Summary
The atmospheric electric field Ez measured at the Antarctic Plateau station of Vostok made it possible to estimate the role of the main generators in formation the global electric circuit. In the polar region during the periods with good weather conditions the classical diurnal curve (Carnegie curve) is strongly influenced by the ionospheric potential variations. Careful statistical analysis of single-site electric field data has provided experimental proof that this solar wind generator can be measured at ground level. Lightning is part of an atmospheric electric circuit of global extent. The field Ez behavior at Vostok station was compared with a number of lightning strokes obtained from data of the ground-based network of electromagnetic measurements. It has been found out that the average hourly values of Ez evidently negatively correlate with the number of intense lightning strokes. The calculations based on the nonstationary model indicate that the contribution of the electric field caused by intense cloud-to-ground lightning discharges to maintaining the global electric circuit is not more than 1% of the total observed gradient of the electric field potential, and only the quasistationary model can apparently explain the generation of the experimentally observed electric field.