MHD simulation of rapid change of photospheric magnetic field during solar eruption caused by magnetic reconnection

It has been well observed that the horizontal component of magnetic field at photosphere changes rapidly and irreversibly after solar eruptions. Specifically, near polarity inversion line increases substantially, while center decreases. Such a phenomenon is considered as dynamic feedback from corona to photosphere, but underlying mechanism remains in debate. Here based on recent magnetohydrodynamics (MHD) simulation homologous eruptions initiated by reconnection, we analyzed rapid field, inclination angle, Lorentz force derivative variation field. The reproduces pattern evolution during agreement with typical observations. Our analysis suggests physical reasons for this phenomenon: 1) becomes more flares due compression downward outflow flare accordingly angle decreases increases; 2) polarities become vertical mainly expansion effect velocity divergence term, result upward increase.