抄録
This paper reports latitudinal and longitudinal movements of four low-latitude auroras observed by a meridian scanning photometer and an all-sky TV camera at Moshiri and Rikubetsu (L = 1.6) in Japan during magnetic storms. It is observationally found that the low-latitude auroras occur in the region of L ∼ 2 even during moderate magnetic storms. The auroras which are characterized by 6300-Å emissions of several kR are also found to take place associated with magnetospheric substorm activity during the maximum phase of magnetic storms. The auroras and associated current systems inferred from ground magnetic field fluctuations tend to expand from midnight toward both the dawnside and the duskside. It is suggested that the observed low-latitude auroras are excited by precipitating low-energy electrons originated in the plasmasphere. We discuss generation mechanisms of these electrons based on the observations.
