Hemispheric helicity sign rule and its solar cycle dependence

M. Zhang1*, J. Hao1 and C. Y. Wang2
1Key Laboratory of Solar Activity, National Astronomical Observatory, Chinese Academy of Sciences
2National Center for Space Weather Monitoring and Warning,Chinese Meteorological Administration

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Abstract

We take two approaches to study whether the hemispheric helicity sign rule is preserved over a whole solar cycle or not. We find that, for global-scale magnetic fields on the photosphere, the hemispheric helicity sign rule is evident in fields up to 60 degrees in latitude and shows no solar-cycle dependent. For active regions observed by SP/Hinode, the hemispheric helicity sign rule is preserved in the ascending phase of solar cycle 24, but not in the descending phase of solar cycle 23.

Fig. 1 Fig. 2


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Keywords : Sun: magnetic topology – Sun: photosphere – sunspots