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.

MERIDIONAL CURRENT CIRCULATION WITHIN THE IONOSPHERE ON THE DUSK SIDE. The latitudinal profile of ДD or AY (observed minus calculated reference model field value for D- or Y-component of the geomagnetic field) has revealed a systematic deviation on the dusk side, i.<>. negative (westward) in the north and positive (eastward) in the south of thrf magnetic dip equator. These devi ations are the greatest at the dip latitude of 8°N and 8°S with their magnit ude of 10-20 nT depending on the longitude of the observation area over the world. This systematic deviation of ДD or A Y is observed for every path of the.MAGSAT flight on the dusk side, almost uninfluenced by the geomagnetic activity, but not at all on the morning side. The morphological features of this phenomena are shown in detail in the papers by Maeda et al.(1982,1985) and by Kane and Trivedi (1985). Maeda et a l .(1982,1985) attributed this й D or A Y deviation to a toroidal magnetic field within the ionosphere, which is produced by an electric current circulation in the vertical cross-section of the ionosphere within the merid ional plane. As shown in Pig.5, the observed systematic D-component deviations are attributable to a meridional current circulation near the dip equator within the ionospherej such a meridional ourrent has been proposed by Untiedt (1967) and Sugiura and Poros (1969) in a two-dimensional treatment for the noon condition, and detected experimentally by Musmann and Seiler (1978) from their rocket observation. Takeda and Maeda (1983) showed a theoretical possib ility for the existence of an upward electric current above the dip equator and its return current within a meridional plane on the dusk side. GLOBAL ANTISUNWARD CURRENT IN THE MAGNETOSPHERE-IONOSPHERE DURING MAGNETIC STORMS. MAGSAT Analysis discovered a net electric current flow of a few million Amperes in an antisunward direction below the satellite level during magnetic storms, but such a current is almost absent on quiet days (Suzuki and Fukushima,1984; Suzuki et al.,1985). As schematically shown in Pig.6, MAGSAT can be thought to be a small probe in a vast plasma space around the earth, and it provides us with the sector magnetic field data, 16 times a second, along a circular orbit perpendicular to the sun-earth direction. A direct application of Ampere's theorem enables us to calculate the total amount of net electric current across the plane enclosed by the MAGSAT orbit, through a line-integration of the magn etic field component tangential to the satellite orbit. It must be borne in mind that Ampere's hold only for a stationary state (or the magnetic field can be measured simultaneously everywhere along the integration circuit), so that it is necessary to avoid a spurious effect arising from the earth's rotat ion under MAGSAT during its revolution. The authors regret that the undesir able spurious effect remained unelim inated in an earlier paper (Suzuki Pig. 6. Application of Ampere's theorem needs a correlation for the earth's rotation, because of a spurious effect coming from the time variation of My, the component of geo magnetic moment on the plane of MAGSAT orbit. 81