Структура и динамика полярных токовых систем : материалы международного симпозиума «Полярные геомагнитные явления», 25-31 мая, Суздаль, СССР / Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т. – Апатиты : [б. и.], 1988.

OBSERVATIONS. The HILAT spacecraft was launched on 27 June 1983 into a 800 km near circular orbit, with an inclination of 82.2°. The in-situ plasma data examined in this paper was aquired from the magnetic field experiment, the energetic electron spectrometer, Ion Drift Meter (IDM) and Retarding Potential Analyzer (RPA). Remote imaging of the aurora was provided by a vacuum ultraviolet (VUV) auroral imager mapper (AIM). On 17 July 1983 at approximately 10:25 UT, HILAT crossed the 2400-0600 MLT sector of the northern hemisphere auroral oval along a southbound trajec tory. The three hour Kp index for this period was 4+ and the sum of Kp for the day was 32-. Under these disturbed magnetic conditions, the auroral imager о detected emissions from the sunlit ionosphere at 1356 A throughout the sector that extended from about 71° MLAT (magnetic latitude) down to about 62° MLAT. 300 17 . 07.1983 Doiu/n Я = 13f6 о Fig. 1. A VUV image at 1356 A generated by the AIM showing the early morning sector of the auroral oval. Note the undulations on the poleward edge at about 68° magnetic latitude. The dashed line indicates the terminator at 110 km while the solid line in the center represents the satellite track. Figure 1 is the image formed by concatenating consecutive scan lines from the AIM spectrometer and correcting for angular dispersion. Latitude and longitude grids are in geomagnetic coordinates and 0600 MLT is indicated as dawn. The dashed line corresponds to the locationj6f the terminator at 110 km with daylight on the right, while the solid line in the center represents the spacecraft track. The image thus generated clearly depicts a portion of the diffuse aurora that is marked by large-scale undulations along its poleward edge at about 65° MLAT. An intense longitudinally limited region of emission is located in the center of the image directly beneath the satellite orbital path and at the high latitude rim of the diffuse aurora. Just poleward of this region, the imager detected at least two less intense bands of emission indicated by the arrows. These bands extend outward into the polar cap region from the corrugations formed in the poleward edge of the diffuse aurora. The relationships between the VUV emission regions and the associated m-situ electric and magnetic fields is readily apparent in Figure 2. Here, we have expanded the central portion of the image to enhance the fainter narrow bands of emission poleward of the bright arc-like feature seen at the 49