The rotational motions of the photospheric magnetic flux play a role in magnetic twist transportation between the corona and the solar interior. Using observations from the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory (SDO), we found one counterclockwise and two clockwise vortex flows on the photosphere in the NOAA active region 12371 during the flare SOL2015-06-22T18:23 (M6.5). The counterclockwise vortex was located on the footpoint of the erupting hot channels observed by the Atmospheric Imaging Assembly (AIA) Telescope on board SDO. The two clockwise vortices resided on either side of the polarity inversion line. At these vortices, the impulsive and irreversible change in the photospheric vector magnetic field were detected. The resulting change in the photospheric Lorentz force provides a torque in each vortex, which has the same direction with each vortex. A magnetic field extrapolation model shows that the coronal field starting from the two clockwise vortices suffered significant shrinkage during the changeover period of the photospheric field. Moreover, some of the modeled field rooted in the counterclockwise vortex displays a pronounced expansion during the flare. These results suggest that the clockwise vortices could result from the contraction of the magnetic field lines during the flare, while the counterclockwise vortex may be attributed to the expansion of the eruptive flux rope as observed in the AIA images.

Context. The Full-disk Vector MagnetoGraph (FMG) is one of the three payloads on the Advanced Space-based Solar Observatory (ASO-S). The FMG is set to observe the full disk vector magnetic field at a single wavelength point. The magnetograph in orbit will encounter the wavelength shift problem caused by the Doppler effect in the magnetic field, which mainly comes from the Sun's rotation velocity and the satellite-sun relative velocity. Aims. We look to use neural networks for single-wavelength calibration to solve the wavelength shift problem. Methods. We used the existing data from the Helioseismic and Magnetic Imager (HMI) on the Solar Dynamics Observatory (SDO).To simulate plausible single-wavelength observations, we used the Stokes polarization image from the HMI at a single wavelength point. We also input the satellite orbital velocity given by the HMI data file and the solar rotation velocity to the network. We developed a set of data preprocessing methods before entering the network and we trained the network to get the calibration model. Results. By analyzing and comparing the prediction of the neural network with the target magnetogram, we believe that our network model has learned a single-wavelength full-disk calibration model. The mean absolute error (MAE) of the longitudinal field and the transverse field of the full disk are 3.68 Gauss and 28.08 Gauss, respectively. The MAE error of the azimuth angle of pixels above 300 Gauss is 12.29 degrees.