The horizontal and vertical electric currents in three solar active regions and their relations with flares

Abstract

In this work, systematic calculations are carried out for the distributions of electric currents in three super-active regions (large δ-type spot groups) NOAA 5395, 6659 and 6891. A method of computation published by us is for the first time applied to reveal the distribution of horizontal currents in active regions. The relation between currents and flare kernels may be divided into two kinds, i.e. close correlation and quasi-close correlation. Our statistical results are as follows: (1) For the vertical and horizontal currents, the rates of close correlation are, respectively, 29% and 10%, and those of quasi-correlation are 50% and 30%. (2) Some flare kernels are correlated with both kinds of current, but most flare kernels are correlated with only one kind. (3) There is a small percentage (about 6%) of flare kernels that are not correlated with either kind of current. (4) The two kinds of current supplement each other, and this may be noted in flare forecast. Our analysis also reveals that the places with strong shearing of magnetic field correspond to intense vertical currents and the places with large gradients of magnetic field in the vicinity of magnetic neutral line correspond to intense horizontal currents.