Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar （ESR） and SuperDARN radars, we investigated the dayside pole- ward moving auroral forms （PMAFs） and the associated plasma features in the polar ionosphere under difibrent interplanetary magnetic field （1MF） conditions, between 0900 and 1010 UT on 22 December 2003. Simultaneous optical and ESR observations revealed that all PMAFs were clearly associated with pulsed particle precipitations. During northward IMF, particles can precipi- tate into lower altitudes and reach the ionospheric E-region, and there is a reverse convection cell associated with these PMAFs. This cell is one of the typical signatures of the dayside high-latitude （lobe） reconnection in the polar ionosphere. These results indicate that the PMAFs were associated with the high-latitude reconnection. During southward IMF, the PMAFs show larger lati- tudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection.
We present observations of a duskside shock aurora occurred on 21 April 2001 by the SuperDARN radar at Syowa Station and the all-sky camera at Zhongshan Station （ZHS） in Antarctica when the radar was operated in fast-scan mode covering the ZHS region. With the two independent data sets, we examine ionospheric plasma convection and aurora arising from a sudden impulse （SI） event associated with an interplanetary shock. During the transient shock compression, the aurora was quiescent without any optical emission at the preliminary impulse of the SI. About 7 min later, a new thin auroral arc with brighter emissions and a lifetime of -14 rain expanded westward from the region above ZHS during the main impulse of the SI. SuperDARN radar line-of-sight measurements showed periodical oscillation in the flow direction with ultra-low-frequency waves having a period of -8 min during the shock compression. We suggest that downward field-aligned current during the preliminary impulse stage of the SI was the main driver of the first plasma flow reversal, and the subsequent new discrete auroral arc may be associated with field-aligned acceleration in the region of the main impulse related upward field-aligned currents. The ground magnetometer observations suggest that the oscillation of the ionospheric convection on the duskside was associated with field line resonance activity.
LIU JianjunHU HongqiaoHAN DeshengLIU YonghuaZHANG QingheAkira S Yukimatu
