[1] Interyear consistency is demonstrated in the bi-monthly average diurnal vertical electric field measured over $720 ''fair-weather'' days collected during a 5-year interval (1998 to 2002) at Vostok (78.5°S, 107°E; magnetic latitude 83.6°S), Antarctica. After correcting for the influence of polar-cap convection, seasonal peaks in the average electric field values occur around July-August with a diurnal maximum at $ 2050 UT while lowest average magnitudes are measured near November-December when the associated diurnal maximum occurs at $1830 UT. These variations are consistent with expected seasonal changes in global thunderstorm activity. Comparisons of ground-level vertical electric field measurements (Vm À1 ) with Weimer-1996 model cross-polar cap potentials above Vostok (kV) for individual UT hours yield significant correlations over all hours but with reduced standard errors around local magnetic noon ($1300 UT). This implies a more direct linkage between solar wind parameters and the cross-polar cap potential near magnetic noon, for this site (magnetic latitude: 83.6°S). An all hours-all seasons linkage factor of 0.76 ± 0.06 Vm À1 per kV is determined, broadly consistent with an average ionosphere-ground potential difference of $250 kV and a measured average vertical electric field of 185 Vm À1 . Evidence is presented supporting a seasonal variation in this linkage factor, with generally lower magnitudes in the austral winter (May to August).Citation: Burns, G. B., A. V. Frank-Kamenetsky, O. A. Troshichev, E. A. Bering, and B. D. Reddell (2005), Interannual consistency of bi-monthly differences in diurnal variations of the ground-level, vertical electric field,

Temperature observations between 20 and 120 km from the SABER instrument on the TIMED spacecraft are used to investigate the nature of planetary wave activity during the 60 days prior to the midwinter stratospheric warming that commenced on 26 September, 2002 in the Southern Hemisphere. The primary wave components consist of eastward‐propagating quasi‐10‐day waves with zonal wave numbers s = 1 and s = 2, and a stationary planetary wave with s = 1. The waves are found to extend from the lower stratosphere to the 100–120 km height region with surprisingly little amplitude attenuation, although wave amplitudes oscillate with altitude like a standing wave pattern. Time evolution of the waves is also addressed with emphasis on 86 km altitude, where temperature observations from three Antarctic stations at Davis (69°S, 78°W), Rothera (68°S, 68°W) and Syowa (69°S, 40°E) are available during the same period. We demonstrate that the temporal evolution of temperature obtained by superposition of the waves derived from SABER measurements accounts for nearly all the temperature variability observed at the longitudes of the three Antarctic stations.

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