Current Helicity and Twist as Two Indicators of The Mirror Asymmetry of   solar Magnetic Fields
  A comparison between the two tracers of magnetic field mirror asymmetry in solar active regions, twist and current helicity, is presented. It is shown that for individual active regions these tracers do not possess visible similarity while averaging by time over the solar cycle, or by latitude, reveals similarities in their behaviour. The main property of the dataset is anti-symmetry over the solar equator. Considering the evolution of helical properties over the solar cycle we find signatures of a possible sign change at the beginning of the cycle, though more systematic observational data are required for a definite confirmation. We discuss the role of both tracers in the context of the solar dynamo theory. 
D.D. Sokoloff, H. Zhang, K. Kuzanyan, V.N. Obridko, D.N. Tomin, V.N.   Tutubalin