  Simultaneous measurements of the small-, intermediate- and large- positive
ions and air earth current density made at a coastal station, Maitri at
Antarctica during January to February 2005, are reported. Although, small and
large positive ion concentrations do not show any systematic diurnal
variations, variations in them are almost similar to each other. On the other
hand, variations in intermediate positive ion concentrations are independent of
variations in the small/large positive ions and exhibit a diurnal variation
which is similar to that in atmospheric temperature on fair weather days with a
maximum during the day and minimum during the night hours. No such diurnal
variation in intermediate positive ion concentration is observed on cloudy days
when variations in them are also similar to those insmall/large positive ion
concentrations. Magnitude of diurnal variation in intermediate positive ion
concentration on fair weather days increases with the lowering of atmospheric
temperature in this season. Scavenging of ions by snowfall and trapping of Alha
- rays from the ground radioactivity by a thin layer of snow on ground, is
demonstrated from observations. Variations in intermediate positive ion
concentration are explained on the basis of the formation of new particles by
the photolytic nucleation process.
