Abstract
Using magnetometer data acquired by geosynchronous satellite and all-sky images from a ground optical station in the conjugate area, we show propagation of aurora surge repeating in a thin and narrow aurora arc at the poleward boundary of the aurora zone. The surge repetition correlated with the Pi2s at the geosynchronous altitudes. One-to-one conjunctions of the surge and Pi2 pulse were not always observed. The westward or eastward propagation directions of the surge corresponded to the clockwise or counterclockwise wave polarizations in the equatorial plane. Propagation velocities of the poleward surge were in the range of 0.2–0.5°/s or 12–30km/s at 100km altitudes. We discuss the propagating surge at poleward boundary in conjunction with bi-directional flows in the first 10min intervals of Pi2 onset that were inferred by Saka et al. (2010) from the Pi2 epoch analyses of magnetometer data at geosynchronous altitudes.
Published Version
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