No abstract available

[en] It is shown, that there is critical value of Dange potential (φ_D⁰) where comprehensive quasistagnant region occurs in magnetosphere boundary layer, under combined action of Dange (φ_D) and Exford-Heins (φ_E) convection. Convection under φ_D<φ_D⁰ in this layer occurs in antisolar direction, under φ_D>φ_D⁰ - is directed to the Sun

No abstract available

No abstract available

[en] Complete text of publication follows. Space-based geomagnetic observations are usually made on board low altitude near polar orbiting satellites. These satellites sweep all longitude sectors and provide quasi regular and homogenous global scale dataset. Especially, for the study of the equatorial electrojet (EEJ) features including its longitude dependence, only satellite magnetic measurements are capable of providing such global coverage. However, the orbit along-track methods of extracting the EEJ signature from satellite observations do not allow an accurate estimate of its peak current density in certain longitude sectors. By comparing ground-based and satellite observations, we show that satellite orbit along-track methods fit well the latitude profiles of the EEJ magnetic effect when the satellite paths are perpendicular to the dip-equator, as in most part of the longitude sectors of Asia and Africa. Otherwise, the EEJ latitude profiles are biased, which leads to poor estimate of the EEJ features (magnetic signature, peak-current density, position of the EEJ center, etc.), as in the Atlantic Ocean and most of South American sectors, where the dip-equator is strongly tilted from the East-West direction.

[en] A simple-minded 'model' is used in order to visualize the gross features of polar cap electric fields, in particular the 'diode' effect which had emerged already from earlier observations and the asymmetry between the electric fields observed on the dawn and dusk sides of the polar cap, which depends on Bsub(y)

[en] The viable theories already proposed to explain polar ozone holes generally fall into two main categories, namely, chemical theories and dynamical theories. In both of these categories, polar stratospheric clouds (PSCs) are taken as part of the essential basis. Besides, all the dynamical theories are based upon temperature changes. Since formation of the PSCs is highly temperature-dependent, it has been concluded from recent research (e.g. see Kawahira and Hirooka) that temperature changes are a cause, not a result of ozone depletion in polar regions. On this basis, formulations are developed that represent short-term and long-term temperature variations in the polar regions due to natural processes. These variations, which are confined to a limited area around each pole, include specific oscillations with periods ranging from ∼ 2 years up to ∼ 218,597 years. Polar ozone variations are normally expected to be influenced by these temperature oscillations. It is, therefore, apparent that the generally decreasing trend observed in mean October ozone column at Halley Bay (76 deg. S, 27 deg. W) from 1956 up to 1987 is mostly caused by the decreasing phase of a combination of two natural temperature oscillations, one with a period of ∼ 70-80 years and the other with a period of ∼ 160-180 years. Contributions of other natural temperature oscillations are also mentioned and briefly discussed. (author). 35 refs, 4 figs

[en] Results are presented of test calculations by means of the method of diagnostics of the integral parameters of an electric equivalent RL network of the polar magnetosphere. Results are agreed with the circuit where the primary generator-dynamo is a voltage source, having ordinary (linear) contact with a magnetospherical-ionospherical loading. 10 refs., 1 fig., 4 tabs

[en] Short note

[en] During the International Magnetospheric Study period our understanding of phenomena in the polar ionosphere and the role of this region in the coupling between the ionopshere and the magnetosphere has progressed to a point where many self-consistent pictures are emerging. In many cases the required relationships between electric currents, conductivity, and electric field can be demonstrated, and observed phenomena can be explained in terms of realistic variations in these parameters. The distribution and composition of plasma can be reconciled with realistic patterns of large-scale plasma motion and ion production regions. The extent of our understanding is reviewed here. There are, however, gaps in our understanding of the electrodynamic and the plasma properties of the polar ionosphere. But the gaps show promise of being filled by our ability to properly formulate the problems and to provide the necessary measurements from present and future spacecraft missions