Yang Liu

TL;DR: The Helioseismic and Magnetic Imager (HMI) instrument and investigation as a part of the NASA Solar Dynamics Observatory (SDO) is designed to study convection-zone dynamics and the solar dynamo, the origin and evolution of sunspots, active regions, and complexes of activity, the sources and drivers of solar magnetic activity and disturbances as mentioned in this paper.

TL;DR: The Helioseismic and Magnetic Imager (HMI) as discussed by the authors was designed to measure the Doppler shift, intensity, and vector magnetic field at the solar photosphere using the 6173 A FeI absorption line.

TL;DR: In this article, the Helioseismic and Magnetic Imager (HMI) active region patches (HARPs) are used to track the location and shape of magnetic regions throughout their lifetime.

TL;DR: The SHARP data series as mentioned in this paper provides maps in patches that encompass automatically tracked magnetic concentrations for their entire lifetime, including the photospheric vector magnetic field and its uncertainty, along with Doppler velocity, continuum intensity, and line-of-sight magnetic field.

TL;DR: In this paper, the authors compare six algorithms for the computation of nonlinear force-free (NLFF) magnetic fields (including optimization, magnetofrictional, Grad-Rubin based, and Green's function-based methods).