikpati (2008) predicted Solar Cycle 24 using various dynamo-based tools. The cycle dependence of the longitudinal-latitudinal sunspot motion correlations has been investigated by Muraközy and Ludmány (2008). Tlatov (2009) discussed the prediction of the amplitude of solar activity cycles, using the recorded number of sunspot groups, and Miletskii and Ivanov (2009) studied the latitude characteristics of the sunspot formation zone and the 11-year solar activity cycle.…”