Summary
Apparent drift motion of polar cap arcs may be indicative of plasma convection processes in the ionospheric plasma. The dynamics of a number of individual polar cap events observed by a dual wavelength all-sky imager at Scott Base have been analysed in detail. The imager, which records optical emissions at 630nm and 428.7nm has been operated at Scott Base, (79.96°S, 327.61°E magnetic), during the winters of 1996 to 1998. The events presented have been selected to show representative examples of arcs observed primarily in the dayside. Of interest is the speed and direction of the polar cap arc drift motion with respect to solar wind and interplanetary magnetic field conditions. Events were observed between 10:00 and 19:00 local time (mid-morning to dusk), where drift velocities varied between 60 m s-1 away from the invariant pole and 1000 m s-1 polewards. Another example shows a drift velocity of 300 m s-1 perpendicular to the pole direction. Each of the examples show different velocities and drift direction, for differing solar wind condition, at different times. The small number of images in the initial data set needs to be expanded into a three year data set, and include data from other instruments, in order to fully understand the correlations of polar cap arc drifts with solar wind/interplanetary magnetic field (IMF) conditions.