Abstract:
The scope of this paper is to explore the mechanisms operating over Maitri (70.76°S, 11.74°E,
117m above mean sea level), a coastal Antarctic station, that produce an anomalous fair-weather diurnal
pattern of the atmospheric electric potential gradient (PG) and air-Earth current density (AEC). The anomaly in
the diurnal variations of AEC and the PG is displaying an ostensible minimum at ~10 UT and a diminished
response to the thunderstorm over the African continent in the 14–16 UT time frame. The data sets
(2005–2014, except 2012) of the PG, and to some extent, AEC, from Maitri, are used to explore this anomaly. It
follows that the fair-weather electrical phenomena over Maitri can be ascribed to global electrified
convection on the one hand and to regional phenomena like convection due to the replacement of warm air
by katabatic winds on the other hand. The katabatic winds originate on the polar plateau and blow from
~130° at Maitri which are likely to transport various elements from the mountain slopes, and space charge
from the polar plateau is expected to produce various disturbances in the PG and AEC monitored over the
coastal Antarctica. This mechanism may be responsible for peaks in the early UT hours and also for the
anomalous behavior of atmospheric electrical parameters observed at Maitri. Maitri data are compared with
that of Carnegie cruise and Vostok to explain the source of anomaly.
