The relationship between variations of the atmospheric electric field in the southern polar region and thunderstorm activity

Observations of the atmospheric, near-surface vertical electric field component E-z have been carried out at the Russian-Antarctic station, Vostok, since 1998 under the framework of a cooperative Russian-Australian project. Only data satisfying "fair weather" conditions are selected for the subsequent analyses. Behavior of E-z field at Vostok station is compared with thunderstorm occurrence determined from a network of ELF magnetic field measurements in April 1998 and with simultaneous VLF emission measurements at Halley Bay (Antarctica). We find no correlation between the 5 min averages of E-z and the lightning flashes intensity or between E-z and VLF emissions, although significant correlation between E-z and VLF emissions is observed in particular cases. The same statistical results have been obtained from a comparison of hourly averaged values. Moreover, even the mean diurnal variation of electric field derived for 10 fine weather days in April 1998 turned out to be inconsistent with the mean diurnal variation of the lightning flashes for the same days. Reasons of these inconsistencies are discussed.