Comparison of force-free coronal magnetic field modeling using vector fields from Hinode and Solar Dynamics Observatory

TL;DR

This study compares nonlinear force-free coronal magnetic field models derived from vector magnetic data obtained by Hinode and SDO/HMI, analyzing how instrument differences and resolution affect model outcomes.

Contribution

It provides a detailed comparison of magnetic field models from different instruments and resolutions, highlighting the impact on magnetic energy estimates and topology.

Findings

SP data yields stronger magnetic fields and higher magnetic energy.

Force-free compatibility verified between HMI and SP boundary data.

Differences between models are mainly due to instrument and resolution variations.

Abstract

Photospheric magnetic vector maps from two different instruments are used to model the nonlinear force-free coronal magnetic field above an active region. We use vector maps inferred from polarization measurements of the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (HMI) and the Solar Optical Telescope Spectropolarimeter (SP) aboard Hinode. Besides basing our model calculations on HMI data, we use both, SP data of original resolution and scaled down to the resolution of HMI. This allows us to compare the model results based on data from different instruments and to investigate how a binning of high-resolution data effects the model outcome. The resulting 3D magnetic fields are compared in terms of magnetic energy content and magnetic topology. We find stronger magnetic fields in the SP data, translating into a higher total magnetic energy of the SP models. The net Lorentz forces of the HMI and SP lower boundaries verify their force-free compatibility. We find substantial differences in the absolute estimates of the magnetic field energy but similar relative estimates, e.g., the fraction of excess energy and of the flux shared by distinct areas. The location and extension of neighboring connectivity domains differs and the SP model fields tend to be higher and more vertical. Hence, conclusions about the magnetic connectivity based on force-free field models are to be drawn with caution. We find that the deviations of the model solution when based on the lower-resolution SP data are small compared to the differences of the solutions based on data from different instruments.