Cycle dependence of the longitudinal-latitudinal sunspot motion correlations

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 posit...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2008-08, Vol.486 (3), p.1003-1007
Main Authors: Murakoezy, J, Ludmany, A
Format: Article
Language:English
Subjects:
Astronomy
Earth, ocean, space
Exact sciences and technology
Sun: activity
Sun: rotation
sunspots
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Summary: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 $5^\circ$ 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.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361:20078456