Authors: A.A. Norton, J.D. Graham, B.W. Lites, H. Socas-Navarro, S. Tomczyk
Affiliation: National Center for Atmospheric Research, High Altitude Observatory
In the interest of obtaining full disk vector magnetic field measurements at high spatial and temporal resolution with the Helioseismic Magnetic Imager (HMI), we investigate the process of filtergraph polarimetric observations and inversion techniques. Accuracies for field strengths, inclination angles and flux densities are determined using a Levenberg-Marquardt least-squares minimization algorithm with simulated and observed stokes profiles. Number of wavelengths sampled and non-simultaneity of observation sequences are investigated. Retrieving the magnetic field vector from the polarization measurements requires the use of an inversion algorithm that is capable of handling the high rate of data that will be obtained by HMI. A novel technique, based on the application of artificial neural networks, allows an unprecedented rate of ~1,000 sets of profiles inverted per second.