Summary
Measuring the parameters of the atmospheric circuit with hourly and daily time resolution is difficult to achieve and demonstrate. However, a relationship between Vi, the ionosphere- to-ground potential difference, and Ez, the near-ground-level vertical electric field, has been demonstrated for measurements at the Antarctic plateau site at Vostok (78.5S, 107E; 83.6S mag.). In polar regions, the solar wind (external generator) imposes an additional variation on the globally-uniform meteorological contribution (internal generator) to Vi. Empirical models derived from co-incident satellite measurements of the solar wind and polar cap ionospheric electric fields provide an independent estimate of the external generator. Vostok Ez responds to variations in the modeled solar-wind-imposed potential difference across all hours and all seasons. A delay of 23 minutes is measured between the solar wind at the magnetopause and the ionosphere over Vostok, for the best response in Ez. A sun-weather association between ground-level pressure at high-magnetic-latitude sites and the interplanetary magnetic field is likely linked via the current, Jz, in the atmospheric circuit. A larger pressure response at Antarctic plateau sites is associated with variations in the daily- averaged Vostok electric field measurements. The `sensitivities' (hP per kV) of these variations are similar. This supports both hypotheses: that the sun-weather process operates via the atmospheric circuit, and that day-to-day variations in the global component of Vi map into the ground-level electric field measurements made on the Antarctic Plateau. Additionally, Antarctic coastal and Arctic ground-level pressure responds with near-zero lag with respect to solar-wind-corrected, day-to-day variations in Antarctic Vostok Ez. The close temporal alignment of responses at the Arctic and Antarctic sea-level-sites suggests that the global signal in the Antarctic plateau electric field variations is the signature of the longstanding theoretical concept of a global atmospheric circuit, which provides a nearly-globally-uniform ionosphere-surface potential difference at any given time. Multi-regression analysis of variations in local meteorological condition, the solar-wind-imposed contribution to Vi and Vostok Ez supports the measurement of atmospheric circuit influences during `fair-weather' conditions. Some coincident measurements of Ez at Dome C (Concordia: 75.0S, 123E; 88.8S mag) and Vostok are also presented, demonstrating a broad similarity of response.