Measurements of Free Magnetic Energy Flux Across the Photosphere

Solar flares and CMEs are thought to be powered by free energy in the coronal magnetic field. Several theoretical models make testable predictions about how this free magnetic energy enters the corona through the photosphere (e.g., cancellation, or shear along polarity inversion lines). Further, some observers have suggested particular mechanisms (e.g., rotating sunspots) might play an important role in transporting free magnetic energy into the corona. In addition, the flux of free energy might be correlated with local coronal heating, which could lead to EUV and/or X-ray emission. Here, we present formalism that allows determination of the flux density of free magnetic energy from a time series of vector magnetograms and results derived from velocity inversion techniques (e.g., local correlation tracking, or inductive local correlation tracking). We then apply this approach to time series of vector magnetograms, and compare: 1) the locations of measured free energy flux with the predictions of both modelers and observers; 2) our integrated free energy flux with typical flare and CME energies; and 3) Yohkoh SXT images of the corona above these active regions.