K. Otsuji
We have carried out a statistical study on the current helicity of solar active regions observed with the Spectro-Polarimeter (SP) of Hinode Solar Optical Telescope (SOT). We used SOT-SP data of 558 vector magnetograms of a total of 80 active regions obtained from 2006 to 2012. This period covers from the end of the solar cycle-23 to the middle of cycle-24. To avoid the projection effect, we excluded the data obtained near the solar limb. We divided the area of an active region into weak (<300 G) and strong (300~1000 G) field ranges to compare the contributions from different field strengths. The result of weak field area shows the same distribution of current helicity as the preceding studies. On the other hand, the strong field area shows the opposite dependency, i.e. positive current helicity in the northern hemisphere and negative in the south. This opposite natures may come from the difference of the origins of strong and weak magnetic fields.
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