Electric current helicity in 40 active regions in the maximum of solar cycle 22

V. I. Abramenko, Tongjiang Wang, V. B. Yurchishin

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Abstract

Using vector magnetograms of 40 active regions (ARs) of the maximum of solar cycle 22, we calculated the imbalance ρh (over the AR area) of the current helicity hc ≡ Bz(▽ × B)z in the photosphere. In 82.5% of the cases the predominant current helicity was negative (ρh < 0) in the northern hemisphere and positive (ρh > 0) in the southern hemisphere. Thus, the predominance of counter-clockwise (clockwise) vortices in the northern (southern) hemisphere seems to be valid not only for unipolar spots with obvious vortex structure (Hale, 1927; Richardson, 1941; McIntosh, 1979; Ding, Hong, and Wang, 1987) but also for ARs of different types. The forces of rotation of the Sun (Coriolis force and/or differential rotation) seem to take effect in the twisting of various magnetic structures.

Original languageEnglish (US)
Pages (from-to)291-296
Number of pages6
JournalSolar Physics
Volume174
Issue number1-2
DOIs
StatePublished - 1997

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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