Comparison of Relative Magnetic Helicity Flux Calculation Results Based on the Line-of-Sight Magnetograms of ASO-S/FMG and SDO/HMI

Abstract

Magnetic helicity is a key geometrical parameter to describe the structure and evolution of solar coronal magnetic fields. The accumulation of magnetic helicity is correlated with the nonpotential magnetic field energy, which is released in the solar eruptions. Moreover, the relative magnetic helicity fluxes can be estimated only relying on the line-of-sight magnetic field (e.g. Démoulin and Berger 2003). The payload Full-disk MagnetoGraph (FMG) on the Advanced Space-based Solar Observatory (ASO-S) currently has been supplying the continuous evolution of line-of-sight magnetograms for the solar active regions, which can be used to estimate the magnetic helicity flux. In this study, we use eight-hour line-of-sight magnetograms of NOAA 13273, at which the Sun–Earth direction speed of the satellite is zero to avoid the oscillation of the magnetic field caused by the Doppler effect on polarization measurements. We obtain the helicity flux by applying fast Fourier transform (FFT) and local correlation tracking (LCT) methods to obtain the horizontal vector potential field and the motions of the line-of-sight polarities. We also compare the helicity flux derived using data from the Heliosesmic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) and the same method. It is found that the flux has the same sign and the correlation between measurements is 0.98. The difference of the absolute magnetic helicity normalized to the magnetic flux is less than 4%. This comparison demonstrates the reliability of ASO-S/FMG data and that it can be reliably used in future studies.