Vertical Electric Currents in Active Regions: Calculation Methods and Relation to the Flare Index

Abstract

In the scope of the performed work, two problems are solved. The first is the analysis of two existing methods for calculating vertical electric currents, differential and integral. The integral method has some advantages compared to the differential method. Among them, one can mention there is no need to differentiate the magnetic field and a good smoothing of noises without losing significant information about the current structures. The integral method of calculating vertical currents has been tested for the NOAA AR 11158 using the data of two instruments, the Helioseismic and Magnetic Imager of the Solar Dynamics Observatory (HMI/SDO) spacecraft and the Solar Optical Telescope of the Hinode satellite (SOT/Hinode). There was a good correlation between the calculated data (the coefficient of correlation k = 0.77). This result indicates a sufficient reliability of data on currents calculated by the integral method, regardless of the observation instrument. In the second part of the work, we analyze the data on the relation between the flare activity of groups of spots and the magnitude of the vertical current in them. A direct dependence between these quantities has been established: the greater the mean squared vertical current density, the higher the flare activity of the region (the coefficient of correlation k₁ = 0.91).