Responses of the electrodynamical parameters characterizing main dynamo and loads in the magnetospheric electric circuit to variations of the governing solar wind data (SWD) are studied by the linear prediction filter method. Used parameters are approximated by the time convolution integral where a specific function of the SWD is taken as an input. Cross-polar-cap electric potential, total current, and the geomagnetic indices AE and Dst are best fitted by functions simulating electric field along a dayside neutral line in the reconnection models. Main powers (dynamo, dissipation in loads, and accumulation in the tail) are best fitted by the well-known epsilon-function. Significant differences of filters in dependence on the general level of the magnetospheric disturbancy as well as on the disturbance type are marked. Ratio of contributions of the fast and the delayed responses to a total value of the output magnetospheric parameter varies from the initial (isolated) substorm to the subsequent substorms. These results point to nonlinearity of the magnetospheric response that requires closer analysis based on the special algorithms of nonlinear filtering. Entering of the solar wind dynamic pressure along with the electrodynamical function of the SWD to input of filter increases an accuracy of approximation. Results are interpreted in terms of the energy flow inwards the magnetosphere from the dynamo spatially distributed along the open tail magnetopause. Thus, time variations of the SWD are transformed in spatial variations of inward energy flow on the scale of the magnetospheric length. It is concluded that the main magnetospheric dynamo operates as a voltage source rather than a current source. Use of two magnetospheric parameters both as an input and an output of a filter allows one to reveal some cause-effect relationships inside of the magnetosphere.

Electrodynamical processes in the polar magnetosphere are described in terms of the equivalent circuit including dynamo on the open tail magnetopause and magnetospheric-ionospheric load. Dynamo power P, electromotive forces of the dynamo and the inductance (Ed, Ei), total current I, and effective conductivity of load S are estimated using solar wind parameters, total consumption power Q, and cross-polar-cap potential U as the input data. Voltage balance in the circuit asserts in form: U = Ed + Ei. As it was anticipated, the EMF Ed responses to variations of the interplanetary electric field (IEF) Ey = - VBz with a little time delay (about 5 min) while U does it with a larger delay (about 25 min). Influence of the EMF Ei causes an ambiguous (dependent on substorm phase) U vs IEF relation looking like "hysteresis loop". At the initial phases (growth, microsubstorms) Ei weakens U while at the later phases (unloading, recovery) Ei strengthens U. That is why the high levels both of U and Q observed just at the unloading phase are supported by the internal energy source after the external source have been switched off (when IMF turns northward). Time variation of I delays relatively variation of Ed due to presence of the inductive elements in a circuit. Redistribution of current I between the magnetospheric and ionospheric loads depends on substorm time: at the initial phases a first branch dominates while at the later ones a second branch (substorm current wedge) intensifies. Both of Ed and U don't correlate with S that points to a weakness of a feedback between the dynamo and the load. Linear P vs S relation confirms this conclusion. Therefore, the results keep within a scheme where dynamo operates as a voltage source with an usual (linear) electric connection with the loads. At the same time, one can't exclude a possibility for development of the stronger (non-linear) feedback processes in the load parts of circuit (not including the dynamo).

The small-scale spatial structure of the field-aligned current (FAC) is known always present at high latitudes. Instantaneous FAC pattern occurred during substorm has constructed from ionospheric parameters obtained by means of ground-based observations. Such construction of the FAC structure by means of ionospheric data is confirmed by results of the carried out study of the connection between the time-spatial structures of the field-aligned current and the ionospheric blanketing frequency f_BEs for both positive and negative IMF B_z and B_y components during quiet and active magnetic activity: 1) a coincidence of the regions of the upward and downward FAC with the regions of enhancements and decreases of f_BEs; 2) the observed dawn-dusk asymmetry in the behavior of f_BEs with the increase of the magnetic activity; 3) the existence of the sharp latitude gradient of the f_BEs near midnight what may be connected with the narrow sheet of the upward field-aligned current in the Harang discontinuity region; 4) the opposite behavior for B_y<0 and B_y>0.

Field-aligned current pattern over the sheets of high conductivity was obtained by means of the numerical modeling with taking into account the coupling with the ionospheric layers, the magnetosphere and the ionosphere of opposite hemisphere.