SOLARNET Conference: The Many Scales of the Magnetic Sun

The build-up of magnetic energy during flux emergence, which powers flares and coronal mass ejections (CME), requires the presence of significant amounts of volume electric currents. Measuring these electric currents requires knowledge of the magnetic field vector in three dimensions in the solar atmosphere. However, systematic high-quality spectropolarimetric observations are constrained at the photosphere. Thus, only the vertical component of the electric current density, Jz, can be routinely calculated by means of differentiation of the photospheric magnetic field vector. In this work, a different method, relying on image segmentation and taking into account observational and numerical errors, is employed to determine the total unsigned non-neutralized (net) electric currents, INN,tot, injected to the corona. This quantity deviates from Jz and is more closely associated to the development of strongly sheared polarity inversion lines (PIL). It is found that INN,tot is at least one order of magnitude higher for flare productive active regions and its temporal evolution from emergence to decay exhibits intricate structure, owing to the interaction between opposite magnetic polarities and the formation of PILs. Further relevant quantities facilitate the distinction between imminent eruptive and confined major flares and they are strongly correlated with the kinematic characteristics of subsequent CMEs. These quantities are examined during the emergence and pre-eruptive evolution of active regions and their association with the magnetic complexity of active regions.