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.

The times of the beginning of the maximum value and the end of the disturbance agree very well with AU and AL. This manifests itself by high correlation coefficient (number in the right side corner). This rather synchronous devel opment of AL and AU ought to be attributed to a development of the convection process. The AL data, however, have to some extent a typical substorm devel opment (3 November 1967, 26 January 1968). In these cases, driving process and unloading process would simultaneously reach their maximum. Here, we must assume that the convection increases during the substorm explosion. On the other hand, the examples on the right side of Fig.2 show a distinctly separate development of eastward and westward electrojet. The eastward electro jet often grows before the beginning of intensification of the westward elec trojet and the maxima are reached at different times with AU and AL. May the eastward electrojet, generally occur with less intensity than the westward electrojet, it ia quite possible that the intensity in the eastward electro jet is greater than in the westward electrojet. This is to be seen in Pig.2 for 1 June 1970, 28 May 1972 and 28 May 1970. This weak relationship between AL and AU development for many cases manifests itself by a low correlation coefficient (number in the right side corner). Considering this often not synchronous development between AL and AU, it must be asked why the intensity of the eastward electrojet is often greater than that of the westward one. Why is the eastward electrojet often intensified only then when the intensity of the westward electrojet is greatly decreasing (25 May 1967, 28 February 1968, 28 May 1970, 15 May 1972)? For some cases of the left side of Fig.2 according to the outlined idea it must be supposed that the convection increa ses during the substorm, and for some cases of the right side, that it decrea ses during the substorm (26 May 1966, 25 May 1967 last substorm, 15 May 1972). If the convection conception of the eastward electrojet is stlcked to be the only cause, a rather irregular development of both convection electrojets must be expected, at which it is not quite reasonable that with an increasing of the convection electric field the eastward electrojet is increasing and the westward electrojet is decreasing and vice versa. The behaviour of AL and AU is also interesting on 28 February 1968 in Fig.2. Here, the westward electrojet is developing earlier than the eastward electrojet. Thereby, the AL development is typical for a substorm electrojet. In this example we must ask for the driving process (accumulation phase) before the unloading process. In Fig.3, on the left side the AU and AL data of such disturbances are compiled where the intensity of the eastward electrojet with westward electro jet existing is small or oven zero. On the right side of these figures there are examples with extremely intense westward electrojet. Here, too, the hetero- genity of the development of the eastward electrojet is to be seen. In many сааез the eastward electrojet is rather weak (14 December 1966, 31 December 1967, 11 February 1969). Sometimes, however, the eastward electrojet can be the dominating phenomenon (11 January 1971). Afonina and Feldstein (1971) also speak of a non-simultaneous development of AU and AL during disturbed conditions. A very instructive example from 1982 is shown in Fig. 4 where the hourly means of AU and AL indices of July 13/14, 1982 are represented. The picture of the AU disturbances in appearance and intensity scarcely differs from that of the AL disturbances with substorm character. Thus it becomes clear that the consideration of a lot of individual effects supplies a very manifold and partly confused picture. 60