Latitudinal motions of the aurora during substorms
Latitudinal motions of the aurora during substorms
复制标题
DOI：
10.1029/ja092ia05p04565
复制
发表时间：
1987-05
影响因子：
--
通讯作者：
J. Craven;L. Frank
中科院分区：
文献类型：
--
作者：
J. Craven;L. Frank
Sequences of auroral images obtained with Dynamics Explorer 1 are used to investigate latitudinal motions of the aurora in substorms. Average speeds of poleward motion are about 230 m/s near local midnight for two isolated, small substorms and about 1000 m/s during an intensification within a previously active auroral oval. The speed of poleward expansion measured at about 6-min temporal resolution can differ greatly from the average speed because of the episodic development of substorms. This poleward motion may be influenced by the sign of the z component of the interplanetary magnetic field. Recovery of the high-latitude boundary of the aurora to presubstorm latitudes is first observed in the postmidnight sector. In the premidnight sector the discrete aurora can become stationary for a period of time or even continue further poleward before a retreat to lower latitudes begins. For these substorms, the expansion and recovery phases are not separated by an about 5-deg poleward leap of the aurora. During the recovery phase, a prominent decrease in luminosities is first observed at intermediate latitudes within the auroral distribution. The region is bounded at higher latitudes by the discrete aurora and at lower latitudes by bright diffuse aurora. Given that magnetic fieldmore » lines threading these auroral distributions map to the plasma sheet boundary layer and to the central plasma sheet, respectively, magnetic field lines at the intermediate auroral latitudes then map to the plasma sheet at distances of some what 22 R/sub E/.« less
