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Astron. Astrophys. 339, 880-886 (1998)
Latitudinal distribution of photospheric current helicity and solar activities
Hongqi Zhang and
Shudong Bao
Beijing Astronomical Observatory, Chinese Academy of
Sciences, Beijing 100080, P.R. China
Received 8 October 1997 / Accepted 24 April 1998
Abstract
In this paper, we analyze the latitudinal distribution of the
photospheric current helicity for 422 active regions, including most
of the large ones observed in the last ten years. Observations show
that most active regions in the northern hemisphere have negative
helicities and in the southern hemisphere have positive ones. The
negative maximum values of current helicity occurred in 1989 and 1991,
while those positive around 1992. It is evident that the observational
current helicity of active regions is normally brought up by emerging
magnetic flux from the subatmosphere and probably acted by the moving
mass. The result observed shows that less than 20
![[FORMULA]](img1.gif)
of active regions have the sign opposite to that
of most ones in the same hemisphere. These reversed sign regions of
the current helicity are obviously related to abnormal distribution of
the vector magnetic field in the active regions, due to emergence of
new magnetic flux of opposite polarities.
Key words: Sun:
activity 
Sun: magnetic
fields
Sun: photosphere
This article contains no SIMBAD objects.
Contents
- 1. Introduction
- 2. Definition of current helicity
- 3. Latitudinal variation of current helicity
- 4. Current helicity and magnetic shear in active regions
- 5. Discussion and results
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: October 22, 1998
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