The analysis and exploration of auroral dynamics are very significant for studying auroral mechanisms.This paper proposes a method based on auroral dynamic processes for detecting auroral events automatically.We first obtained the motion fields using the multiscale fluid flow estimator.Then,the auroral video frame sequence was represented by the spatiotemporal statistics of local motion vectors.Finally,automatic auroral event detection was achieved.The experimental results show that our methods could detect the required auroral events effectively and accurately,and that the detections were independent on any specific auroral event.The proposed method makes it feasible to statistically analyze a large number of continuous observations based on the auroral dynamic process.
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 poleward moving auroral forms (PMAFs) and the associated plasma features in the polar ionosphere under different interplanetary magnetic field (IMF) 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 precipitate 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 latitudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection.
