Rapid Spatiotemporal Evolution of Vertical Electric Currents during an X-class Flare

In this paper, we present a detailed analysis of the spatiotemporal evolution of photospheric vertical electric currents (VECs) during an X1.1 flare (SOL2013-11-10T05:08). The VEC on the solar surface is calculated using the 135 s high-temporal-resolution vector magnetograms obtained from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. In the region, a highly sheared magnetic channel that is also a polarity inversion line (PIL) divides the region into two parts. The spatial configuration of VEC ribbons is always conjugate footprints, and it takes the form of a sigmoid along two sides of the PIL at the beginning of the flare. The temporal evolution of the VECs shows a rapid enhancement associated with the impulsive phase of the flare, and mean horizontal fields in this region show similar temporal behavior. The most prominent enhancement of VECs not only shows up along the two sides of the enhancement B h but also spreads outward along the PILs. The VECs in positive and negative fields have an initial separation motion and are followed by an apparent approaching motion. In contrast, the flaring loops and white-light flare ribbons have an initial contraction and later expansion motion. Our results show that the rapid change of magnetic fields related to flares has a predominant role in affecting the spatiotemporal evolution of VECs.