A brief report on statistical study of net electric current in solar active regions with longitudinal fields of opposite polarity

摘要

Dynamic processes occurring in solar active regions are dominated by thesolar magnetic field. As of now, observations using a solar magnetograph havesupplied us with the vector components of a solar photospheric magnetic field.The two transverse components of a photospheric magnetic field allow us tocompute the amount of electric current. We found that the electric current inareas with positive (negative) polarity due to the longitudinal magnetic fieldhave both positive and negative signs in an active region, however, the netcurrent is found to be an order-of-magnitude less than the mean absolutemagnitude and has a preferred sign. In particular, we have statistically foundthat there is a systematic net electric current from areas with negative(positive) polarity to areas with positive (negative) polarity in solar activeregions in the northern (southern) hemisphere, but during the solar minimumthis tendency is reversed over time at some latitudes. The result indicatesthat there is weak net electric current in areas of solar active regions withopposite polarity, thus providing further details about the hemispherichelicity rule found in a series of previous studies.