Modelling magnetic helicity flux through solar photosphere from ASO-S/FMG

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