Determining the Energy Transport Through the Photosphere into Corona with HMI

Abstract:

The underlying source of all solar activity, from the largest explosive solar eruptive event to the quasi-steady radiation from quiet regions is the transport of free magnetic energy into the chromosphere and corona through the photosphere. There are two mechanisms for this transport, the emergence of magnetic field and accompanying electric currents, and the stressing of pre-emerged chromosphere and coronal field by photospheric flows. Consequently, if we are ever to understand solar activity it is essential that the flow of energy be measured accurately. In principle, this can be estimated from the high spatial and temporal resolution vector magnetograms obtained by HMI on SDO. However, due to the artifacts introduced by the orbital motions of SDO convolved with the finite-sampling of the relevant polarizations, the data cannot be used for measuring the energy flux or helicity flux accurately. We present recent work on the first successful attempt to remove the orbital artifacts. We describe the procedure, which consists of correcting each pixel separately for its bias and gain. We show results for before and after our artifact removal procedures. The method is being prepared for community use through the SDO pipeline. We discuss the application of our methods to analyzing active regions both with and without major eruptions. This work was supported by the NASA LWS and R&A Programs.