COMPARISON BETWEEN PROBABILITY DENSITY FUNCTIONS OF VERTICAL ELECTRIC CURRENT IN SOLAR ACTIVE REGIONS BASED ON HMI/SDO AND SOT/HINODE DATA

Studying electric currents in solar active regions (AR) is an essential step in understanding solar activity in general and solar flares in particular. In this paper, we compare probability density functions of vertical electric current PDF(j_z ) in several active regions, using HMI/SDO and SOT/Hinode photospheric magnetic field data. We have established that in the AR parts which contain current structures with current density above the noise level (j_z >9·10³ statampere/cm²) these functions are nearly identical. The main difference in PDFs for low (noise) j_z≾9·10³ statampere/cm² is due to differences in sensitivity of these two instruments. We have also found that the criterion of pixel selection from magnetic field strength is inapplicable, and the similarity between PDFs is determined by high j_z. For all PDF(j_z ) under study we have calculated the power law exponent of the PDF tail for the two instruments, which coincide within their errors for the current structures with current values above noise level. Thus there is no significant difference as to which instrument is used for analyzing probability density functions in high current parts of ARs where flares are localized.