Authors: Johnathan R. Stauffer (NRC Research Associate/NRL), Mark G. Linton (NRL), Peter W. Schuck (NASA/Goddard)

While electrical currents are thought to play an important role in the generation of solar flares and coronal mass ejections (CME’s), they remain difficult to directly study as only the normal current density, J_r, can be calculated directly from observations. Indirect information about the 3D structure of atmospheric currents can be obtained by studying the magnetic fields they generate in the solar photosphere, but are often obscured by the stronger field signatures generated by currents in the solar convection zone. These contributions to the solar surface magnetic field (as well as the contribution from the surface-threading current J_r) can be separated through the application of Gauss’s separation algorithm, allowing for more detailed study of coronal current systems in the lead-up to solar flares.

We demonstrate the utility of this method by applying Carl’s Indirect Coronal Current Imager (CICCI; a publicly available implementation of Gauss’s separation method) to observations of NOAA Active Region 11158, which hosted a number of CME-productive flares between 2/13 and 2/18/2011. By combining CICCI diagnostics of the surface-threading (i.e., radial) and coronal current distributions, we observe the emergence of several twisted flux ropes prior to the start of flaring activity. Application of this technique to a larger selection of active regions shows that significant pre-flare evolution can be seen in most cases, suggesting that CICCI can be a powerful tool for studying the role of currents in solar flare onset.