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.

29. 1.1984 UT increasing depression at Great Whale River in the midnight sector of the auroral zone may be signatures of the growth phase of the following substorm activity. A modest substorm onset is observed in the midnight sector at 0612 UT, followed by the onset of a larger disturbance at 0708 UT. OBSERVATIONS. Precipitating low energy electron data were obtained by electrosta tic analyzers aboard DMSP satellites nos. 7540 and 8541 along 840 km sun-synchronous circular polar orbits in the dawn-dusk and noon-midnight sectors. Pig.3 shows a typical electron precipitation profile along the dawn-dusk meridian during a very quiet interval (Kp = Oo). Prom top to bottom the integral number flux, energy flux, and average energy of electrons are recorded along with the orbital information of the satellite (magnetic local time, MLT, correo- ted geomagnetic latitude, MLAT, and geogra phic latitude, CLAT). The satellite traver ses the electron precipitation region in the morning sector at about 0520 MLT from 0245 to 0249 UT, at which time it enters the polar cap. At about 1800 MLT it leaves the polar cap and traverses the evening electron precipitation region from 0254 to 0257 UT. The region of enhanced electron precipitation extends from 68°.8 to 82°.5 oorr.geom.lat. in the morning sector and from 71°.8 to 80°,6 in the evening sector. Also shown is the position of the transition boundary as defined by Makita et al.(1983). This boundary divides the region into two parts: a fairly uniform (continuous) hard precipitation region at lower latit'- udes and a more structured soft precipitation region at higher latitudes. In Fig.3 the transition takes place at ab, 74°.6 both in the morning and in the evening sectors. In the present study the polar cap boundary has been defined as the location where the electron number flux drops to a background level of Typically for magnetic quiet periods numerous spikes Pig. 2. Variation of the magnetic H-component in the noon ana midnight sectors of the oval near midnight at an equatorial station on Nov.29,1984. ab. 10^el (cm*" s ster)-1 MLT 524 521 518 511 449 2057 1806 1753 1750 1749 MLAT 58 8 65.2 71,7 78.1 84.4 86.4 82,0 75,3 68.3 61,3 CLAT 628 691 75.1 79.9 81,4 78.2 72.8 66.8 60.5 54.2 4250 4450 4650 4850 Ъ050 5250 5450 5650 5850 TIME IN MNSC Pig. 3. Auroral electron precipitation along the dawn- dusk meridian, observed by DMSP satellite no.7540 on Nov.29, 1984 at 0240-0301 UT. I07