Simultaneous observations of atmospheric vertical potential gradient from coastal Antarctic stations Bharati and Maitri

Abstract

Simultaneous observations of the atmospheric electric potential gradient (PG) at Bharati and Maitri stations were studied from 2014 to 2016. A new regional diurnal pattern of fair-weather PG for the coastal Antarctic region, perhaps the ubiquitous characteristics of the PG for the coastal Antarctic region, has been identified. This pattern has a significant broad minimum around noon hours. It is around this time the wind speed is also maximum. The PG data of past years of Syowa, Vostok, and Carnegie Cruise were also used in this study. The surface wind distorts the fair-weather diurnal pattern of PG over Bharati more intensely than at Maitri. The katabatic wind effect on the PG at Bharati appears to be more intense than at Maitri. The topography and katabatic winds associated with the Lambert glacier could be the reason. The observation of Bipolar Air Ion Concentration (BAIC) suggests that the wind speed significantly affects the concentration by accumulation and dispersion. The concentration is maximum when the wind speed is minimum. As the air ion concentration controls the conductivity, the PG is expected to be minimum during these hours to produce an anomalous diurnal pattern in the PG at Bharati. Data quality is improved by measuring the PG with a field monitor at the surface level instead of at an elevated position. This study provides new hope in pursuing globally representative data of the PG for further investigations on the global thunderstorm activity and the solar-terrestrial weather relationship.